School of Physics & Astronomy

Find a PhD Project Here

Opportunities for fully funded PhD or EngDoc research projects are available in all fields of research within the School. You may search for current projects on this page. APPLY HERE for a PhD Place.

 PhD in Photonics
 PhD in Condensed Matter
 PhD in Astrophysics

Search current PhD opportunities in the School of Physics & Astronomy:-




Condensed Matter

Atomic-scale imaging of magnetism and superconductivity in iron pnictides
Wahl, Dr Peter - gpw2@st-andrews.ac.uk

In many unconventional superconductors, magnetism and superconductivity occur in close proximity to each other - which is surprising given that they are usually considered mutually exclusive properties of a material. This is also true for the iron pnictide superconductors, where in several materials magnetism and superconductivity appear to coexist from macroscopic measurements. In this project, you will take an atomic scale view at the magnetic order and the properties of the superconducting properties using low temperature spin-polarized scanning tunneling microscopy[1]. Combining images of the magnetic order with a characterization of superconductivity from tunneling spectroscopy will allow to establish whether magnetism and superconductivity coexist microscopically, or whether they are really competing. These results provide important benchmarks for theory, and may help to improve our understanding of superconductivity in these materials.

You will be using bespoke low temperature scanning tunneling microscopes, which are installed in a new ultra-low-vibration facility at the University of St Andrews.

[1] Enayat et al., Science 345, 653 (2014).
Local control and manipulation of electronic properties of transition metal oxide surfaces
Wahl, Dr Peter - gpw2@st-andrews.ac.uk

Transition metal oxides host a wide range of physical properties and functionalities, making them an ideal platform for implementing potential future devices. The aim of this project is to establish novel ways to manipulate the local properties of transition metal oxides by using a scanning tunneling microscope to enable writing device structures at the atomic scale into the surface of the material. To establish the properties of these written device structure, you will first use scanning tunneling spectroscopy, but later also explore possibilities to contact the written structures macroscopically to study transport through these and enable actual device operation.
While initial studies will be performed on bulk material, it is envisioned that at later stages of the project, thin-film samples grown by reactive oxide molecular beam epitaxy will be used.
Quantum Critical Points in Ferroelectrics
Scott, Prof Jim - jfs4@st-andrews.ac.uk

When crystals undergo phase transitions at or near zero degrees Kelvin their dynamics differ from those at higher temperatures. Entropy is still involved but arises from quantum mechanical uncertainty, rather than classical effects; this mixes together spatial and temporal fluctuations. Most systems studied thus far involve ferromagnetism or superconductivity, but some work [1,2] has been done by Scott on ferroelectrics. In a pseudo-cubic structure such as SrTiO3 or KTaO3 the main effect is that the isothermal electric susceptibility (dielectric constant) varies as 1/T-squared, rather than the classic Curie-Weiss 1/T, and the effective dimensionality is d+1 = 4. But in highly uniaxial materials, the effective dimensionality is d+1 = 5, which results in the dielectric constant varying exactly as 1/T-cubed [3].

We have recently demonstrated that in the uniaxial materials BaFe12O19, SrFe12O19, and PbFe(12-x)Ga(x)O3. The Ba-isomorph is the most profitable magnetic material in Nature, with £2 billion in sales every year (a few grams for every person on Earth!), primarily as the magnetic stripe material for credit cards. Therefore, although this project is unapplied, it is related to device materials of great commercial interest.

[1] S. E. Rowley et al., Nature Physics (2014)
[2] S. E. Rowley et al., arXiv condmat (2014)
[3] D. Khmelnitskii, JETP Lett. (2014)

The thesis work will not involve growing crystals (they are already in hand) nor building a lab; most of the kit is already operational in Dr. F. Morrison's lab in the School of Chemistry. However, a relatively sophisticated level of data analysis and modelling will be encouraged. Therefore although the project is experimental, students with a high level of interest in theory might find it attractive.

It is probable that summer salary would be available for a PhD student wishing to begin in June or July.
Real space imaging of complex magnetic phases and quantum critical matter
Wahl, Dr Peter - gpw2@st-andrews.ac.uk

Quantum materials often exhibit intricate magnetic orders, and small changes of a tuning parameter such as doping or magnetic field can lead to rather dramatic changes in the macroscopic properties and the magnetic order of the materials. In this project, you will use spin-polarized low-temperature scanning tunneling microscopy and spectroscopy to characterize magnetic order in quantum materials in real space.
This work will build on initial studies by the group which have demonstrated imaging of magnetic order in quantum materials [1,2]. Applying this technique to metamagnetic materials will enable to characterize how magnetic order emerges at a quantum critical point, and what the influence of disorder is. Further it will provide atomic-scale information about the interplay between competing orders, such as magnetic order and charge order and the electronic structure.

You will be using bespoke low temperature scanning tunneling microscopes, which are installed in a new ultra-low-vibration facility at the University of St Andrews.

[1] Enayat et al., Science 345, 653 (2014).
[2] Singh et al., Phys. Rev. B 91, 161111 (2015).
Room-temperature Multiferroics
Scott, Prof Jim - jfs4@st-andrews.ac.uk

Multiferroics are usually defined as crystals that are simultaneously ferromagnetic and ferroelectric. Most are also magnetoelectric, meaning that their magnetization M can be switched by applied electric field and their polarization P switched via applied magnetic field H.

This PhD thesis project will emphasize the materials GaFeO3 and its isomorphs, as well as PbFe(1/2)Nb(1/2)O3 and related Ta, Ti, and Nb compounds.

The thesis work will not involve growing crystals (they are already in hand) nor building a lab; most of the kit is already operational in Dr. F. Morrison's lab in the School of Chemistry. However, a rewlatively sophisticated level of data analysis and modelling will be encouraged. Therefore although the project is experimental, students with a high level of interest in theory might find it attractive.

It is probable that summer salary would be available for a PhD student wishing to begin in June or July.
Superconductivity in Non-Centrosymmetric Materials and Structures
Wahl, Dr Peter - gpw2@st-andrews.ac.uk

The aim of this project is to investigate experimentally the influence of broken inversion symmetry on superconductivity in a variety of non-centrosymmetric (NCS) materials.
Most crystalline metals have a structure that maps onto itself exactly under inversion of spatial coordinates. Such materials are termed “centrosymmetric” and when they become superconducting, the spatial part of the Cooper pair wavefunction must have a definite parity, i.e. inversion simply multiplies it by ±1. This imposes restrictions also on the spin configuration within the Cooper pair. By contrast, in non-centrosymmetric superconductors where the crystal structure breaks inversion symmetry, such restrictions do not apply. Amongst the properties predicted for non-centrosymmetric superconductors are mixed spin-singlet/spin-triplet pairing, enhanced critical fields and spatially modulated superconducting states. Whilst unusual superconducting properties have been detected in a number of NCS materials, there is relatively little firm experimental evidence linking these to the lack of inversion symmetry; for example only in very few cases has a substantial triplet component of the order parameter been firmly established.
The project will be focused on NCS superconductors where the electronic correlations are weak, since these offer the chance to isolate the role of the broken inversion symmetry. The experiments will focus on using low temperature scanning tunneling microscopy and spectroscopy to establish the structure of the superconducting order parameter and study the influence of defects of different dimensionalities on the superconducting properties.
2D Quantum Materials
King, Dr Phil - pdk6@st-andrews.ac.uk

As part of a generously-funded research project from the Leverhulme Trust, we are seeking ambitious and motivated PhD students to join a major research initiative aimed at investigating the electronic structure and collective states of two-dimensional quantum materials. The remarkable electronic, optical, and structural properties of graphene, a single atom-thick layer of carbon, has spurred enormous interest in 2D materials. In this project, you will seek to develop 2D materials, and their combinations, which incorporate the effects of pronounced electronic interactions, focusing on transition-metal dichalcogenide (TMD) compounds. Bulk TMDs are known to support a wide variety of striking physical properties such as superconductivity and charge density-wave states, but how these are modified when the material is restricted to just a single layer in thickness are only just starting to be explored, and combining strongly-interacting 2D materials in different configurations and environments promises a huge array of exciting possibilities to stabilise rich phase diagrams and unique properties. The work undertaken will build on the group’s existing activity in the study of TMDs, strong spin-orbit, topological, and interacting electron systems [1-6], and ultimately aims to develop new routes towards the “on-demand” control of the quantum many-body system underpinning the physical properties of 2D quantum materials. Projects are available developing the growth of single monolayers and heterostructures of TMD compounds using a recently-installed state-of-the art molecular-beam epitaxy system in St Andrews and utilizing a linked system for angle-resolved photoemission spectroscopy, as well as further ARPES and spin-resolved ARPES work at international synchrotrons, to probe the resulting electronic structure and many-body interactions of the materials synthesized. There are also possibilities to spend extended research visits with our collaborators in Tokyo and in Italy. As part of this project, you will undertake experiments at national and international facilities. Thus, a willingness to travel is an essential prerequisite. For further information, or to discuss specific research possibilities, please contact philip.king@st-andrews.ac.uk.

[1] King et al., Nature Comm. 5 (2014) 3414
[2] King et al., Nature Nano. 9 (2014) 443
[3] Riley et al., Nature Physics 10 (2014) 835
[4] Riley et al., Nature Nano. 10 (2015) 1043
[5] King et al., PRL 107 (2011) 096802
[6] Bawden et al., Science Advances 1 (2015) 1500495
Ambient pressure photoemission spectroscopy of organic semiconductor devices
Turnbull, Prof Graham - gat@st-andrews.ac.uk

Ambient pressure photoemission spectroscopy is a new technique to measure the energy levels of materials. Combined with scanning Kelvin probe spectroscopy APS can provide information about the electronic properties of thin film materials relevant to LEDs, solar cells, sensors and lasers. The aim of this project will be to combine measurements of the energy levels of organic semiconductors to understand their operation in optoelectronic devices.

The HOMO and LUMO levels of organic semiconductors are crucial to charge injection, exciton formation, energy transfer and charge transfer in OLEDs, solar cells, lasers and chemical sensors. Currently the standard measurement to determine energy levels is cyclic voltammetry but this is typically used to measure individual molecules in solution, and there would be a lot of advantage if we could measure directly the materials int he solid-state including thin films as used in devices.

Applications of these measurements would be to better understand the operation of solar cells, OLEDs and thin film chemical sensors.
Artificial quantum materials
King, Dr Phil - pdk6@st-andrews.ac.uk
Wahl, Dr Peter - gpw2@st-andrews.ac.uk

The epitaxial compatibility of many oxides which, in bulk form, host an extraordinarily wide array of physical properties opens almost limitless possibilities for creating new artificial materials structured at the atomic scale [1]. Recent advances in atomically-precise deposition techniques have opened new potential to manipulate the properties of these ubiquitous but still poorly-understood materials [2], creating new "designer" compounds with tailored properties not found in bulk. You will exploit a brand new £1.8M growth facility to build up transition-metal oxide materials one atomic layer at a time, exploiting tuning parameters such as epitaxial strain and the layering of disparate compounds to selectively tune their functional properties. To provide direct feedback on how this influences the underlying quantum states in these complex materials, you will employ advanced spectroscopic probes such as angle-resolved photoemission [3] or scanning tunneling microscopy and spectroscopy [4], utilizing our state-of-the-art capabilities in St Andrews. Together, this promises new insight into the rational design of quantum materials and their potential for future quantum technologies.

[1] J. Mannhart and D. Schlom, Science 327, 1607 (2010).
[2] P.D.C. King et al., Nature Nano. 9, 443 (2014).
[3] J.M. Riley et al., Nature Phys. 10, 835 (2014).
[4] M. Enayat et al., Science 345, 653 (2014).
Collective excitations of correlated and spin-orbit coupled quantum materials
King, Dr Phil - pdk6@st-andrews.ac.uk

A key goal of condensed matter physics is to develop a thorough understanding of the microscopic properties of materials to enable the rational design of new compounds with desired characteristics. A major challenge, however, is that their particles often do not act independently, but collectively. This collective behavior can have striking consequences, such as superconductivity and magnetism, but can be challenging to probe experimentally and understand theoretically. In this project, you will initially develop a state-of-the-art instrument to probe the inelastic scattering of low-energy electrons, opening exciting new opportunities for studying the collective excitations in materials with unprecedented resolution. You will apply this to investigate exotic metals known to exist at the surface of a special type of insulator called a topological insulator [1] as well as correlated quantum states in designer quantum materials [2]. This will provide new insights on their collective excitation spectra and many-body interactions, key to understanding their physical properties.

[1] King et al., Phys. Rev. Lett. 107 (2011) 096802
[2] King et al., Nature Nano. 9 (2014) 443
Controlling emergent quantum phases through strain-tuning of electronic structure
Hicks , Dr Clifford - cwh10@st-andrews.ac.uk
King, Dr Phil - pdk6@st-andrews.ac.uk
Mackenzie, Prof Andy - apm9@st-andrews.ac.uk

The strong interactions at the heart of correlated electron materials yield striking collective states such as superconductivity or magnetism, and often mediate giant responses to small external perturbations. This offers unique opportunities to tune these subtle quantum many-body systems, to shed new light on their underlying physics and ultimately to engineer desired functional properties. In this project, you will exploit externally-applied and continuously-tunable mechanical strain in an attempt to harness control over emergent phases in correlated solids, for example tuning unconventional superconductivity in Sr2RuO4 and controlling quantum criticality in Sr3Ru2O7. You will perform low-temperature transport measurements as a function of uni- and bi-axial strain using custom apparatus within the world-leading facilities of the Max-Planck Institute for the Chemical Physics of Solids in Dresden, Germany. You will also design similar apparatus that can be integrated within our state-of-the-art system for angle-resolved photoemission (ARPES) in St Andrews, as well as in ARPES systems at synchrotron light sources within the UK, Europe and the USA. This will allow you to track the corresponding electronic structure changes that control the materials’ transport and thermodynamic properties with unprecedented detail. This project is offered as part of a Max Planck – CM-DTC initiative (http://cm-dtc.supa.ac.uk/research/max%20planck.php). You will spend part of your time performing research in MPI Dresden (with Dr. Hicks & Prof. Mackenzie), part in St Andrews (with Dr. King), and will also undertake experiments at national and international facilities. Thus, a willingness to travel is an essential prerequisite. Collaborations in this area are also envisaged with the STM group of Dr. Peter Wahl in St Andrews.
Decoherence of quantum registers
Lovett, Dr Brendon - bwl4@st-andrews.ac.uk

Quantum computing has undergone something of a revolution in recent years. From being a technology that only a few thought might be ever be realized, a small scale computing device is now a realistic target in the next five years.


This has been driven by remarkable recent progress in both theory and experiment. In particular, it is now established that the coherence time of single qubits in solid state systems is many orders of magnitude longer than that required to execute a simple logic gate.


The timing is now perfect to develop a detailed blueprint for how to scale up from one to many qubits. In particular, we must gain a detailed understanding of how to describe a system of several coupled qubits interacting with a common environment. In this situation, many of the more straightforward approximate approaches to modelling open quantum systems fail. You will therefore exploit more sophisticated, and accurate, methods, such as those based on Feynman’s path integral formulation of quantum mechanics, to make predictions about the dynamics of quantum registers.


Emergent Order in Hybrid Photon-Atom Systems
Braunecker, Dr Bernd - bhb@st-andrews.ac.uk

Novel self-ordered phases can emerge in a conductor with interacting electrons and embedded magnetic moments [1,2]. This is quite surprising because the energy and time scales of the considered magnetic moments (e.g., nuclear spins) differ by orders of magnitude from those of electrons. Yet, within this decoupling of scales, the ordering mechanism is general and not bound to specific materials. Quite remarkably such self-ordered phases have made recently a strong link with the currently much discussed physics of topological superconductors and Majorana bound states [3].

In this PhD project, we shall explore systems in which the time and energy scales are turned upside down, notably, in which the effective interaction that triggers the order travels at a turtle's pace. This is an extreme limit in which this slow dynamics will play a further important role. For a definite example we will focus on cavity photons that are coupled through an interacting atomic gas, which is of the type of systems that are under investigation, for instance, in the group of Prof Jon Simon at the University of Chicago (http://simonlab.uchicago.edu).

[1] B. Braunecker, P. Simon, and D. Loss, Phys. Rev. Lett. 102, 116403 (2009) [arXiv:0808.1685].
[2] B. Braunecker, P. Simon, and D. Loss, Phys. Rev. B 80, 165119 (2009) [arXiv:0908.0904].
[3] B. Braunecker and P. Simon, Phys. Rev. Lett. 111, 147202 (2013) [arXiv:1307.2431].
Energy Transfer Networks
Lovett, Dr Brendon - bwl4@st-andrews.ac.uk

Recent experiments on photosynthetic complexes reveal the possible presence of quantum coherence between excitations on different parts of the protein complexes involved. It has been conjectured that these quantum correlations may lead to enhanced energy transfer, and thus to more efficient solar cells.

In this project, you will explore the interplay of quantum and classical mechanisms for moving electronic energy around networks of molecules. On the one hand, quantum correlations can lead to constructive interference between different parts of the network, leading to a faster transport of energy. On the other hand, such correlations may lead to destructive interference, and cause excitations to get stuck. Classical hopping may relieve this problem. You will predict the optimal balance of classical and quantum processes that lead to the highest rate of energy extraction from the network. You may need to explore the role of length scale, network topology, and use thermodynamic concepts to address this problem.

The project will be in collaboration with theorists at the University of Oxford, and may be tested in the laboratories of collaborators both in St Andrews, and at the Universities of Oxford and Cambridge.
Exciton Diffusion in Organic Semiconductors
Samuel, Prof Ifor - idws@st-andrews.ac.uk

The discovery of semiconducting properties in organic materials has opened major new directions in semiconductor physics. Organic semiconductors combine the simple fabrication and tuning of properties that is typical of plastics with novel optoelectronic properties useful for devices such as light-emitting diodes and solar cells. The low-dimensional nature of these materials means that excitons (electron-hole pairs) are strongly bound even at room temperature and play a very important role in their physics. Whilst charge transport has been widely studied, exciton transport has been largely overlooked. We have now developed techniques based on time-resolved spectroscopy that allow the measurement of exciton diffusion. We now wish to apply them to understand the physics of exciton diffusion and the factors controlling it. A breakthrough in this field could in turn lead to a breakthrough in the efficiency of organic solar cells.
Experimental and Theoretical Investigation of Spatially Modulated Magnetic Phases Near to Quantum Criticality
Huxley, Prof Andrew - ah311@st-andrews.ac.uk

The possibility of magnetic spin-crystals formed by the superposition of helical spin modulations with different wave-vectors has been a subject of much recent experimental and theoretical work. Signatures of phases with this property have been found in an array of materials including MnSi and Sr3Ru2O7. On the theoretical side, there are several ways in which such states might form. These include the formation of spiral modulation due to a Dzyalosinskii-Moriya spin-orbit interaction in itinerant magnets, residual, small-wavevector nesting due to the electron dispersion in a lattice [1,2] and from competing interactions that can give rise to a series of transitions forming a Devil's Staircase [3]. Perhaps the most intriguing suggestion - and one that has most captured the imagination of condensed matter theorists of late - is that an itinerant system on the brink of a quantum phase transition might possess an intrinsic instability to the formation of modulated magnetic phases [4]. In any particular material, one or more of these effects may operate with the possibility of a complicated interplay between them.

This project aims to investigate the phenomenon of spatially modulated magnetism from both an experimental and theoretical perspective. We will use techniques of quantum many-body physics and field theory to investigate the possibility of spatially modulated magnetism in real systems. These investigations will be carried out in concert with neutron scattering experiments to provide inspiration for and validate this theory. The experimental part will include growing the crystals for these experiments as well as performing the measurements. We anticipate that a student will spend approximately 2/3 of their time on theory and 1/3 on experimental work, working both in Edinburgh and St Andrews as well as at international facilities.

[1] A. M. Berridge, A. G. Green, S. A. Grigera and B. D. Simons "A Magnetic Analogue of the of the FFLO state: Inhomogeneous Instabilities Near to Tricritical Points" Physical Review Letters 102, 149903 (2009).
[2] G. J. Conduit, A. G. Green, and B. D. Simons, "Inhomogeneous phase formation on the border of itinerant ferromagnetism" Physical Review Letters 103, 207201 (2009) [spotlighted in Physics 2, 93 (2009)]
[3] P. Bak & J. von Boehm, "Ising model with solitons, phasons, and 'the devil's staircase'", Phys Rev B 21 5297 (1980)
[4] J. Rech C.Pépin, V.Chubukov, "Quantum critical behaviour in intinerant electron systems: Eliashberg theory and instability of a ferromagentic quantum critical point" Phys Rev B 74 195126 (2006)
Finite-temperature behaviour of quantum Kasteleyn systems
Hooley, Dr Chris - cah19@st-andrews.ac.uk

Recent work on the so-called ‘spin ice’ materials [1] has produced a resurgence of interest in Kasteleyn transitions [2]. In a typical demagnetisation transition, the magnetism of a sample is reduced by the formation of local domains of flipped spins. In a Kasteleyn transition, however, these are effectively forbidden, and the transition is driven instead by the appearance of lines of flipped spins that extend all the way from one side of the sample to the other.
The standard theory of these transitions is purely classical, with the transition being driven by increasing temperature. But it is interesting to ask whether there is a quantum version of such a transition, driven by (for example) a transverse magnetic field [3]. If so, it should give rise to interesting finite-temperature phenomena: the Kasteleyn analogues of the quantum criticality observed in the conventional case [4].

The initial goal of this project is to determine whether a quantum Kasteleyn transition exists in a particular toy model [3], and then to develop a theory of the finite-temperature behaviour of the model in the vicinity of the quantum Kasteleyn point.

[1] C. Castelnovo, R. Moessner, and S.L. Sondhi, Nature 451, 42 (2008).
[2] L.D.C. Jaubert, J.T. Chalker, P.C.W. Holdsworth, and R. Moessner, Phys. Rev. Lett. 100, 067207 (2008).
[3] S.A. Grigera and C.A. Hooley, arXiv:1607.04657.
[4] S. Chakravarty, B.I. Halperin, and D.R. Nelson, Phys. Rev. B 39, 2344 (1989).

Category: Theoretical Hard Condensed Matter
Holographic traps and guides for superfluidity studies and atom interferometry
Cassettari, Dr Donatella - dc43@st-andrews.ac.uk

Holographic traps are a new kind of optical traps for neutral atoms which are promising for a wide range of applications, e.g. quantum information processing and quantum simulation. They are produced by diffracting a laser beam off a computer-controlled optical device, known as a Spatial Light Modulator (SLM). This apparatus offers unparalleled flexibility in the choice of trapping geometry, and different experiments can be done simply by reconfiguring the SLM.
In this PhD project you will work on:

- Double well traps for confined atom interferometry, which is promising for the development of sensitive devices (see [1] for a review).

- Ring-shaped atom guides (see [2] and [3]), which can be used to observe superfluid motion of a Bose-Einstein condensate, e.g. persistent current states. BECs in these geometries and the study of their critical velocities (where superflow stops) have very important technological applications in sensing devices, such as superconducting quantum interference devices (SQUIDs). Moreover, theoretical proposals have been put forward in which coherent superposition of different BEC flows can be used as qubits.

[1] http://rmp.aps.org/abstract/RMP/v81/i3/p1051_1
[2] http://prl.aps.org/abstract/PRL/v106/i13/e130401
[3] http://lanl.arxiv.org/abs/1008.2140
Holographic traps for the efficient production of Bose-Einstein condensates
Cassettari, Dr Donatella - dc43@st-andrews.ac.uk

Evaporative cooling is an essential stage in the creation of Bose-Einstein condensates (BECs) in atomic gases. Recently we suggested [1] that holographic optical traps can be used to increase the evaporation efficiency, leading to larger BECs. In this PhD project you will implement this scheme, which will result in a simplified apparatus for the productions and subsequent manipulation of BECs.

[1] http://pra.aps.org/abstract/PRA/v84/i5/e053410

Integrated Magnetic Resonance Doctoral Training Centre
Smith, Dr Graham - gms@st-andrews.ac.uk

The new EPSRC Doctoral Training Centre in Integrated Magnetic Resonance is a collaboration between 6 of the UK's leading Universities in Advanced Magnetic Resonance Instrumentation and Techniques and includes St. Andrews, Dundee, Aberdeen, Warwick, Nottingham and Southampton.

The aim is to provide a coherent training program for doctoral students whilst working on new research topics in instrumentation and methodology, associated with Magnetic Resonance Imaging, Electron Magnetic Resonance, Nuclear Magnetic Resonance and Dynamic Nuclear Polarisation (which collectively represent £multi-Billion annual markets). Training is delivered from all centres, through residential workshops and over the Access Grid, primarily in the first two years of study.

Funded 4 year PhDs include fees and maintenance of £14000 (tax free) per annum as well as an enhanced travel budget. All PhDs will have internal and external mentors from other centres.

At St Andrews, PhD projects are available on themes associated with major advances in Electron Magnetic Resonance and Dynamic Nuclear Polarisation and are likely to involve collaborations with other centres and other interdisciplinary groups.

PhD topics are likely to involve a combination of instrumental, methodological and computational techniques that would normally be associated with Basic Technology programs.

Representative PhDs from all 6 centres are listed on www.imr-cdt.ac.uk, but other PhD topics may be available on request.

For PhDs at St Andrews, applications can be made directly to St Andrews or via Warwick where the DTC program is administered.
Investigating novel superconducting ground states in nanofabricated hybrid ferromagnetic-superconducting materials and devices using advanced neutron, muon and synchrotron techniques
Lee, Prof Steve - sl10@st-andrews.ac.uk

The search for novel quantum states of matter in artificial thin-film structures, in which superconducting (S) and ferromagnetic (F) materials are juxtaposed, has reached an exciting and timely stage of development. In the last year a series of new landmark experimental results seem set to herald a period of rapid expansion of interest and activity in the field. This was the pioneering observation by several groups of spin-triplet supercurrents traversing relatively thick F layers [1-3], believed theoretically to be signatures of a novel equal-spin spin-triplet and possibly ‘odd frequency’ superconducting state. This achievement represent the culmination of several years of breakthrough experiments [1-7] in a field whose modern era began almost most a decade ago, with the experimental discovery of Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) [8] type states in S-F-S structures [10]. What both the FFLO [8] and the odd-frequency pairing phenomena [9] have in common is that they were predicted to occur theoretically in bulk systems [8,9] but only in state-of-the-art artificial thin-film structures were they finally demonstrated to exist [1-7,10-13]. Modern thin-film growth and large area lithographic patterning open-up an enormous range of further possibilities for engendering novel quantum states of matter via the controlled interaction S and F order on the nanoscale. This capability also offers the promise of designing and engineering hybrid metamaterials (in a similar spirit to electromagnetic metamaterials) with tailored quantum properties. Concurrently there is enormous interest in spintronics, the manipulation of electronic spin for application in novel electronic devices. The structures investigated within this programme marry the fields of mesoscopic superconductivity, novel strongly correlated electron physics and spintronics. By introducing quantum coherence phenomena into spintronic types devices, this also opens up the possibility of non-locality and entanglement, with possible application long-term in quantum computation.

Professor Steve Lee leads an EPSRC funded Critical Mass Grant award (St Andrews, Leeds, Bath, Royal Holloway, ISIS, with partners in PSI ( Swizterland), Cambridge, and Leiden ) that underpins an international research programme that brings together a team with a wide range of relevant expertise to explore the physics of such systems. We make use of some of the most powerful probes in condensed matter physics (scattering and surface probe techniques) in order to throw new light onto the physics of artificial S-F metamaterials, with particular emphasis on spatially–resolved measurements. This combines with state-of-the-art facilities for materials growth and patterning and world leading instrumentation for measurement. The programme is also informed by cutting-edge theory. There are significant opportunities for research students within this collaboration, with excellent access to world leading research facilities (such as Diamond, ISIS, ILL, PSI, SLS). Due to the strong interactions between nodes there is also significant scope for student mobility in order to enhance training and experience. This is all underpinned by access to excellent graduate training bot via the SUPA Graduate School and the additional benefits of the Doctoral Training Centre in condensed matter physics based at St Andrews, Edinburgh and Heriot Watt.

[1] J.W.A. Robinson et al., Science 329 59 (2010).
[2] T.S. Khaire et al., PRL 104, 137002 (2010).
[3] M.S. Anwar et al., PRB 82, 100501 (2010).
[4] R.S. Keizer et al., Nature 439 825 (2006).
[5] J. Wang et al., Nat. Phys. 6 389 (2010).
[6] I. Sosnin et al., PRL 96 157002 (2006).
[7] D. Sprungmann et al., PRB 82, 060505 (2010).
[8] P. Fulde and R.A. Ferrell, PRB 135 A550 (1964);
A.I. Larkin and Y.N. Ovchinnikov, Zh. Eksp.
Teor. Fiz. 47, 1136 (1964).
[9] V.L. Berezinskii, JEPT Lett. 20, 287 (1974).
[10] V.V. Ryazanov et al., PRL 86, 2427 (2001); T. Kontos et al., PRL 89, 137007 (2002).
[11] A.I. Buzdin et al., JETP Letters 35, 178 (1982);
[12] F.S. Bergeret et al., PRL 86, 4096 (2001); Rev. Mod. Phys. 77, 1321 (2005).
[13] M. Eschrig et al., PRL 90, 137003 (2003); M. Eschrig and T. Löfwander, Nature Phys. 4 138 (2008).


Magnetic measurements to probe unconventional superconductors
Huxley, Prof Andrew - ah311@st-andrews.ac.uk
Yelland, Dr Ed - eay1@st-andrews.ac.uk

Magnetism and superconductivity are intimately connected in many so-called heavy fermion metals. A particularly dramatic case is URhGe, where two distinct superconducting regions exist – one coexisting with ferromagnetism, and the other at extremely strong applied magnetic fields that are sufficient to destroy conventional forms of superconductivity. This project will involve developing sensitive magnetic measurement apparatus that will operate at extremes of low temperature, high magnetic field and high pressure, and apply them to study URhGe and other related materials. The aims are both to gain a deeper understanding of how magnetic pairing may lead to superconductivity and to drive the search for new superconducting materials. The project could be based in either St Andrews or Edinburgh.

The project is an integral part of a major research effort to study quantum criticality and unusual quantum ordered phases using a variety of magnetic, electrical and thermal measurement techniques. The apparatus in St Andrews includes a state-of-the-art dilution refrigerator (commissioned December 2007) with a base temperature 10 millikelvin and equipped with a 17 tesla magnet, that will allow coverage of a wide region of experimental parameter space, including applied pressures up to 100 kbar.

The focus for the project is on magnetic measurements including torque magnetometry, field gradient magnetometry and a.c. susceptibility. By combining torque and field-gradient results, the vector magnetic moment can be determined as a function of magnetic field and its angle to the crystallographic axes. This will allow a complete phenomenological (Ginzburg-Landau) description of the magnetism close to the superconducting phase to be constructed, and will provide detailed information about the nature of the magnetic interactions that are important for superconductivity. Another important component of the work will be to use quantum oscillations in various magnetic quantities to study the Fermi surface and how these change approaching and crossing quantum phase transitions.
Manipulating electron spins to explore structure in biomacromolecules.
Lovett, Dr Janet - jel20@st-andrews.ac.uk

Knowledge of the structure of and structural changes within biomacromolecules such as proteins or oligonucleotides (DNA, RNA) leads to advancing our understanding of the underlying mechanisms of function. Ultimately this is not only fundamentally interesting but will lead to improved drug targets and better biotechnology.

Electron paramagnetic resonance (EPR) spectroscopy is capable of measuring nanometre distances between stable radicals, such as nitroxyl-containing spin labels.[1] These spin labels can be attached site-selectively to proteins or nucleic acids, though naturally occurring paramagnetic centres can also be used.[2,3] For example, double electron electron resonance (DEER) is a pulsed EPR experiment that has proved useful for studying the structure of a range of biomacromolecules.1,4 Many of these experiments have been carried out in frozen glassy solutions. Your project would be to work on methods to expand the scope of the environment that biopolymers can be studied in through development of high-pressure,[5] room temperature[6] and in-cellular methods.[7]

The PhD will be run through the School of Physics and Astronomy at the University of St Andrews and you will also be a member of the Biological Sciences Research Complex. You must have a good scientific degree for example in a such as chemistry, biochemistry, biology or physics and be motivated to work across the disciplines.

The facilities at St Andrews for EPR, protein preparation and chemistry are outstanding, more information can be found at http://www.st-andrews.ac.uk/~jel20. Informal enquires are encouraged prior to application and should be made to Dr Janet Lovett (jel20@st-andrews.ac.uk).


1. Klare, J. P. and Steinhoff H.-J., (2009) Photosynth Res 102 377-390
2. Haugland, M. M., El-Sagheer, A. H., Porter, R. J., Pena, J., Brown, T., Anderson, E. A., Lovett, J. E., (2016) J. Am. Chem. Soc. 138 9069-9072
3. Motion, C. L., Lovett, J. E., Bell, S., Cassidy, S. L., Cruickshank, P. A. S., Bolton, D. R., Hunter, R. I., El Mkami, H., Van Doorslaer, S. and Smith, G. M., (2016) J. Phys. Chem. Lett. 7 1411-1415
4. Jeschke, G., (2012) Annu. Rev. Phys. Chem. 63 419-446
5. Lerch, M. T., López, C. J., Yang, Z., Kreitman, M. J., Horwitz, J. and Hubbell, W. L., (2015) Proc. Natl. Acad. Sci. E2437–E2446
6. Meyer, V., Swanson, M. A., Clouston, L. J., Boratyński, P. J., Stein, R. A., Mchaourab, H. S., Rajca, A., Eaton, S. S. and Eaton G. R., (2015) Biophys. J. 108 1213-1219
7. Igarashi, R., Sakai, T., Hara, H., Tenno, T., Tanaka, T., Tochio, H. and Shirakawa, M., (2010), J. Am. Chem. Soc. 132 8228-8229.

Funding

The studentship will be funded through EPSRC and as such successful applicants from the UK can be fully supported for 3.5 years though there are exceptions, please see https://www.epsrc.ac.uk/skills/students/help/eligibility/ . Funding is allocated depending upon availability and candidate quality so early applications are encouraged.

Citizens of China may be eligible for funding through the China Scholarship Council, https://www.st-andrews.ac.uk/study/international/csc/ . The internal deadline for applications to the School of Physics and Astronomy is the 23rd November 2016.

Mesoscopic unconventional superconductors and Fermi liquids
Mackenzie, Prof Andy - apm9@st-andrews.ac.uk

This project is offer in conjunction with Prof. Amir Yacoby at Harvard.

In this project, we aim to bridge the gap between two fields in which huge progress has been made over the past twenty years. In mesoscopic physics, the aim is to work with samples that are specially fabricated so that their physical size becomes comparable with one or more of the fundamental length scales of the underlying physics. In a metal this might be the mean free path, and in a superconductor it might be the coherence length or the penetration depth. So far, the vast majority of research into mesoscopic physics has been performed on traditional materials in which the electron-electron interactions are relatively weak. In parallel with these developments, equally rapid progress has been made on research into new materials with very strong electron-electron interactions, which lead to high quasiparticle masses and an exciting variety of metallic, superconducting and magnetic ground states. For technical reasons the two fields have advanced in parallel, with little cross-fertilisation of ideas and techniques. The goal of this jointly supervised project is to combine the different expertise of our two groups to bring strongly interacting electrons into the mesoscopic regime. You will work both in St Andrews and at the spectacular new Harvard Nanoscience Center, performing pioneering experiments on the fabrication and measurement of correlated electron mesoscopic devices.

(Jointly affiliated to both University of St Andrews and Max Planck Institute for the Chemical Physics of Solids, Dresden)



Microscopic Phase Coexistence: a Conformal Bootstrap Analysis
Hooley, Dr Chris - cah19@st-andrews.ac.uk

Consider a two-dimensional condensed matter system in which two different low-temperature phases are competing, i.e. where tuning some non-thermal parameter causes a transition from one to the other. For example, the competing phases might be the superfluid and solid phases in a film of helium-4 (the tuning parameter in this case being pressure), or the stripe-ordered and superconducting phases in a cuprate superconductor (with doping as the tuning parameter). Do we expect an abrupt first-order transition from one phase to the other, or might there be an intermediate range of parameters in which the system exhibits both types of order simultaneously? (I don’t mean phase separation, like bubbles of gas in a liquid – I mean that the phases coexist at the microscopic level.)

The answer to this question depends on the symmetry of the ordered phases in question, and in most cases it is known [1]. However, the case where both phases have O(2) symmetry is a more subtle one, and despite recent work [2] is not fully settled. In the past few years an exciting new theoretical tool has become available: the so-called ‘conformal bootstrap’ [3]. The initial aim of this project is to apply the bootstrap method to address the question of phase coexistence in the O(2)+O(2) case. Should this be achieved quickly, studies could be extended to non-zero temperature, where one would expect some interesting Kosterlitz-Thouless-like phase transitions [4,5].

[1] P. Calabrese, A. Pelissetto, and E. Vicari, Phys. Rev. B 67, 054505 (2003).
[2] A. Jaefari, S. Lal, and E. Fradkin, Phys. Rev. B 82, 144531 (2010).
[3] S. El-Showk et al., Phys. Rev. D 86, 025022 (2012).
[4] J.M. Fellows, S.T. Carr, C.A. Hooley, and J. Schmalian, Phys. Rev. Lett. 109, 155703 (2012).
[5] C.A. Hooley, S.T. Carr, J.M. Fellows, and J. Schmalian, JPS Conf. Proc. 3, 016018 (2014).

Category: Theoretical Hard Condensed Matter
Multimode cavity QED, beyond the superradiance paradigm
Keeling, Dr Jonathan - jmjk@st-andrews.ac.uk

Recent experiments on Bose--Einstein condensates in optical cavities have reported a quantum phase transition to a coherent state of the matter-light system -- superradiance[1]. This experiment, and related work following the theoretical proposal [2] has prompted much exploration of the possibilities of cavity QED with ultracold atoms as a venue to explore collective behaviour in open quantum systems.

While experiments on single mode cavities [1,2,3] have been studied extensively, experiments on multimode cavities [5] are only just beginning. These have the potential to transform the kinds of behaviour one can study. We have recently explored the idea of simulating dynamical gauge fields with such a system [6]. Other possibilities suggested include simulating Hopfiled associated memories (including potentially quantum extensions thereof), and liquid crystaline phases of matter. This PhD will explore a number of these topics; we will work in close collaboration with the Lev group in Stanford, so the precise projects will be determined in order to match ongoing and future experiments.


[1] K. Baumann, C. Guerlin, F. Brennecke, and T. Esslinger,
Nature 464, 1301 (2010)
[2] F. Dimer, B. Estienne, A. S. Parkins, and H. J.
Carmichael, Phys. Rev. A 75, 013804 (2007).
[3] M. J. Bhaseen, J. Mayoh, B. D. Simons, J. Keeling. Phys. Rev. A 85, 013817 (2012)
[5] A. J. Kollár, A. T. Papageorge, V. D. Vaidya, Y. Guo, J. Keeling, B. L. Lev
https://arxiv.org/abs/1606.04127
[6] K. E. Ballantine, B. L. Lev, Jonathan Keeling
http://arxiv.org/abs/1608.07246v1
Novel Quantum Order in Vector Magnetic Fields
Mackenzie, Prof Andy - apm9@st-andrews.ac.uk

Strongly interacting electron systems are one of the best hosts for study of the quantum many-body problem. Experimental discoveries made in the past decade show that, in the cleanest materials, a variety of subtle collective states form at low temperatures. Some of these are metallic but involve the development of a preferred direction, driven not by the crystal symmetry but by the electron-electron interactions themselves. To study anisotropic responses like these, careful experiments are necessary – they can easily be missed if the correct probes are not used. Many of the states discovered so far have a coupling to externally applied magnetic fields, so these fields can be used to ‘train’ the systems’ response functions. This has highlighted the need to develop better and better ‘vector magnets’ in which the field vector can be changed via computer-controlled energisation of multiple superconducting coils. On this project you will have access to world-leading instruments capable of generating 1, 1 and 9 tesla along the x, y and z axes. This will enable you to study transport and thermodynamic quantities that cannot be accessed in standard instruments. Using this unique instrumentation, you will have the chance to investigate a range of the most exciting new strongly correlated materials in a fast-moving field of modern research.

(Jointly affiliated to both University of St Andrews and Max Planck Institute for the Chemical Physics of Solids, Dresden)
Polaritons in organic semiconductor microcavities
Samuel, Prof Ifor - idws@st-andrews.ac.uk
Turnbull, Prof Graham - gat@st-andrews.ac.uk

When light is confined on the nanoscale it is possible to observe light-matter interactions that are not normally observed in bulk materials. One example is the strong coupling of photons and excitons in wavelength-scale microcavities which leads to a number of unusual phenomena [1,2]. The modes of the cavity couple with the exciton to make a hybrid-light-matter state called a polariton. One can make polaritons lasers that emit coherent light [3] and it has been shown that polaritons can form a Bose-Einstein condenstate [4].

This project will explore the properties of polaritons in microcavities based on organic semiconductors [2,4-6]. It will involve the fabrication of microcavities that include J-aggregate dyes or semiconducting polymers to explore how the energy states of organic materials can be modified when coupled to the cavity modes, and be applied in photonic devices including lasers and LEDs.

[1] C. Weisbuch et al., Phys. Rev. Lett. 69, 3314 (1992)
[2] D.G. Lidzey et al., Nature 395, 53 (1998)
[3] S. Christopoulos et al., Phys. Rev. Lett. 98, 126405 (2007)
[4] J D Plumhof, T Stöferle, L Mai, U Scherf & R F Mahrt, Nature Materials 13, 247–252 (2014)
[5] T. Schwartz, J. A. Hutchison, C. Genet, and T. W. Ebbesen, Phys. Rev. Lett. 106, 196405 –(2011)
[6] S Kéna-Cohen*, S A. Maier and D D. C. Bradley, Advanced Optical Materials 1, 827–833, (2013)
Quantum Electronic States in Delafossite Oxides
King, Dr Phil - pdk6@st-andrews.ac.uk

As part of a generously-funded ERC research project, we are seeking ambitious and motivated PhD students to join a major research initiative aimed at investigating Quantum Electronic States in Delafossite Oxides (QUESTDO). One of the most active challenges of modern solid state physics and chemistry is harnessing the unique and varied physical properties of transition-metal oxides. While little-studied to date, initial work suggests that the delafossite oxide metals are a particularly rich member of this materials class. They exhibit a wide array of fascinating properties, from ultra-high conductivity [1,2] to unconventional magnetism [3], with the potential to host strongly spin-orbit coupled states at their surfaces and interfaces. You will seek to understand, and control, the delicate interplay of frustrated triangular and honeycomb lattice geometries, interacting electrons, and effects of strong spin-orbit interactions in stabilising these. Projects are available: (i) utilizing laboratory-, laser-, and synchrotron-based angle-resolved photoemission to probe their intriguing bulk and surface electronic structures and many-body interactions; (ii) developing the epitaxial growth of delafossites by reactive-oxide molecular-beam epitaxy, using a state-of-the-art system recently installed in St Andrews; or (iii) working jointly between us and our research partners at the Max-Planck Institute for the Chemical Physics of Solids, Dresden, pursuing either single-crystal growth of new delafossites, or density-functional theory calculations of their electronic structures, combined with experimental studies in our group. For further information, or to discuss research possibilities, please contact philip.king@st-andrews.ac.uk. As part of this project, you will undertake experiments at national and international facilities. Thus, a willingness to travel is an essential prerequisite.

[1] Kushwaha et al., Science Advances 1 (2015) 1500692
[2] Moll et al., Science 351 (2016) 1061
[3] Ok et al., Phys. Rev. Lett. 111 (2013) 176405
Self-sustained topological phases in quasi-1D and 2D structures
Braunecker, Dr Bernd - bhb@st-andrews.ac.uk

Topological quantum phases have risen to a very active field of research recently, triggered mostly by the realisation that "ordinary" semiconductor nanostructures could be fine tuned to exhibit topological properties which are very attractive for quantum information storing and processing. With the link to semiconductors a major step forward has been taken towards a quantum technological implementation of such states, yet to obtain robust and scalable quantum systems the requirement of fine tuning has to be dropped.

Self-sustained topological phases provide such stable and robust systems, and exhibit a multitude of fascinating new physical properties that emerge as an effect of strongly interacting particles in a condensed matter system. We have already demonstrated that such phases spontaneously appear in hybrid magneto-electronic systems in one dimension [1-4]. Yet in 1D the number of topological states is restricted, and to obtain more exotic topological states extensions to higher dimensions must be made. It is, however, mandatory to maintain then the 1D self-sustaining mechanisms to avoid producing only conventional phases [5].

In this PhD project, we will take a systematic approach towards such self-sustained topological phases by enhancing the complexity of the systems step by step while maintaining full control over the strongly correlated electron state. We will investigate the influence of the lattice structure (square, honeycomb, kagome), anisotropies and frustration, as well as the crucial renormalisation of the system properties by electron interactions.

[1] B. Braunecker, P. Simon, and D. Loss, Phys. Rev. Lett. 102, 116403 (2009) [arXiv:0808.1685]
[2] B. Braunecker, P. Simon, and D. Loss, Phys. Rev. B 80, 165119 (2009) [arXiv:0908.0904]
[3] B. Braunecker and P. Simon, Phys. Rev. Lett. 111, 147202 (2013) [arXiv:1307.2431]
[4] B. Braunecker and P. Simon, Phys. Rev. B 92, 241410(R) (2015) [arXiv:1510.06339]
[5] P. Simon, B. Braunecker, and D. Loss, Phys. Rev. B 77, 045108 (2008) [arXiv:0709.0164]
The effects of non-adiabaticity and noise on quantum state preparation in cold-atom systems
Hooley, Dr Chris - cah19@st-andrews.ac.uk

One of the principal reasons for the current interest in ultracold atomic gases in optical lattices is the possibility they offer to prepare long-lived coherent quantum states 'to order'. This is usually done [1] by a sequence of protocols in which the various lasers creating the optical lattice are 'ramped' from one set of intensities to another, in a certain finite time.
The adiabatic theorem guarantees that, if this is done slowly enough, the system will remain in its ground state. However, in reality there are two problems with this. First, after a certain time - typically a few seconds - three-body collisions start to cause the atoms to escape from the trap. Second, there will inevitably be some noise in the lasers, meaning that the desired intensity as a function of time will not be precisely achieved.

The aim of this project is to deepen the theoretical study of how to optimise the laser ramp profiles for quantum state preparation. Specifically, we shall aim to determine what ramp profiles are optimal in the absence of laser noise, and how strongly the optimal ramp profiles are affected by noise of various sorts. A connection with Berry's transitionless quantum driving [2] presumably also exists; if so, it would be good to explore it.
[1] D. Greif, T. Uehlinger, G. Jotzu, L. Tarruell, and T. Esslinger, Science 340, 1307 (2013).
[2] M.V. Berry, J. Phys. A.: Math. Theor. 42, 365303 (2009)

Category: Theoretical Hard Condensed Matter
Theory of light emission with Berry curvature effects and strong light-matter coupling
Keeling, Dr Jonathan - jmjk@st-andrews.ac.uk

The basic principles of electroluminescence in semiconductors are well understood, but a number of recent experimental developments raise questions that are not fully answered. One example of this concerns transition metal dichalcogenides --- materials that have prompted significant interest due to "opto-spin-valley coupling", meaning that one can selectively excite particular conduction band states with spin polarisation by using the helicity of light. Experimentally, if one drives electrical currents through these devices, one finds circularly polarised light emission [1]. It is known that transport properties are influenced by strong Berry curvature effects leading to an effective magnetic field in momentum space changing signs between the two valleys. However, the effect of Berry curvature in light emission is yet to be explored.

Another example concerns electrically pumped polariton devices [2], where an optically active semiconductor quantum is placed in a microcavity, producing strong coupling between the photon and exciton modes. Some work on theories of this already exists [3,4], but many open questions remain.

The aim of this PhD project is to explore examples such as these, where it is necessary to develop and extend theories of electrical transport and electrical luminescence to understand how to control features such as circular polarisation, and strong matter-light coupling. This project will involve a mixture of analytical and computational work, with a substantial computational component.


This is a joint project with Dr Takashi Oka at the Max Planck Institute (PKS) Dresden. This is intended for students applying to the International Max Planck Research School scheme, which involves a joint programme between St Andrews and Dresden. See http://imprs-cpqm.mpg.de/ for further details

[1] Y. J. Zhang, T. Oka, R. Suzuki, J. T. Ye,, Y. Iwasa. Science 344 6185 (2014)
[2] Schneider et al, Nature 497 348 (2012)
[3] M. H. Szymanska, J. Keeling, and P. Littlewood. Phys. Rev. B 75 195331 (2007)
[4] M. Yamaguchi, K. Kamide, R. Nii, T. Ogawa, and Y. Yamamoto. Phys. Rev. Lett. 111 026404 (2013)
Topological Superconductivity
Mackenzie, Prof Andy - apm9@st-andrews.ac.uk

The concepts of symmetry and symmetry breaking cut across all sub-fields of physics. Whether crystal symmetry in solids, gauge symmetry in superconductors or time reversal symmetry in ferromagnets, we have become used to defining phases of matter in terms of order parameters associated with symmetry breaking. However, not all collective quantum states can be fully characterised in terms of their symmetries. In some systems phases are classified in terms of their topological characteristics. Although this has been known for several decades, it was thought to apply in highly restricted circumstances. Exciting and rapid developments over the past five years have shown that these topologically characterised phases are likely to be much more widespread than first thought, and that, in the long term, it may be possible to exploit their properties in adventurous new technologies. Although progress has been rapid, fascinating theoretical questions remain, not least the interplay between symmetry and topology. The field is also ripe for experimental study. Superconductors are among the most fascinating candidates for topological systems. A host of intriguing theoretical proposals exist, but the extent to which they are observable in practice has yet to be determined. This project is concerned with investigating candidate topological superconductors, using a combination of the world-leading experimental facilities in St Andrews, Dresden and Cornell. The project is ambitious, and would be best suited to a candidate with both experimental and theoretical aptitude.

(Jointly affiliated to both University of St Andrews and Max Planck Institute for the Chemical Physics of Solids, Dresden)
Ultrafast Photophysics of Organic Semiconductors
Samuel, Prof Ifor - idws@st-andrews.ac.uk

This project will explore the physics of remarkable plastic-like semiconductors, such as light-emitting polymers. These materials are model one-dimensional systems and this strongly influences their physics – for example it means that excitons are strongly bound and that there is a substantial distortion of the material when it is excited. The purpose of this project is to study the nature of the excited states in these materials and how they evolve when the sample is excited by light. The initial rearrangement of the molecules occurs on a timescale of 100 femtoseconds. Remarkably we can make measurements on this timescale using advanced femtosecond lasers. We wish to explore how the excited states form and then decay, and how these processes relate to the structure of the material. The results will help understand light emission and amplification, and complementary theoretical work is underway at Heriot-Watt University by Prof. Ian Galbraith.