Ph.D. Research Projects
Every year at least one studentship is available for a suitably qualified applicant to join our Group. Early applications for places are strongly encouraged. Details of the projects currently available are given below. For more details of the kind of work carried out by the students in our Group please refer to the Ph.D current research projects page.
Ph.D. Project Titles - Funded Projects
Funded Project - Skyrmionic Materials ***POSITION FILLED***
Supervisor: Professor Geetha Balakrishnan
Funded Project - Quantum Materials Under Extreme Conditions ***POSITION FILLED***
Supervisor: Paul Goddard
The exploration of new and exotic states of matter is as fundamental to our grasp of the inner workings of the universe as is the detection of elementary particles or the discovery of celestial objects.
Nonetheless, many of today's most interesting, innovative and potentially useful materials display states of matter that seem to be explicable only by applying quantum mechanical models that are on the edge of our current understanding.
|Examples of low-dimensional quantum materials: (a) Na2IrO3 is a layered magnet with a honeycomb structure that is a potential realization of the much soughtafter Kitaev model of magnetism ; (b) the critical temperature of certain iron-based superconductors for some reason increase by a factor of of up to five after intercalation of molecules between the conducting layers [2,3]. (c) Quantum oscillations measured at low temperatures and in ultra high magnetic elds can be used to elucidate Fermi surface properties. The data shown here is for a high-temperature superconductor .|
This is perhaps unsurprising as these materials can be host to a complex medley of ingredients that include many-body interactions between spins, electrons and phonons. The ground states that emerge from this complexity frequently exhibit cooperative properties (superconductivity, Bose-Einstein condensation, charge or spin-order, multiferroicity) or exotic excitations (fractional excitations and composite fermions, anyons, magnetic monopoles, skyrmions, Majorana fermions). Besides the fundamental interest in understanding such materials, there is also the prospect of controlling their properties and putting them to use. Potential applications include ecient electrical power generation, transmission and storage; fast and secure communications; medical imaging and treatment; architectures for processing and caching quantum information; and compact solid-state devices, sensors and actuators. For these reasons, deciphering what causes quantum states of matter to form remains one of the most pressing challenges facing modern physics.
This fully funded PhD project is part of a larger program of work supported by the European Research Council, which aims to advance our knowledge of these states by using extreme conditions of magnetic eld and pressure to enable a continuous, clean and reversible tuning of quantum interactions, thereby shedding light on the building blocks of exotic magnetism and unconventional superconductivity.
The project takes as its starting point recent theoretical and experimental discoveries in the area of quantum materials. In particular, we will focus on a selected series of materials, both low-dimensional magnetic systems and unconventional superconductors, that are on the verge of a phase instability. Ultra-high elds and applied pressure will push these systems through the critical region where the state of matter changes and inherently quantum eects dominate. Electronic, magneticand structural properties will be measured as the tipping point is breached and the resulting data compared with predictions of theoretical models. We hope that the results will provide answers to questions of deep concern to modern physics, such how quantum fluctuations, topology and disorder can be used to create states of matter with fascinating and functional properties.
 P. Gegenwart and S. Trebst, Nature Physics 11, 444 (2015).
 M. Burrard-Lucas et al., Nature Materials 12, 15 (2013).
 F. Foronda et al., Physical Review B 92, 134517 (2015).
 S. Sebastian et al., Nature 511, 61 (2014).
Other Ph.D. Project Titles
Frustration in Magnetic Oxides
Supervisor Martin Lees, Co-supervisor Oleg Petrenko
In simple magnetic materials the magnetic behaviour is usually governed by the strength and sign of the interactions between the magnetic moments in the system. In frustrated magnets the competing interactions between the moments cannot all be satisfied simultaneously.
Studies of frustrated magnetic oxides have resulted in the discovery of some exciting new physics including spin ice and monopoles (see Fig. 1). Many of these breakthroughs have opened new avenues of research, while others have raised important questions that remain unanswered. It is the physics of these systems that will be the focus of this project. For some of our recent work please see Refs. 1 to 3.
|In this project, you will use image furnaces to grow high quality single crystals of oxide materials. The structural properties of these frustrated materials will be studied using a suite of state-of-the-art x-ray spectrometers and electron microscopes. You will examine the magnetic properties of these crystals in the laboratory at low temperatures and in high magnetic fields. You will also use a range of neutron scattering and muon spectroscopy techniques at national and international central facilities to investigate the physics of these materials.||Fig. 1. Phase diagram as a function of temperature T and the relative strength of the planar and Ising exchange for some pyrochlore titanates. Ho2Ti2O7 and Dy2Ti2O7 are spin ice while Yb2Ti2O7 undergoes a first-order transition from a Coulomb liquid to a Higgs phase of magnetic monopoles .|
This experimental project will offer an excellent training in several important aspects of modern condensed matter physics.
 L.-J. Chang, S. Onoda, Y. Su, Y.-J. Kao, K.-D. Tsuei, Y. Yasui, K. Kakurai, M. R. Lees, Nature Communications 3, 992 (2012).
 L.-J. Chang, M. R. Lees, I. Watanabe, A. D. Hillier, Y. Yasui, S. Onoda, Physical Review B 89, 184416 (2014).
 E. Lhotel, S. R. Giblin, M. R. Lees, G. Balakrishnan, L. J. Chang, Y. Yasui, Physical Review B 89, 224419 (2014).
Supervisor Geetha Balakrishnan, Co-supervisor Martin Lees
Topological Insulators (TIs) have been hailed as a new state of matter. TIs are materials that are insulating in the bulk, but exhibit special surface states that are conducting and topologically protected-i.e. the spin-orbit coupling in these materials leads to the formation of surface states that cannot be destroyed by scattering or impurities. Following the discovery of topological behaviour in the 2-D HgTe systems, several new 3-D materials exhibiting topological behaviour have been discovered. The 3-D TIs are thought to hold immense potential and have been likened to graphene in their surface electronic properties, with great promise for technological applications in areas such as thermoelectrics, electronics, spintronics and quantum information processing to name just a few.
Although the TIs have gapless edge or surface states that are protected, and an insulating gap in the bulk, most of the 3-D TIs discovered to date are still fairly conducting in the bulk. The challenge has been to create TI materials that are true insulators in the bulk in order to enable the study of their exotic surface states. Materials design and preparation has emerged as being key to the investigation and the discovery of new and better TIs.
The study will involve the synthesis of high quality TIs and characterisation of the bulk properties to understand their importance in influencing the surface states. Emphasis will be placed on the investigation of the structural aspects, information from which will be used to design and fabricate potential materials with TI behaviour. The project will also involve work on several Topological Crystalline Insulators (TCIs), Topological Kondo Insulators as well as TIs that are superconductors, exhibiting a full pairing gap in the bulk and gapless surface states, in analogy with the TIs. Some experimental work on the production and study of new TIs/TCIs in the form of nanomaterials will also be attempted.
The project is part of a new EPSRC funded programme on Topological Insulators. The student will be offered valuable training in the synthesis, in-house characterisation and the use of neutrons and muons at central facilities for the study of the interesting properties exhibited by TIs. The student will also have the opportunity to be involved in several collaborations, both within Warwick (Electron microscopy, Structural studies, NMR and Nanoscience) and with various groups outside Warwick to perform ARPES and other experiments to investigate the exotic surface properties of these materials.
This is a new, exciting and fast moving field and an ideal project for a strong and enthusiastic student.
Click here for more details of the formal application procedures, the relevant application forms and a postgraduate prospectus. N.B. This information is mounted on the Physics Department web pages outside this Superconductivity and Magnetism site.
M.Sc. Research Projects
We always have places available for suitably qualified self-funded students who would like to work towards an M.Sc. For more details of the kind of work carried out by the students in our Group please refer to the current postgraduate research projects page.
M.Sc. Project Titles
Topological Insulators: Investigation of the bulk properties of new topological insulators and superconductors.
Supervisor Geetha Balakrishnan
Click here for more details of the formal application procedures, the relevant application forms and a postgraduate prospectus. Note, this information is mounted on the Physics Department web pages outside this Superconductivity and Magnetism site.
We are sorry, at present the Superconductivity and Magnetism Group has no funded vacancies for post doctoral research staff.
If you are planning to apply for a fellowship (please see right for details of several schemes available to postdoctoral researchers) and you would like to discuss the possibility of us acting as your host institution please do not hesitate to contact us.
At the moment the Superconductivity and Magnetism Group has no vacancies for Technical Staff.
You may like to view the Warwick University Human Resources Office web page with a listing of all the jobs that are currently available here at the University.
Current vacancies at universities throughout the U.K. are listed on the jobs.ac.uk web site.
Experimental Studies of Noncentrosymmetric Superconductors
Supervisor Martin Lees, Co-supervisor Geetha Balakrishnan
The discovery of superconductivity by Kamerlingh Onnes over 100 years ago has offered physicists the opportunity to study this most intriguing macroscopically coherent state of electrons. For “conventional” superconductors the Cooper pairs are s-wave, while in “unconventional” materials the pair wavefunction may be an odd-parity spin-triplet.
In noncentrosymmetric crystal structures, i.e. systems without inversion symmetry, parity is no longer a meaningful label. The lack of inversion symmetry induces an antisymmetric spin-orbit coupling which can lift the degeneracy of the conduction band electrons and may cause the superconducting pair wavefunction to contain a mixture of singlet and triplet spin states. The breakdown of the usual classification of superconductors into even and odd-parity states means that a variety of physical effects that may previously have been forbidden are now allowed. Examples include exotic superconducting gap structures (lines or nodes in the superconducting gap), magnetoelectric effects such as a helical phase and upper critical fields exceeding the Pauli limiting fields, time reversal symmetry breaking, and even topological effects. For some of our recent work in this field please see References. 1-3.
In this experimental project, you will study the superconducting properties of this fascinating class of materials. Single crystal samples will be grown. Their structural properties will be studied using a suite of state-of-the-art x-ray spectrometers and electron microscopes. You will then examine the superconducting properties of these crystals in the laboratory at low temperatures and in high magnetic fields. A range of neutron scattering and muon spectroscopy techniques available at national and international central facilities will also be used to investigate the physics of these materials.
This experimental project will offer an excellent training in several important aspects of modern condensed matter physics.
 R. P. Singh, A. D. Hillier, B. Mazidian, J. Quintanilla, J. F. Annett, D. M. Paul, G. Balakrishnan, M. R. Lees, Physical Review Letters 112, 107002 (2014).
 R. P. Singh, A. D. Hillier, D. Chowdhury, J. A. T. Barker, D. M. Paul, M. R. Lees, G. Balakrishnan, Physical Review B 90, 104504 (2014).
 M. Smidman, A. D. Hillier, D. T. Adroja, M. R. Lees, V. K. Anand, R. P. Singh, R. I. Smith, D. M. Paul, G. Balakrishnan, Physical Review B 89, 094509 (2014).
Click here to see a more details of the Ph.D. projects available here in the Physics Department at Warwick.
Post Doctoral Research Staff
If you are planing to make an application for a Fellowship scheme, including any of those listed below, please do not hesitate to contact us.
Other funding opportunities for postdoctoral staff
Marie-Curie fellowships (European Union funding)
Royal Society fellowships
Humboldt Foundation - Feodor Lynen fellowships (for German Post-docs)
closing dates: 10th February, 10th June, and 10th October