Defects, Disorder and Dynamics in Topological Insulators and the Implications for Functional Next Generation Quantum Devices

Topological insulators (TIs) are an emerging class of materials that are generating considerable interest worldwide with potential for many device applications as part of next generation quantum technologies. To enable this, it is necessary to develop a detailed understanding of how the specific growth conditions affect the final properties of these materials. This project will apply solid-state density functional theory calculations and advanced ab-initio MD methods to explore the influence of structural ordering on the anharmonicity of bulk phonon properties of these materials. When coupled with experimental data, this project with apply the result to further train neural network based machine learning models, with the aim of developing predictive tools for the rational design of future materials.

<p>Topological insulators (TIs) are an emerging class of materials that are generating considerable interest worldwide with potential for many device applications as part of next generation quantum technologies. Key to the future application of these materials is to understand how growth conditions, alloy fraction, defects and doping influence both the bulk and protected surface states of the materials, properties that are crucial to understand in order to design and develop next generation quantum technologies based on these materials.</p> <p>Here we will extend our previous work [1] that used solid-state density functional theory calculations to explore the influence of structural ordering on the anharmonicity of bulk phonon properties of these materials. We propose to look at larger systems with the addition of other dopants which have shown potential in future devices. We plan to extend methods of exploring the influence of dopants and the stability of specific defect states using methods that were recently developed [2] for other materials including semiconductors, perovskites and photovoltaics. These will be crucial in exploring the energy landscape of these materials and feed into the rational design of materials with specific properties needed to create next generation devices.</p> <p>Furthermore we will use advanced ab-initio MD methods we have been developing for organic crystals [3] which allows for a much greater understanding of the influence of anharmonicity and coupling between phonon modes and the influence of this on both the thermodynamic and extended properties of these materials.</p> <p>These calculations will be used to underpin the experimental work on these materials that is already happening within the group, aiding its interpretation while providing guidance for future growth criteria for improved material properties. Finally, we will couple the calculated results with experimental data to train neural network based machine learning models, which we hope to be able to use as predictive tools for future rational design of future materials.</p> <p>References:</p> <p>[1] C.S. Knox et al Effects of structural ordering on infrared active vibrations within Bi2(Te(1&minus;x)Sex)3.</p> <p>PRB 106, 245203, 2022.</p> <p>[2] Mosquera-Lois, I. et al. ShakeNBreak: Navigating the defect configurational landscape, Journal</p> <p>of Open Source Software 7 (80), 4817, 2022.</p> <p>[3] J. Kendrick et al Exploring the Stability and Disorder in the Polymorphs of L-Cysteine through</p> <p>Density Functional Theory and Vibrational Spectroscopy Cryst. Growth Des.23 (8), 5734&ndash;5747,</p> <p>2023</p>

<p>Formal applications for research degree study should be made online through the&nbsp;<a href="https://www.leeds.ac.uk/research-applying/doc/applying-research-degrees">University&#39;s website</a>. Please state clearly in the Planned Course for Study section that you are applying for <em><strong>EPSRC DTP Engineering &amp; Physical Sciences</strong></em>, in the research information section&nbsp;that the research degree you wish to be considered for is <em><strong>Defects, Disorder and Dynamics in Topological Insulators and the Implications for Functional Next Generation Quantum Devices</strong></em> as well as&nbsp;<a href="https://eps.leeds.ac.uk/chemistry/staff/4211/dr-andrew-burnett">Dr Andrew Burnett </a>as your proposed supervisor and <em><strong>in the Finance section, please state that the funding source you are applying for is EPSRC Quantum Technologies&nbsp;Doctoral Training Studentship.</strong></em></p> <p>If English is not your first language, you must provide evidence that you meet the University&#39;s minimum English language requirements (below).</p> <p><em>As an international research-intensive university, we welcome students from all walks of life and from across the world. We foster an inclusive environment where all can flourish and prosper, and we are proud of our strong commitment to student education. Across all Faculties we are dedicated to diversifying our community and we welcome the unique contributions that individuals can bring, and particularly encourage applications from, but not limited to Black, Asian, people who belong to a minority ethnic community, people who identify as LGBT+ and people with disabilities. Applicants will always be selected based on merit and ability.</em></p> <p class="MsoNoSpacing">Applications will be considered on an ongoing basis. &nbsp;Potential applicants are strongly encouraged to contact the supervisors for an informal discussion before making a formal application. &nbsp;We also advise that you apply at the earliest opportunity as the application and selection process may close early, should we receive a sufficient number of applications or that a suitable candidate is appointed.</p> <p>Please note that you must provide the following documents at the point you submit your application:</p> <ul> <li>Full Transcripts of all degree study or if in final year of study, full transcripts to date</li> <li>Personal Statement outlining your interest in the project</li> <li>CV</li> </ul>

Applicants to research degree programmes should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline. The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid. Some schools and faculties have a higher requirement.

<p>A highly competitive EPSRC Quantum Technologies Doctoral Training Partnership Studentship offering the award of fees, together with a tax-free maintenance grant of &pound;19,237 per year for 3.5 years.&nbsp; Training and support will also be provided.<br /> <br /> This opportunity is open to UK applicants only.<br /> <br /> Please refer to the&nbsp;<a href="https://www.ukcisa.org.uk/">UKCISA</a>&nbsp;website for&nbsp;information regarding Fee Status for Non-UK Nationals.</p>

<p>For further information regarding your application, please contact Doctoral College Admissions by email to <a href="mailto:phd@engineering.leeds.ac.uk">phd@engineering.leeds.ac.uk</a></p> <p>For further information regarding this project, please contact Dr Andrew Burnett by email to <a href="mailto:A.D.Burnett@leeds.ac.uk">A.D.Burnett@leeds.ac.uk</a></p> <p>For information about Quantum Technologies or the Bragg Centre for Materials Research, please email <a href="mailto:BraggCentre@leeds.ac.uk">BraggCentre@leeds.ac.uk</a>.</p>