Ultra-thin topological insulator spin-current transistor

Topological insulators are an existing class of band-gap insulators, whilst they do conduct through their edge (or the surface in the case of 3 dimensional materials). These gapless metallic surface states are naturally generated with helically-polarized spin texture due to strong spin-orbit coupling with a peculiar energy band structure of materials. Moreover the states are protected by time-reversal symmetry simply due to prohibition of back scattering and realize almost dissipationless pure spin currents (no net charge current) at the edge (surface) of materials. Spin-current devices based on the topological insulators save energy because it requires small current that flow at the edge (the surface) not in the bulk to access their surface properties.<br /> <br /> In this project, we will fabricate a spin-current field effect transistor with an ultra-thin topological insulator Bi2-xSbxTe3 film1 grown by molecular beam epitaxy in ultrahigh vacuum, a part of a new multi-deposition system in Leeds. Existence of gapless states in topological insulators are one of peculiar characteristics but we will open a gap in the surface state by employing ultra-thin films where the top and bottom surface states get unstable due to an interference between two. The gapped surface state with a gating technique will provide us a capability of fabricating a spin-current filed effect transistor that can switch on/off the spin-polarized current. We will also keep our eye on other topological insulator materials suitable for this device project.<br /> <br /> This is a project in an exciting and very active research area which allows us to closely interact and collaborate with other research teams in the University of Leeds including a theoretical group. We are looking for a motivated student with a background in physics, physical chemistry, or material science.

<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 of Study that you are applying for <em><strong>PHD Physics &amp; Astronomy&nbsp;FT</strong></em> and in the research information section&nbsp;that the research degree you wish to be considered for is<em><strong> Ultra-thin topological insulator spin-current transistor</strong></em>&nbsp;as well as <a href="https://physicalsciences.leeds.ac.uk/staff/131/dr-satoshi-sasaki">Dr Satoshi Sasaki</a> as your proposed supervisor.</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 style="margin-bottom:11px"><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> <li>Funding information including any alternative sources of funding that you are applying for or if you are able to pay your own fees and maintenance</li> </ul> <p>&nbsp;</p>

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 style="margin-bottom:12px"><strong>Self-Funded or externally sponsored students are welcome to apply.</strong></p> <p><strong>UK</strong>&nbsp;&ndash;&nbsp;The&nbsp;<a href="https://phd.leeds.ac.uk/funding/209-leeds-doctoral-scholarships-2022">Leeds Doctoral Scholarships</a> and <a href="https://phd.leeds.ac.uk/funding/234-leeds-opportunity-research-scholarship-2022">Leeds Opportunity Research Scholarship</a> are available to UK applicants. The&nbsp;<a href="https://phd.leeds.ac.uk/funding/102-bell-burnell-scholarship-award-awarded-by-the-iop">Bell Burnell Scholarship Award</a>&nbsp;is available to support applicants who are from groups that are currently under-represented in physics (awarded by the IOP).&nbsp; <a href="https://phd.leeds.ac.uk/funding/60-alumni-bursary">Alumni Bursary</a> is available to graduates of the University of Leeds.</p> <p><strong>Non-UK</strong> &ndash; The&nbsp;<a href="https://phd.leeds.ac.uk/funding/102-bell-burnell-scholarship-award-awarded-by-the-iop">Bell Burnell Scholarship Award</a>&nbsp;is available to support applicants who are from groups that are currently under-represented in physics (awarded by the IOP).&nbsp; &nbsp;The&nbsp;<a href="https://phd.leeds.ac.uk/funding/48-china-scholarship-council-university-of-leeds-scholarships-2021">China Scholarship Council - University of Leeds Scholarship</a>&nbsp;is available to nationals of China. The&nbsp;<a href="https://phd.leeds.ac.uk/funding/73-leeds-marshall-scholarship">Leeds Marshall Scholarship</a>&nbsp;is available to support US citizens. <a href="https://phd.leeds.ac.uk/funding/60-alumni-bursary">Alumni Bursary</a> is available to graduates of the University of Leeds.</p> <p><strong>Important:&nbsp;</strong> Any costs associated with your arrival at the University of Leeds to start your PhD including flights, immigration health surcharge/medical insurance and Visa costs are <strong>not </strong>covered under these studentships.</p> <p>Please refer to the <a href="https://www.ukcisa.org.uk/">UKCISA</a> website for information regarding Fee Status for Non-UK Nationals.</p>

<p>For further information about your application, please contact Doctoral College Admissions: e:&nbsp;<a href="mailto:EMAIL@leeds.ac.uk">m</a><a href="mailto:maps.pgr.admissions@leeds.ac.uk">aps.pgr.admissions@leeds.ac.uk</a></p> <p>For further information rabout this project, please Dr Satoshi Sasaki: e:&nbsp;&nbsp;<a href="mailto:S.Sasaki@leeds.ac.uk">S.Sasaki@leeds.ac.uk</a></p>