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Strain control of ferrimagnets


Key facts

Type of research degree
Application deadline
Ongoing deadline
Project start date
Sunday 1 October 2023
Country eligibility
International (open to all nationalities, including the UK)
Competition funded
Source of funding
University of Leeds
Dr Thomas Moore
Additional supervisors
Prof Andrew Bell
School of Physics and Astronomy
Research groups/institutes
Condensed Matter
<h2 class="heading hide-accessible">Summary</h2>

Magnetic random access memory (MRAM) using electrical current to switch magnetic layers has been on the market for around 5 years. It has the potential to replace much of the memory hierarchy in computer architectures but the device footprint and energy consumption are still too large to be competitive. To address the latter, there are several ongoing investigations into the use of electric field to manipulate nanomagnets, either by directly applying a gate voltage or indirectly via piezoelectric strain. Along with this has come an interest in the physics of interfaces of magnetic layers with other materials such as ferroelectrics, oxides and topological insulators. In previous work we have pioneered the piezoelectric strain control of ultrathin ferromagnetic layers with perpendicular magnetization (relevant to perpendicular magnetic recording, for example), and we have begun to explore the influence of strain at the surface of ferroelectric barium titanate on the magnetic domain structures in adjacent ferromagnetic layers. The use of a single crystal ferroelectric enables larger strain to be generated at the interface where it is needed, in contrast to commercial piezoelectric stressors where the surfaces are too rough to deposit high quality magnetic layers. The aim of this project is to replace the ferromagnet with a ferrimagnet, which has a smaller net magnetization making it promising, for example, for fast and efficient read/write operations, and which in the right composition has a peculiar sensitivity to strain. Ferrimagnet/ferroelectric structures will be grown in the Royce deposition facility at the University of Leeds, which combines several thin film growth techniques in one system, and characterised using state-of-the-art instruments in the Condensed Matter group. The goal will be to control the magnetic properties of the ferrimagnet reversibly by applying a voltage to the ferroelectric. The choice of materials will be guided by the principle of sustainability, ensuring that they are plentiful, as defined by the European Chemical Society in 2019. This requirement is already met by the constituent elements of barium titanate and some ferrimagnets too.

<h2 class="heading">How to apply</h2>

<p>Formal applications for research degree study should be made online through the&nbsp;<a href="">University&#39;s website</a>. Please state clearly in the Planned Course of Study thatyou are applying for <em><strong>PHD Physics &amp; Astronomy FT</strong></em> and in the research information section&nbsp;that the research degree you wish to be considered for is <em><strong>Strain control of ferrimagnets</strong></em>&nbsp;as well as&nbsp;<a href="">Dr Thomas Moore</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>

<h2 class="heading heading--sm">Entry requirements</h2>

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.

<h2 class="heading heading--sm">English language requirements</h2>

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.

<h2 class="heading">Funding on offer</h2>

<p style="margin-bottom:12px"><strong>Self-Funded or externally sponsored students are welcome to apply.</strong></p> <p>UK&nbsp;&ndash;&nbsp;The&nbsp;<a href="">Leeds Doctoral Scholarships</a> and <a href="">Leeds Opportunity Research Scholarship</a> are available to UK applicants. The&nbsp;<a href="">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="">Alumni Bursary</a> is available to graduates of the University of Leeds.</p> <p>Non-UK &ndash; The&nbsp;<a href="">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="">China Scholarship Council - University of Leeds Scholarship</a>&nbsp;is available to nationals of China. The&nbsp;<a href="">Leeds Marshall Scholarship</a>&nbsp;is available to support US citizens. <a href="">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="">UKCISA</a> website for information regarding Fee Status for Non-UK Nationals.</p>

<h2 class="heading">Contact details</h2>

<p>For further information about your&nbsp;application, please contact Doctoral College Admissions:&nbsp;e:&nbsp;<a href=""></a></p> <p>For further information about this project, please contact Dr Thomas Moore: e:&nbsp;<a href=""></a></p>