Optical detection of magnetization dynamics induced by spin-orbit torques. Physics - PhD (Funded) Ref: 2463

About the award

Location: Streatham Campus, University of Exeter, EX4 4QJ

Primary Supervisor: Professor R. J. Hicken

Secondary Supervisor: Dr P. S. Keatley

Project Description:

The injection of electrical current into multilayered magnetic materials can generate spin-orbit torques (SOTs) capable of modifying the magnetic state. The use of SOTs provides new opportunities for writing data in magnetic random access memory (MRAM), exciting precession in spin transfer oscillators (STOs), and driving magnetic objects such as domain walls, vortices and skyrmions.  However, the contribution made by different underlying microscopic mechanisms, such as the spin Hall and Rashba effects, to the observed SOTs remains controversial.  This is because firstly, SOTs are sensitive to atomic scale structural features, and secondly, conventional electrical measurement techniques offer limited access to the detailed magnetic state. 

A PhD studentship is available in conjunction with a new EPSRC funded project (EP/P008550/1) in which time resolved scanning Kerr microscopy (TRSKM) will be used to quantify SOTs in planar devices for which the physical structure, particularly at the interfaces, has been carefully characterized. This internationally unique optical measurement technique will allow the magnetization to be probed directly for the first time, without reliance on electrical measurements, and with nanoscale spatial resolution.  The SOTs will be quantified through measurements of both the static orientation of the vector magnetization, and its precession.  Using the same TRSKM, time resolved measurements will be made of SOT induced switching when a pulsed current is applied, and of the steady state precession that may be induced by a constant current.  Crucially, the measurements will determine the spatial character of these processes, revealing the interplay between SOTs and the resonant mode spectrum of a specific sample or device geometry.  We will hence gain insight into how SOTs may be manipulated and best exploited in device operation.

You will be part of an international collaboration in which samples and devices of the highest quality are obtained from HGST in San Jose California, Brown University in Rhode Island, and the University of Gothenburg.  There is potential for travel to the partner sites to build understanding of sample fabrication and for discussion of results.  You will also be expected to present the results of your research at international conferences.  PhD funding is available for 42 months. 

Contact for informal enquiries: For more information about the project and informal enquiries, please contact the primary supervisor, Professor R. J. Hicken

This award provides annual funding to cover UK/EU tuition fees and a tax-free stipend.  For students who pay UK/EU tuition fees the award will cover the tuition fees in full, plus at least £14,553 per year tax-free stipend.  Students who pay international tuition fees are eligible to apply, but should note that the award will only provide payment for part of the international tuition fee and no stipend. 

The studentship will be awarded on the basis of merit for 3.5 years of full-time study to commence as soon as possible.

Application criteria:

Applicants for this studentship must have obtained, or be about to obtain, a First or Upper Second Class UK Honours degree, or the equivalent qualifications gained outside the UK, in a physics based discipline and have experience of condensed matter physics, electromagnetism and optics. 


If English is not your first language you will need to have achieved at least 6.5 in IELTS and no less than 6.0 in any section by the start of the project.  Alternative tests may be acceptable (see http://www.exeter.ac.uk/postgraduate/apply/english/).

Summary

Application deadline:17th September 2017
Number of awards:1
Value:UK/EU Tuition fees and an annual maintenance allowance of £14,553
Duration of award:per year
Contact: Postgraduate Research Officeemps-pgr-ad@exeter.ac.uk

How to apply

To apply, complete the online form. You will be asked to submit some personal details and upload a full CV, covering letter and details of two academic referees. Your covering letter should outline your academic interests, prior research experience and reasons for wishing to undertake this project. 

You may also be asked to upload verified transcripts of your most academic qualification.

Interviews will be held at Streatham Campus in late September 2017.

Please quote reference 2463 on your application and in any correspondence about this studentship.