EPSRC CDT in Metamaterials (PhD studentship): A quantum thermodynamic study to improve magnetic data storage

University of Exeter - Departments of Physics and Engineering

Joint supervisors: Dr Janet Anders, Dr Simon Horsley, Prof Robert J Hicken

This is a theoretical PhD project within the CDT in Metamaterials, University of Exeter, to start autumn 2018.  http://emps.exeter.ac.uk/metamaterials/

The critical components of magnetic hard drives have been continually scaled down in size. The magnetic grains, which store the information, are now pushing below 8nm and further miniaturization faces new challenges.  Notably, magnetically hard materials are required to ensure thermal stability of the information encoded in these small bits.  But the magnetic write-fields in recording heads are no longer strong enough to switch them.  Heat-assisted magnetic recording (HAMR) has been proposed as a candidate technology that would enable the switching of grains by providing additional energy in form of heat delivered by a laser diode in the recording head. The effective inclusion of such laser diodes in the recording head is being actively developed by industry [1]. However, problems with the standard theoretical tools describing the writing process have now surfaced and require a fundamental rethink [2] that goes well beyond industry's capability.

This project is concerned with the application of new theoretical tools from the field of quantum thermodynamics to the problem of collections of spins that are subject to variable temperatures and are strongly coupled to each other and their environment [3, 4].  Quantum thermodynamics is a new field where thermodynamics is studied in the limit where a fully quantum mechanical description is necessary, and seeks to extend the applicability of well-known concepts such as ‘work’ and ‘heat’ beyond classical physics [5]. The aim of this project is to quantify the importance of quantum mechanical and strong coupling effects as the size of a spin grain is reduced.

You will start with a simple quantum mechanical model of coupled spins, applying analytical as well as numerical techniques to solve for the motion of the spins under the application of an external magnetic field and an external source of heat. This will allow the quantification of the degree to which quantum mechanics and strong coupling effects are important.  You will identify experimental parameter ranges where these effects could be evident and these will be given to experimental groups who may be able to test these predictions.  You will be trained in several techniques in quantum thermodynamics theory and become an expert in assessing if the miniaturisation of devices can lead to qualitatively different behaviour and how this may be controlled/harvested.

[1] “Seagate continues to lead as HAMR advances”   http://blog.seagate.com/business/seagate-continues-to-lead-as-hamr-technology-advances/ (2017)
[2] R. F. L. Evans, W. J. Fan, O. Chureemart, T. A. Ostler, M. O. A. Ellis and R. W. Chantrell, J. Phys. Cond. Mat. 26 103202 (2013).
[3] S. Hilt, S. Shabbir, J. Anders, E. Lutz, Phys. Rev. A 83, 030102 (2011).
[4] H. Miller, J. Anders, Phys. Rev. E 95, 062123 (2017).
[5] S. Vinjanampathy, J. Anders, Contemporary Physics 57, 545 (2016); 
[6] J. Goold, M. Huber, A. Riera, L. del Rio and P. Skrzypczyk, J. Phys. A 49 143001 (2016).

This studentship is part of the Centre of Doctoral Training in Metamaterials. Please see all fully funded opportunities.

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Type / Role:

PhD

Location(s):

South West England