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Device Materials Group


Supervisor: Prof Jason Robinson

Research area: Superconducting spintronics

My work focuses on thin film magnetism and superconductivity. I use pulsed laser deposition to grow ultra-thin epitaxial single crystal films of complex oxide materials, which I then characterise using x-ray techniques, electrical transport measurements, and magnetometry to study phenomena arising from interfaces.

Much of my PhD has been concerned with the controversial reports of skyrmions in several-unit-cell thick SrRuO3 films. Skyrmions are topologically protected nanometer-scale magnetic whirls which are of great interest for their potential use in future generation computing devices as information carriers. Detection of a topological Hall effect is one of the signature Hallmarks (please pardon the pun) of skyrmions. However I have shown that the apparent topological Hall effect in SrRuOcould instead arise from thickness inhomogeneity and not skyrmions [1].

I have also worked on exchange coupling at magnetic perovskite interfaces, and collaborated in thin film growth and characterisation for unconventional superconducting Sr2RuO4 [2] and magnetic insulating YFe5O12 films [3]. Recently I've been interested in numerical modelling of spin-orbit coupled superconducting films [4], and I'm now working on modelling superconducting junctions.


Key publications: 

[1] G. Kimbell, P. M. Sass, B. Woltjes, E. K. Ko, T. W. Noh, W. Wu, and J. W. A. Robinson, Two-Channel Anomalous Hall Effect in SrRuO3, Phys. Rev. Materials 4, 054414 (2020).

[2] C. M. P. Garcia, A. Di Bernardo, G. Kimbell, M. E. Vickers, F. C.-P. Massabuau, S. Komori, G. Divitini, Y. Yasui, H. G. Lee, J. Kim, B. Kim, M. G. Blamire, A. Vecchione, R. Fittipaldi, Y. Maeno, T. W. Noh, and J. W. A. Robinson, Pair Suppression Caused by Mosaic-Twist Defects in Superconducting Sr 2 RuO 4 Thin-Films Prepared Using Pulsed Laser Deposition, Communications Materials 1, 1 (2020).

[3] Y. Li, M. Amado, T. Hyart, G. P. Mazur, V. Risinggård, T. Wagner, L. McKenzie-Sell, G. Kimbell, J. Wunderlich, J. Linder, and J. W. A. Robinson, Transition between Canted Antiferromagnetic and Spin-Polarized Ferromagnetic Quantum Hall States in Graphene on a Ferrimagnetic Insulator, Phys. Rev. B 101, 241405 (2020).

[4] L. A. B. Olde Olthof, J. R. Weggemans, G. Kimbell, J. W. A. Robinson, and X. Montiel, Tunable Critical Field in Rashba Superconductor Thin Films, Phys. Rev. B 103, L020504 (2021).


 Graham  Kimbell
Not available for consultancy