Dr Sam Holt - PhD student

University of Warwick

Dr Sam Holt joined the Skyrmion Project in 2017 after completing his undergraduate degree in Physics at the University of Warwick.

Sam’s PhD at the University of Warwick was supervised by Professor Geetha Balakrishnan, during which he synthesised and studied polycrystalline, single crystal, and nanocrystalline skyrmion hosting materials. He was awarded the prize for the best thesis by a Science Faculty student at Warwick in 2021 [1]. Sam published a variety of work including establishing the ground state magnetic properties and the magneto-structural relationships in GaV4S8-ySey [2-5], the interplay between the presence of skyrmions and Zn doping in Cu2OSeO3 [6], and investigations into the magnetism of nanoparticles of Cu2OSeO3 [7]. During his PhD he also started working on computationally simulating experimental magnetic techniques, work which he has carried on in his new position at the University of Southampton.

After graduation, Sam took up a Research Fellowship position in the Skyrmion project in 2021 at the University of Southampton, working with Hans Fangohr. He researchers techniques in computational magnetism including developing the Ubermag micromagnetic simulation software [8, 9]. During his time at Southampton he has developed the Python software package mag2exp [10] which aims to help bridge the gap between computational and experimental magnetism by enabling realistic virtual experiments to be performed on computational magnetic structures.

[1] S. J. R. Holt, Structure and Magnetism of Skyrmion Hosting Materials, Ph.D. Thesis, University of Warwick

[2] S. J. R. Holt et al., Structure and magnetism of the skyrmion hosting family GaV4S8-y Seywith low levels of substitutions between 0 ≤ y ≤ 0.5 and 7.5 ≤ y ≤ 8, Physical Review Materials 4, 114413 (2020).

[3] A. Štefančič, S. J. R. Holt et al., Establishing magneto-structural relationships in the solid solutions of the skyrmion hosting family of materials: in GaV4S8-y Sey, Scientific Reports 10, 16485 (2020).

[4] T. J. Hicken, M. N. Wilson, S. J. R. Holt et al., Phys. Rev. B 105, 134414.(2022).

[5] T. J. Hicken, S. J. R. Holt et al., Magnetism and N\'eel skyrmion dynamics in GaV4S8-ySey, Physical Review Research 2, 032001 (2020).

[6] A. Štefančič, S. H. Moody et al., Origin of skyrmion lattice phase splitting in Zn-substituted Cu2OSeO3, Physical Review Materials 2, 111402 (2018).

[7] S. J. R. Holt et al., Investigations of the size distribution and magnetic properties of nanoparticles of Cu2OSeO3, Materials Research Express 8, 116101 (2021).

[8] M. Beg et al. AIP Adv. 7, 056025 (2017)

[9] M. Beg et al. IEEE Trans. Magn. 58.2 1-5. (2022).

[10] https://github.com/ubermag/mag2exp