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Group Seminar 2023/24

Category
Group Seminar
Date
Date
Wednesday 17 January 2024, 14:00-15:00
Location
Electrical Engineering Keysight Technologies LT (1.52)
Speaker
Prof Hidekazu Kurebayashi
Institution
Department of Electronic & Electrical Engineering London Centre for Nanotechnology, UCL
Title
Controlling magnetism and spin transport in van der Waal magnets via carrier doping
Category

Abstract:

Since 2017 when long-range magnetic order has been shown in exfoliated magnetic van der Waals (vdW) systems [1-2], magnetic vdW materials have attracted a great deal of attention due to its unique playground for studying magnetism and spin transport in their exfoliated monolayers/heterostructures. For example, many of them have inherently low crystalline symmetries to support unconventional spin texture in momentum space for current-induced magnetisation switching [3]. It turns out that carrier doping is more effective to vdW systems than to conventional 3D materials, in controlling physical parameters and even in generating new phases of matter.

            In this seminar, I will present our recent work of controlling magnetic properties of Cr2Ge2Te6 (CGT) by electrostatic doping and chemical intercalation. Upon electrn doping, pristine insulating CGT crystals become electrically conductive, allowing us to probe their magnetism by magneto-transport. In both doping cases, we observed substantial enhancement of TC from 65 K (undoped case) to 240 K, together with magnetic easy/hard axis switching [4-5]. We argue that the electron doping activates the (carrier-mediated) double-exchange interaction that is a main cause of the Tc enhancement. Spin-orbit torques have been also analysed in the electrostatically gated CGT and there is some signature of Rashba spin-orbit intereaction, accompanied with a spin-orbit term originating from CGT’s three-fold crystalline symmetry [6]. We successfully generate spin-glass dynamics by chemical intercalation in CGT [5]. Such spin-glass states coexist with a ferromagnetically ordered phase in intercalated CGT, i.e. the reentrant spin-glass states.

References

[1] C. Gong et al., Nature 546, 265 (2017).

[2] B. Huang et al., Nature 546, 270 (2017).

[3] H. Kurebayashi et al., Nat. Rev. Phys. 4, 150 (2022).

[4] I. A. Verzhbitskiy et al., Nat. Electron. 3, 460 (2020).

[5] S. Khan et al., arXiv:2312.17554

[6] I. A. Verzhbitskiy et al., unpublished.