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Towards the Next Generation of Spintronics: Transport in Van der Waals Antiferromagnets

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If you have a question about this talk, please contact Dr Sun-Woo Kim.

Antiferromagnetic spintronics is an emerging field that capitalizes on the unique properties of antiferromagnetic materials for spin-based information processing and storage, presenting several advantages over their ferromagnetic counterparts. These include faster spin dynamics, reduced susceptibility to external magnetic fields, and the absence of stray fields that interfere with adjacent devices.

In this talk, I will unveil our theoretical investigations on the development of antiferromagnetic devices, merging distinct yet interconnected explorations. Our journey commences with the concept of van der Waals (vdW) field-free spin-orbital torque (SOT) antiferromagnetic memory. Here, we utilize a vdW bilayer LaBr2, an antiferromagnet with perpendicular magnetic anisotropy, coupled with a monolayer Td phase WTe2, a Weyl semimetal with broken inversion symmetry.[1] This combination heralds devices with a strikingly low critical current density of approximately 10 MA/cm2 and swift field-free magnetization switching in 250 ps, contributing to superior write performance with minimal energy consumption. Moreover, the device boasts a significantly low read error rate, highlighted by a high tunnel magnetoresistance (TMR) ratio of up to 4250%.

I then transition to discussing current-driven magnetoresistance in vdW spin-filter antiferromagnetic tunnel junctions using MnBi2Te4. Our insights indicate that the current-voltage (I-V) characteristics and, consequently, the TMR can be effectively manipulated by adjusting the device length and bias voltage. This control is further enhanced by incorporating a boron nitride layer, which selectively suppresses specific spin channels based on the magnetic configurations, leading to a TMR boost with values soaring up to 3690%.

Concurrently, we delve into the enhancement of orbital transport in altermagnetic (spin-splitting band) RuO2. Through these concerted theoretical efforts, we are paving the way for the next generation of high-efficiency, high-performance antiferromagnetic spintronic devices.


[1] Zhang, Lishu, et al. “Van der Waals Spin-Orbit Torque Antiferromagnetic Memory.” arXiv:2310.02805

[2] Zhang, Lishu, et al. “Current-driven magnetic resistance in van der Waals spin-filter antiferromagnetic tunnel junctions with MnBi2Te4” Physical Review Applied 20 (4), 044056

This talk is part of the Lennard-Jones Centre series.

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