Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session K52: Spin-Orbit Torques and Spin-Torque Oscillators: II
3:00 PM–5:00 PM,
Tuesday, March 15, 2022
Room: McCormick Place W-475A
Sponsoring Units: GMAG DMP FIAP
Chair: Benedetta Flebus, Boston College
Abstract: K52.00001 : Spin-orbit torque switching of metallic antiferromagnets and ferrimagnets
3:00 PM–3:36 PM
Here we present our recent results in SOT control of AFM and FIM order. First, we discuss SOT control of AFM order in two metallic antiferromagnets (PtMn and non-collinear IrMn3) [1, 2]. We show that pillars of both AFMs, grown on a heavy metal (HM) layer, can be reversibly switched between different magnetic states by electric currents. We also present an experimental protocol to unambiguously distinguish current-induced magnetic and nonmagnetic switching signals in AFM/HM structures. A six-terminal double-cross device is constructed, with an IrMn3 pillar placed on one cross. The differential voltage is measured between the two crosses after each switching attempt. For a wide range of current densities, reversible switching is observed only when write currents pass through the cross with the IrMn3 pillar. This eliminates the possibility of non-magnetic switching artifacts, which complicated the interpretation of most previous AFM/HM switching experiments.
Next, we present a strategy for deterministic field-free switching of perpendicular ferrimagnetic films by using chiral symmetry-breaking to eliminate the need for an external magnetic field . Bias-field-free SOT switching is demonstrated in a perpendicular CoTb film with an engineered vertical composition gradient. The vertical structural inversion asymmetry induces strong intrinsic SOTs and a gradient-driven Dzyaloshinskii–Moriya interaction (g-DMI), which dynamically breaks the in-plane symmetry during the switching process. This approach is scalable to large wafer size.
 Nature Elec. 3, 92, (2020)
 Nature Comm. 12, 3828, (2021)
 Nature Comm. 12, 4555, (2021)
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