Asymmetric Scattering-Induced Neel Spin-Orbit Torque in Antiferromagnets
TLDR
This paper reveals that asymmetric impurity scattering provides a new band-geometry-driven mechanism for Neel Spin-Orbit Torque in antiferromagnets.
Key contributions
- Introduces asymmetric impurity scattering as a new source of PT-odd spin polarization in antiferromagnets.
- Demonstrates this extrinsic contribution stems from antisymmetric scattering and band geometry.
- Shows this "anomalous skew-scattering" can rival or surpass conventional NSOT mechanisms.
- Establishes a novel band-geometry-driven mechanism for electrical control of antiferromagnets.
Why it matters
This research unveils a previously unrecognized mechanism for Neel Spin-Orbit Torque, crucial for magnetic switching in antiferromagnets. By leveraging asymmetric scattering and band geometry, it offers a more efficient way to electrically control these materials. This advancement has significant implications for future spintronic devices.
Original Abstract
Magnetic switching in antiferromagnets relies on Neel spin orbit torque (NSOT), which originates from a current-induced staggered spin polarization of itinerant electrons. In collinear antiferromagnets, such a response requires the spin susceptibility to be odd under combined space-time inversion symmetry (PT), and is conventionally attributed to symmetric scattering processes. Here, we demonstrate that asymmetric impurity scattering generates an additional PT-odd spin polarization when coupled with the anomalous spin polarizability (ASP) of Bloch electrons. This extrinsic contribution arises from the interplay between antisymmetric higher-order scattering processes and band geometry, effectively converting an otherwise PT-even susceptibility into a staggered spin polarization. Using a minimal model of tetragonal CuMnAs, we show that this anomalous skew-scattering contribution can be comparable to, and with sufficient impurity density even exceed, the conventional symmetric scattering (Drude) contribution. Our results identify a new band-geometry-driven mechanism for NSOT and establish an efficient route for electrical control of antiferromagnets.
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