Composite Spin Hall Conductivity from Non-Collinear Antiferromagnetic Order

Steve Novakov; Peter B Meisenheimer; Grace A Pan; Patrick Kezer; Nguyen M Vu; Alexander J Grutter; Ryan F Need; Julia A Mundy; John T Heron

doi:10.1002/adma.202209866

Composite Spin Hall Conductivity from Non-Collinear Antiferromagnetic Order

Adv Mater. 2023 Aug;35(31):e2209866. doi: 10.1002/adma.202209866. Epub 2023 Jun 28.

Authors

Steve Novakov¹, Peter B Meisenheimer², Grace A Pan³, Patrick Kezer⁴, Nguyen M Vu², Alexander J Grutter⁵, Ryan F Need^{5

6}, Julia A Mundy³, John T Heron²

Affiliations

¹ Department of Physics, University of Michigan, Ann Arbor, MI, 48109, USA.
² Department of Material Science and Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.
³ Department of Physics, Harvard University, Cambridge, MA, 02138, USA.
⁴ Department of Electrical and Computer Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.
⁵ NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899-6102, USA.
⁶ Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA.

PMID: 37120799
DOI: 10.1002/adma.202209866

Abstract

Non-collinear antiferromagnets (AFMs) are an exciting new platform for studying intrinsic spin Hall effects (SHEs), phenomena that arise from the materials' band structure, Berry phase curvature, and linear response to an external electric field. In contrast to conventional SHE materials, symmetry analysis of non-collinear antiferromagnets does not forbid non-zero longitudinal and out-of-plane spin currents with $\hat{x}, \hat{z}$ polarization and predicts an anisotropy with current orientation to the magnetic lattice. Here, multi-component out-of-plane spin Hall conductivities $σ_{xz}^{x},$ $σ_{xz}^{y}, σ_{xz}^{z}$ are reported in L1₂ -ordered antiferromagnetic PtMn₃ thin films that are uniquely generated in the non-collinear state. The maximum spin torque efficiencies (ξ = J_S /J_e ≈ 0.3) are significantly larger than in Pt (ξ ≈ 0.1). Additionally, the spin Hall conductivities in the non-collinear state exhibit the predicted orientation-dependent anisotropy, opening the possibility for new devices with selectable spin polarization. This work demonstrates symmetry control through the magnetic lattice as a pathway to tailored functionality in magnetoelectronic systems.

Keywords: antiferromagnets; low symmetry; spin Hall effect; spin torques; thin films.

Abstract

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