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MA: Fachverband Magnetismus

MA 35: Spin Transport and Orbitronics, Spin-Hall Effects I (joint session MA/TT)

MA 35.1: Talk

Thursday, March 21, 2024, 09:30–09:45, H 2013

Fluctuation mediated spin-orbit torque enhancement in the noncollinear antiferromagnet Mn3Ni0.35Cu0.65N — Arnab Bose¹, Aga Shahee¹, Tom G. Saunderson¹, •Adithya Rajan¹, Dongwook Go², Aurélien Manchon³, Yuriy Mokrousov^1,2, and Mathias Kläui¹ — ¹Institut für Physik, Johannes-Gutenberg-Universität Mainz, 55099 Mainz, Germany — ²Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich, 52424 Jülich, Germany — ³CINaM, Aix-Marseille Université, CNRS, Marseille, France

Spin fluctuations near magnetic phase transitions play a pivotal role in generating exotic phenomena. This study focuses on experimental investigation of temperature-dependent spin torques in the noncollinear antiferromagnet Mn3Ni0.35Cu0.65N (MNCN). Our findings reveal a significant and nontrivial temperature dependence of spin-orbit torques (SOT), peaking near MNCN's Néel temperature. This behavior cannot be explained by conventional scattering mechanisms of the SHE. Notably, a maximum SOT efficiency of 30 % is measured, surpassing that of commonly studied nonmagnetic materials like Pt. Theoretical calculations support a negligible SHE and a pronounced orbital Hall effect, explaining the observed spin torques. We propose a novel mechanism where fluctuating antiferromagnetic moments induce substantial orbital currents near the Néel temperature. These results provide a promising avenue for enhancing spin torques, with potential applications in magnetic memory.

Keywords: noncollinear antiferromagnet; spin torque; Orbital current