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arXiv · 2510.10309

Roles of Electron-Magnon Cross Diffusion in Unidirectional Magnetoresistance of Metallic Magnetic Bilayers

Shashank Gupta·Steven S. -L. Zhang
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Abstract

Unidirectional magnetoresistance (UMR) in metallic bilayers arises from nonlinear spin-charge transport mediated by broken time-reversal and inversion symmetries, yet the role of magnons remains unsettled. We develop a theoretical framework that incorporates coupled electron-magnon dynamics, revealing cross diffusion and spin-angular-momentum transfer between the two subsystems, which renormalize the characteristic electron and magnon spin-diffusion lengths. We show that nonequilibrium magnons, indirectly excited by the electric field, can suppress UMR by absorbing spin angular momentum from conduction electrons. We also analyze the magnetic-field, thickness, and temperature dependencies and identify distinct features that constitute experimental fingerprints of magnonic contributions to UMR in metallic bilayers, providing qualitative to semiquantitative guidance for elucidating the underlying physical mechanisms.

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Shashank Gupta, Steven S. -L. Zhang. 2025-10-11. Roles of Electron-Magnon Cross Diffusion in Unidirectional Magnetoresistance of Metallic Magnetic Bilayers. https://doi.org/10.1103/pnl1-7vcl

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