Year: 2026
Type: preprint
Abstract: Altermagnets are rapidly emerging as a highly promising platform for spintronics, yet dynamically controlling their spin responses remains a fundamental challenge. In this work, we demonstrate that introducing periodic optical driving and non-Hermiticity provides a powerful route to achieve tunable control over these systems. We derive a general analytical expression for nonlinear spin currents in non-Hermitian phases with a spectral line gap, revealing that the intrinsic response cleanly separates into quantum metric, Berry curvature, and Berry connection dipole contributions. Applying this formalism to a Floquet non-Hermitian $d$-wave altermagnet, we uncover that the nonlinear spin conductivity is overwhelmingly dominated by the bare quantum metric. Furthermore, we show that the optical field's polarization can actively tune -- and even strictly reverse -- the direction of both longitudinal and transverse spin currents. Our work establishes a quantum geometric framework for the optical manipulation of nonlinear spin transport in advanced magnetic materials.
Source: arXiv (Cornell University)
Authors: Chen, Kai, Zhu, Jie
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7161551528
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