Quantum Geometry-Driven Nonlinear Spin Currents in Floquet Non-Hermitian Altermagnets
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arXiv
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| Format: | Preprint |
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2026
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| _version_ | 1866913131907776512 |
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| author | Chen, Kai Zhu, Jie |
| author_facet | Chen, Kai Zhu, Jie |
| contents | 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. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2605_15541 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Quantum Geometry-Driven Nonlinear Spin Currents in Floquet Non-Hermitian Altermagnets Chen, Kai Zhu, Jie Mesoscale and Nanoscale Physics Materials Science 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. |
| title | Quantum Geometry-Driven Nonlinear Spin Currents in Floquet Non-Hermitian Altermagnets |
| topic | Mesoscale and Nanoscale Physics Materials Science |
| url | https://arxiv.org/abs/2605.15541 |