Kramers Dichroism in PT Symmetric Magnets

Abstract:The quantum states in doubly degenerate Kramers pairs can act as an internal degree of freedom. Here we uncover a Kramers dichroism in PT symmetric magnets: interband transitions induced by circularly polarized light irradiation can selectively polarize Kramers partnered states allowing to control the Kramers degree of freedom. In contrast, Kramers pairs optically excited by linearly polarized light remain in a completely mixed state. Strikingly, we find a class of second-order nonlinear responses that directly track the polarization between Kramers partnered states. Such Kramers nonlinearities can be pronounced producing large second-order nonlinear layer polarization responses activated by Kramers degeneracy in layered antiferromagnets. Together with Kramers dichroism, these render optical responses a novel means for accessing the Kramers degree of freedom and diagnosing their quantum state.

Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Quantum Physics (quant-ph)

arXiv:2406.19444 [cond-mat.mes-hall]

(or arXiv:2406.19444v3 [cond-mat.mes-hall] for this version)

https://doi.org/10.48550/arXiv.2406.19444 Focus to learn more arXiv-issued DOI via DataCite

Phys. Rev. Research 8, 033046 (2026)

https://doi.org/10.1103/225j-wnv6 Focus to learn more DOI(s) linking to related resources

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