PreprintCC BY 4.0arXiv
Quantum-Geometric Subgap Second-Harmonic Generation in PT-Symmetric Antiferromagnetic Insulators
Abstract
Although quantum geometry plays an established role in electronic transport and optical responses, the contribution of the time-reversal-odd Riemannian connection to fully subgap responses remains less explored. Here we identify intrinsic second-harmonic generation in PT-symmetric antiferromagnets, predominantly governed by the real sector of the interband Hermitian connection and arising entirely from virtual interband transitions. In bilayer MnBi2Te4, the response persists in trivial phases but is enhanced in the layer-Chern phase and reverses sign with Néel order, offering a probe of quantum geometry and phase-sensitive readout of antiferromagnetic order without mobile carriers or real excitations.
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BibTeX
@misc{ahmad2026quantumgeometric,
title = {{Quantum-Geometric Subgap Second-Harmonic Generation in PT-Symmetric Antiferromagnetic Insulators}},
author = {Shakeel Ahmad and Fei Xue},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.41167},
eprint = {2610.41167},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.41167},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Quantum-Geometric Subgap Second-Harmonic Generation in PT-Symmetric Antiferromagnetic Insulators
AU - Shakeel Ahmad
AU - Fei Xue
PY - 2026
DA - 2026/10/30
PB - arXiv
DO - 10.48550/arxiv.2610.41167
UR - https://arxiv.org/abs/2610.41167
AB - Although quantum geometry plays an established role in electronic transport and optical responses, the contribution of the time-reversal-odd Riemannian connection to fully subgap responses remains less explored. Here we identify intrinsic second-harmonic generation in PT-symmetric antiferromagnets, predominantly governed by the real sector of the interband Hermitian connection and arising entirely from virtual interband transitions. In bilayer MnBi_2Te_4, the response persists in trivial phases but is enhanced in the layer-Chern phase and reverses sign with Néel order, offering a probe of quantum geometry and phase-sensitive readout of antiferromagnetic order without mobile carriers or real excitations.
ER -