Quantization of spin circular photogalvanic effect in altermagnetic Weyl semimetals
Abstract
We theoretically predict a spin-current analog of the quantized circular photogalvanic effect in Weyl semimetals. This phenomenon is forbidden in antiferromagnets by symmetry but uniquely allowed in altermagnets, highlighting a novel and intrinsic characteristic of altermagnetism. To systematically explore second-order spin current responses, we classify all symmetry-allowed responses based on spin point groups. Furthermore, we provide a comprehensive classification of altermagnetic Weyl semimetals by identifying spin space groups that host symmetry-enforced Weyl points. Utilizing this classification, we construct a symmetry-guided tight-binding model and confirm our predictions. Finally, we identify Weyl crossings in a material candidate via first-principle calculations. Our work unveils a distinctive optical response of altermagnets, paving the way for a new frontier in altermagnetism.
Cite
@article{arxiv.2509.05620,
title = {Quantization of spin circular photogalvanic effect in altermagnetic Weyl semimetals},
author = {Hiroki Yoshida and Jan Priessnitz and Libor Šmejkal and Shuichi Murakami},
journal= {arXiv preprint arXiv:2509.05620},
year = {2026}
}
Comments
6+17 pages, 4+1 figures