AI 中文总结
本文建立适用于自旋轨道耦合可忽略的周期性驱动共线磁体的Floquet自旋群框架，可系统确定自旋劈裂的对称性特征，还发现三维体系的高阶自旋劈裂，为光控自旋结构设计提供原理。
AI 中文摘要
异自旋磁体（Altermagnets）兼具动量依赖的自旋劈裂与净磁化消失的特性，为自旋电子学开辟了新机遇。近期研究表明，线偏振光、圆偏振光及多色光场的周期性驱动，可调控异自旋磁体与传统反铁磁体的自旋劈裂，甚至能产生平衡态下不存在的自旋劈裂图案。尽管取得了这些进展，但将光的动力学对称性与自旋劈裂能带对称性关联起来的统一原理仍未建立，这限制了光诱导自旋结构的系统设计。本文通过结合晶体的自旋群与光的动力学群，建立了适用于自旋轨道耦合可忽略的周期性驱动共线磁体的统一Floquet自旋群框架。该框架可系统确定不同驱动方案下自旋劈裂的允许宇称、动量依赖及节点结构。基于该对称性分类，我们表明通过调控驱动场，可在同一材料中切换奇宇称、偶宇称及混合宇称的自旋劈裂；进一步在三维体系中发现了高阶h波与k波自旋劈裂。本研究为光控自旋劈裂建立了统一的对称性框架，为异自旋磁体及相关磁性材料中非平衡自旋能带结构的设计提供了通用原理。
英文摘要
Altermagnets combine momentum-dependent spin splitting with vanishing net magnetization, opening new opportunities for spintronics. Recent studies have shown that periodic driving by linearly or circularly polarized light, as well as by multicolor light fields, can control spin splitting in altermagnets and conventional antiferromagnets, and can even generate spin splitting patterns absent in equilibrium. Despite this progress, a unified principle connecting the dynamical symmetry of light to the symmetry of spin-split bands remains lacking, limiting the systematic design of light-induced spin structures. Here, by combining the spin group of crystals with the dynamical group of light, we establish a unified Floquet spin group framework for the study of periodically driven collinear magnets with negligible spin-orbit coupling. This framework systematically determines the allowed parity, momentum dependence, and nodal structure of spin splitting under different driving protocols. Guided by this symmetry classification, we show that odd-parity, even-parity, and mixed-parity spin splittings can be switched within the same material by tailoring the driving field. We further uncover higher-order $h$-wave and $k$-wave spin splittings in three-dimensional systems. Our work establishes a unified symmetry framework for light-controlled spin splitting and provides general principles for engineering nonequilibrium spin-band structures in altermagnets and related magnetic materials.
Comments8 pages, 3 figures
