无自旋劈裂带的自旋劈裂器：一种可重构的交替磁纹理

中文摘要 AI 辅助

交替磁自旋劈裂效应可将电场转化为横向纯自旋电流，既无净磁化也无电荷霍尔对应物。在已有的材料中，该功能与晶体固定的自旋劈裂带绑定，后者将极化轴锁定在晶格上。我们发现，受挫蜂窝状磁体的非共面对反螺旋基态通过Q锁定螺旋度镜像g实现交替磁操作，该镜像选择自旋电流的极化并禁止垂直极化；反平移Θ则禁止偶宇称自旋劈裂。因此，能带劈裂与自旋劈裂器响应依赖于不同的对称元素，任一元素单独作用都会使电荷霍尔效应归零——这是其他无自旋轨道非共线路径所不具备的冗余性，仅当两个元素都被移除时才会出现电荷霍尔效应。空穴掺杂后可实现“无自旋劈裂带的自旋劈裂器”，其费米能级处对称性允许的奇宇称残余小于 hopping t的2×10⁻⁷，在无自旋轨道耦合时σ_H^(s_y)=0.082 e²/h，且电荷霍尔响应为零。在可编程光子和电路晶格可实现的32位元胞中，选择三个简并Q取向之一可使极化轴以固定大小和电荷霍尔零值精确旋转120°步长，选择规则保持不变。

英文摘要

The altermagnetic spin-splitter effect converts an electric field into a transverse pure spin current, with no net magnetization and no charge-Hall counterpart. In established materials this function is tied to crystal-fixed spin-split bands that lock the polarization axis to the lattice. We show that the noncoplanar counter-spiral ground state of a frustrated honeycomb magnet instead carries the altermagnetic operation through a $\mathbf Q$-locked helicity mirror $g$. The mirror selects the spin-current polarization and forbids the perpendicular one, while an antitranslation $Θ$ forbids even-parity spin splitting. Band splitting and spin-splitter response therefore rest on different symmetry elements. Either element alone enforces the charge-Hall zero---a redundancy absent from other spin--orbit-free noncollinear routes---and a charge Hall appears only when both elements are removed. Hole doping then realizes a \emph{spin splitter without spin-split bands}---the symmetry-allowed odd-parity residual below $2\times10^{-7}$ of the hopping $t$ at the Fermi level---with $σ_H^{(s_y)}=0.082\,e^2/h$ without spin--orbit coupling and with zero charge Hall response. Selecting among the three degenerate $\mathbf{Q}$ orientations rotates the polarization axis in exact $120^\circ$ steps at fixed magnitude and charge-Hall zero; the selection rules persist in a $32$-site cell accessible to programmable photonic and circuit lattices.

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17 pages, 4 figures