交替磁体Ti$_2$XX'单层中的轨道选择自旋分裂
Orbital-Selective Spin Splitting in the Altermagnetic Ti$_2$XX' Monolayers
AI总结：
本文研究单层交替磁体Ti₂XX'的电子特性，发现其价带存在自旋分裂、部分组分费米能级附近导带近自旋简并，源于轨道相关超交换作用，调控费米能级可实现电子态转变，具信息存储应用潜力。
AI中文摘要：
交替磁体近年来受到广泛关注，因其兼具反铁磁体的零净磁矩与铁磁体的动量空间自旋分裂特性。本文系统研究单层交替磁体Ti$_2$XX'（X/X'=F、Cl、Br、I）材料的新奇电子特性，具体而言，所有研究材料的价带均存在自旋分裂，而部分组分在费米能级附近呈现近自旋简并导带，这与常规交替磁体显著不同。该现象可归因于d$_{xz}$或d$_{yz}$轨道中键角敏感的超交换作用，而d$_{x^2-y^2}$轨道的超交换作用对Ti-X-Ti键角不敏感。受此有趣现象启发，通过掺杂或异质结构构建调节费米能级，可实现两种电子态间的转变，赋予这些材料在信息存储器件中的巨大应用潜力。
英文摘要：
Altermagnets have attracted intensive attention recently, owing to their unique combination of zero net magnetic moment of antiferromagnets and momentum space spin-splitting of ferromagnets. Herein, we systematically explore monolayer altermagnetic Ti$_2$XX' (X/X' = F, Cl, Br, I) materials for novel electronic properties. Especifically, spin-splitting exists in the valence bands of all studied materials, whereas several compositions exhibit nearly spin-degenerate conduction bands near the Fermi level, which is markedly different from conventional altermagnets. This phenomenon can be attributed to the bond-angle-sensitive super-exchange occurring in the $d_{xz}$ or $d_{yz}$ orbitals, while the super-exchange of the $d_{x^2-y^2}$ orbital is not sensitive to the Ti-X-Ti bond angle. Motivated by this intriguing phenomenon, Fermi level modulation via doping or heterostructure construction enables the transition between two electronic states, endowing these materials great application potential in information storage devices.
