It is commonly believed that the energy bands of typical collinear antiferromagnets (AFs), which have zero net magnetization, are Kramers spin-degenerate. Kramers nondegeneracy is usually associated with a global time-reversal symmetry breaking (e.g., via ferromagnetism) or with a combination of spin–orbit interaction and broken spatial inversion symmetry. Recently, another type of spin splitting was demonstrated to emerge in some collinear magnets that are fully spin compensated by symmetry, nonrelativistic, and not even necessarily noncentrosymmetric. These materials feature nonzero spin density staggered in real space as seen in traditional AFs but also spin splitting in momentum space, generally seen only in ferromagnets. This results in a combination of materials characteristics typical of both ferromagnets and AFs. Here, we discuss this recently discovered class with application to a well-known semiconductor, FeSb₂, and predict that with certain alloying, it becomes magnetic and metallic and features the aforementioned magnetic dualism. The calculated energy bands split antisymmetrically with respect to spin-degenerate nodal surfaces rather than nodal points, as in the case of spin–orbit splitting. The combination of a large (0.2-eV) spin splitting, compensated net magnetization with metallic ground state, and a specific magnetic easy axis generates a large anomalous Hall conductivity (∼150 S/cm) and a sizable magnetooptical Kerr effect, all deemed to be hallmarks of nonzero net magnetization. We identify a large contribution to the anomalous response originating from the spin–orbit interaction gapped anti-Kramers nodal surfaces, a mechanism distinct from the nodal lines and Weyl points in ferromagnets.

通常认为，净磁化为零的典型共线反铁磁体 (AF) 的能带是克莱默自旋简并。克莱默斯非简并性通常与全局时间反演对称性破坏（例如，通过铁磁性）或自旋轨道相互作用和空间反演对称性破坏的组合有关。最近，另一种类型的自旋分裂被证明出现在一些共线磁体中，这些磁体通过对称性、非相对论性、甚至不一定非中心对称来完全自旋补偿。这些材料具有在真实空间交错的非零自旋密度，如在传统 AF 中所见，但在动量空间中也具有自旋分裂，通常仅在铁磁体中可见。这导致了铁磁体和 AF 的典型材料特性的组合。这里，₂，并预测通过一定的合金化，它变成磁性和金属，并具有上述磁性二元性。计算的能带相对于自旋简并节点表面而不是节点点呈反对称分裂，如自旋轨道分裂的情况。大的（0.2-eV）自旋分裂、金属基态的补偿净磁化强度和特定的磁易轴的组合产生了大的反常霍尔电导率（~150 S/cm）和相当大的磁光克尔效应，所有这些都被认为是是非零净磁化强度的标志。我们确定了源自自旋轨道相互作用间隙反克莱默节点表面的异常响应的很大贡献，这是一种不同于铁磁体中的节点线和外尔点的机制。