Magnetic materials showing topologically nontrivial quantum states with high tunability is an undoubtedly important topic in condensed matter physics and material science. Based on the first-principles electronic structure calculations and subsequent symmetry adapted effective low-energy k.p theory, we show in a noncollinear antiferromagnet (AFM), Mn₃Sn, that the switching of the vector-chirality, κ, is an unconventional route to topological phase transition from a nodal-ring to a Weyl point semimetal. Specifically, we find that the switching of κ via staggered rotation leads to gapping out an elliptic nodal-ring everywhere at the Fermi-level except for a pair of points on the ring. As a consequence, the topological phase transition switches the anomalous Hall conductivity (AHC) from zero to a giant value. Furthermore, we theoretically demonstrate how the controlled manipulation of the chiral AFM order keeping κ unaltered favors unusual rotation of Weyl-points on the ring. In fact, without staggered rotation, this enables us to tune and switch the sign of in-plane components of the AHC by a collective uniform rotations of spins in the AFM unit cell.

具有高可调谐性的拓扑非平凡量子态的磁性材料无疑是凝聚态物理和材料科学中的一个重要课题。基于第一原理电子结构计算和随后采用有效低能kp理论的对称性，我们在非共线反铁磁体 (AFM) Mn 3 Sn 中证明，_矢量手性κ的切换是一种非常规途径从节环到韦尔点半金属的拓扑相变。具体来说，我们发现κ通过staggered进行切换_ _ _旋转会导致费米能级上除了环上的一对点之外的任何地方都出现椭圆节环。因此，拓扑相变将反常霍尔电导率（AHC）从零切换到一个巨大的值。此外，我们从理论上证明了手性 AFM 顺序的受控操作如何保持κ不变有利于环上 Weyl 点的异常旋转。事实上，无需交错旋转，这使我们能够通过 AFM 晶胞中自旋的集体均匀旋转来调整和切换 AHC 平面内分量的符号。