Topological semimetals host electronic structures with several band-contact points or lines and are generally expected to exhibit strong topological responses. Up to now, most work has been limited to non-magnetic materials and the interplay between topology and magnetism in this class of quantum materials has been largely unexplored. Here we utilize theoretical calculations, magnetotransport and angle-resolved photoemission spectroscopy to propose Fe₃GeTe₂, a van der Waals material, as a candidate ferromagnetic (FM) nodal line semimetal. We find that the spin degree of freedom is fully quenched by the large FM polarization, but the line degeneracy is protected by crystalline symmetries that connect two orbitals in adjacent layers. This orbital-driven nodal line is tunable by spin orientation due to spin–orbit coupling and produces a large Berry curvature, which leads to a large anomalous Hall current, angle and factor. These results demonstrate that FM topological semimetals hold significant potential for spin- and orbital-dependent electronic functionalities.

拓扑半金属的电子结构具有多个带状接触点或带状接触点，通常被期望表现出强大的拓扑响应。迄今为止，大多数工作仅限于非磁性材料，并且在这类量子材料中拓扑和磁性之间的相互作用还没有得到充分的探索。在这里，我们利用理论计算，磁输运和角度分辨光发射光谱法提出了Fe ₃ GeTe _2。，范德华斯材料，作为候选铁磁（FM）节点线半金属。我们发现，大的FM极化完全消除了自旋自由度，但是线的简并性受到连接相邻层中两个轨道的晶体对称性的保护。由于自旋-轨道耦合，该轨道驱动的节点线可通过自旋定向进行调谐，并产生大的贝里曲率，从而导致大的霍尔电流，角度和因数异常。这些结果表明，FM拓扑半金属具有依赖自旋和轨道的电子功能的巨大潜力。