Modic K A, Meng Tobias, Ronning Filip, Bauer Eric D, Moll Philip J W, Ramshaw B J
Max-Planck-Institute for Chemical Physics of Solids, Dresden, 01187, Germany.
Institut für Theoretische Physik, Technische Universität Dresden, 01062, Dresden, Germany.
Sci Rep. 2019 Feb 14;9(1):2095. doi: 10.1038/s41598-018-38161-7.
We present a high magnetic field study of NbP-a member of the monopnictide Weyl semimetal (WSM) family. While the monoarsenides (NbAs and TaAs) have topologically distinct left and right-handed Weyl fermi surfaces, NbP is argued to be "topologically trivial" due to the fact that all pairs of Weyl nodes are encompassed by a single Fermi surface. We use torque magnetometry to measure the magnetic response of NbP up to 60 tesla and uncover a Berry paramagnetic response, characteristic of the topological Weyl nodes, across the entire field range. At the quantum limit B (≈32 T), τ/B experiences a change in slope when the chemical potential enters the last Landau level. Our calculations confirm that this magnetic response arises from band topology of the Weyl pocket, even though the Fermi surface encompasses both Weyl nodes at zero magnetic field. We also find that the magnetic field pulls the chemical potential to the chiral n = 0 Landau level in the quantum limit, providing a disorder-free way of accessing chiral Weyl fermions in systems that are "not quite" WSMs in zero magnetic field.
我们展示了对单磷化物外尔半金属（WSM）家族成员NbP的高磁场研究。虽然单砷化物（NbAs和TaAs）具有拓扑上不同的左旋和右旋外尔费米面，但NbP被认为是“拓扑平凡的”，因为所有外尔节点对都被单个费米面所包围。我们使用扭矩磁强计测量了高达60特斯拉的NbP的磁响应，并在整个磁场范围内发现了拓扑外尔节点特有的贝里顺磁响应。在量子极限B（≈32 T）下，当化学势进入最后一个朗道能级时，τ/B的斜率会发生变化。我们的计算证实，这种磁响应源于外尔口袋的能带拓扑结构，尽管在零磁场下费米面包含了两个外尔节点。我们还发现，在量子极限下，磁场将化学势拉到手征n = 0的朗道能级，为在零磁场下“不完全”是WSM的系统中获取手征外尔费米子提供了一种无无序的方法。
