Abstract

By means of ab initio band structure methods and model Hamiltonians we investigate the electronic, spin and topological properties of four monopnictides crystallizing in bct structure. We show that the Weyl bands around a WP W1 or W2 possess a strong anisotropy and tilt of the accompanying Dirac cones. These effects are larger for W2 nodes than for W1 ones. The node tilts and positions in energy space significantly influence the DOS of single-particle Weyl excitations. The node anisotropies destroy the conventional picture of (anti)parallel spin and wave vector of a Weyl fermion. This also holds for the Berry curvature around a node, while the monopole charges are independent as integrated quantities. The pairing of the nodes strongly modifies the spin texture and the Berry curvature for wave vectors in between the two nodes. Spin components may change their orientation. Integrals over planes perpendicular to the connection line yield finite Zak phases and winding numbers for planes between the two nodes, thereby indicating the topological character.

Graphical abstract

中文翻译：

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Weyl节点的各向异性，倾斜和配对的影响：Weyl半金属TaAs，TaP，NbAs和NbP

摘要

通过从头算带结构方法和模型哈密顿量，我们研究了在bct结构中结晶的四种单肽的电子，自旋和拓扑性质。我们显示，WP W1或W2周围的Weyl带具有强烈的各向异性和伴随的Dirac锥的倾斜。与W1节点相比，W2节点的影响更大。节点的倾斜和能量空间中的位置会显着影响单粒子Weyl激发的DOS。节点各向异性破坏了韦尔费米子的（反）平行自旋和波矢量的传统图像。这也适用于围绕节点的贝里曲率，而单极电荷作为积分量是独立的。节点的配对强烈修改了两个节点之间波矢量的自旋纹理和贝里曲率。旋转组件可能会改变其方向。在垂直于连接线的平面上积分会产生有限的Zak相和两个节点之间平面的绕组数，从而表明拓扑特征。

图形概要