Topological transition from nodal to nodeless Zeeman splitting in altermagnets
Topological transition from nodal to nodeless Zeeman splitting in altermagnets
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DOI：
10.1103/physrevb.109.024404
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发表时间：
2023-07
影响因子：
3.7
通讯作者：
R. Fernandes;Vanuildo S. de Carvalho;T. Birol;R. Pereira
中科院分区：
文献类型：
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作者：
R. Fernandes;Vanuildo S. de Carvalho;T. Birol;R. Pereira
在交流磁铁中，将磁矩翻转的配置联系起来的对称性是旋转。这使得它在性质上不同于铁磁体，在铁磁体中不存在这种对称性，或者是共线反铁磁体，这种对称性是晶格平移。在本文中，我们调查的结晶环境，使自旋轨道耦合，对交流磁铁的磁性和电子性质的影响。我们发现，因为每个组件的磁化强度获得自己的角度依赖性，塞曼分裂的频带上的镜像平面的晶体上驻留的具有保护的节线。在穿过费米面时，这些节线会产生夹点，表现为单或双II型外尔节点。我们表明，外部磁场垂直于这些镜像平面只能移动的节线，这样一个临界场值是必要的崩溃的节点，使外尔捏点湮灭。这揭示了从带的节点到无节点塞曼分裂的过渡的拓扑性质。我们还对存在自旋轨道耦合的常见晶体学点群的变磁状态进行了分类，揭示了一个广泛的磁性正交钙钛矿家族可以实现变磁。
In an altermagnet, the symmetry that relates configurations with flipped magnetic moments is a rotation. This makes it qualitatively different from a ferromagnet, where no such symmetry exists, or a collinear antiferromagnet, where this symmetry is a lattice translation. In this paper, we investigate the impact of the crystalline environment, enabled by the spin-orbit coupling, on the magnetic and electronic properties of an altermagnet. We find that, because each component of the magnetization acquires its own angular dependence, the Zeeman splitting of the bands has symmetry-protected nodal lines residing on mirror planes of the crystal. Upon crossing the Fermi surface, these nodal lines give rise to pinch points that behave as single or double type-II Weyl nodes. We show that an external magnetic field perpendicular to these mirror planes can only move the nodal lines, such that a critical field value is necessary to collapse the nodes and make the Weyl pinch points annihilate. This unveils the topological nature of the transition from a nodal to a nodeless Zeeman splitting of the bands. We also classify the altermagnetic states of common crystallographic point groups in the presence of spin-orbit coupling, revealing that a broad family of magnetic orthorhombic perovskites can realize altermagnetism.