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arXiv · 2102.09724

Ideal fully spin-polarized type-II nodal line state in half-metals X2YZ4 (X=K, Cs, Rb, Y=Cr, Cu, Z=Cl, F)

Tingli He·Xiaoming Zhang·Lirong Wang·Ying Liu·Xuefang Dai·Liying Wang·Guodong Liu
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Abstract

Lorentz-violating type-II nodal lines exhibit attracting physical properties and have been hot discussed currently. However, their investigations have been mostly limited in nonmagnetic system because of lacking ideal spin-polarized candidates with clean type-II nodal line states. Here, for the first time, we report the family of X2YZ4 (X=K, Cs, Rb, Y=Cr, Cu, Z=Cl, F) compounds are such ideal candidate materials by using the member of K2CuF4 as an example. We show the material is a ferromagnetic half-metal with weak anisotropy, which host fully spin-polarized conducting electrons. In the conducting spin channel, the band crossing form a pair of type-II nodal lines, protected by mirror symmetry. These type-II nodal lines are different with former proposed examples because they have a 100% spin polarization. In addition, we also show the material can realize switchable topological states, which can be easily controlled by external magnetic field. It is noticed that, the material: i) is stable and can be synthesized in experiments; ii) has clear magnetic structure; and iii) manifests clean type-II nodal line state and clear drumhead surface states. Therefore, the proposed X2YZ4 compounds are expected to be an excellent platform to investigate the novel physical properties of both type-II nodal line states with complete

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Tingli He, Xiaoming Zhang, Lirong Wang, Ying Liu, Xuefang Dai, Liying Wang, Guodong Liu. 2021-02-19. Ideal fully spin-polarized type-II nodal line state in half-metals X2YZ4 (X=K, Cs, Rb, Y=Cr, Cu, Z=Cl, F). https://doi.org/10.1016/j.mtphys.2021.100360

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