Magnetic and noncentrosymmetric Weyl fermion semimetals in the R AlGe family of compounds (R =rare earth )

By G. Chang, Bahadur Singh, Su-Yang Xu, G. Bian, Shin-Ming Huang, Chuanghan Hsu, I. Belopolski, N. Alidoust, D. Sanchez, Hao Zheng and 11 more. 2016

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Weyl semimetals are novel topological conductors that host Weyl fermions as emergent quasiparticles. In this Rapid Communication, we propose a new type of Weyl semimetal state that breaks both time-reversal symmetry and inversion symmetry in the $R\mathrm{AlGe}$ ($R=\mathrm{rare}\ensuremath{-}\mathrm{earth}$) family. Compared to previous predictions of magnetic Weyl semimetal candidates, the prediction of Weyl nodes in $R\mathrm{AlGe}$ is more robust and less dependent on the details of the magnetism because the Weyl nodes are generated already by the inversion breaking and the ferromagnetism acts as a simple Zeeman coupling that shifts the Weyl nodes in $k$ space. Moreover, $R\mathrm{AlGe}$ offers remarkable tunability, which covers all varieties of Weyl semimetals including type I, type II, inversion breaking, and time-reversal breaking, depending on a suitable choice of the rare-earth elements. Furthermore, the unique noncentrosymmetric and ferromagnetic Weyl semimetal state in $R\mathrm{AlGe}$ enables the generation of spin currents.

Subfields: Atomic and Molecular Physics, and Optics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/2749bb7b77ba288b7d189559068416ec9ac3299e