2020/09/16 by Lei Jin, Xiaoming Zhang, Ying Liu +3 · 27 citations
Materials Science · Physics and Astronomy · #2D Materials and Applications #Band gap #Condensed matter physics #Degenerate energy levels #Fermion #Graphene research and applications #Mathematical physics #Physics #Quantum mechanics #Semimetal #Spin (aerodynamics) #Topological Materials and Phenomena #Weyl semimetal #cond-mat.mtrl-sci #physics.chem-ph
paper · pdf · doi:10.1103/physrevb.102.195104
published in Physical review. B./Physical review. B 102(19) (American Physical Society) · 8 pages,5 figures
arxiv created 2020/09/16 · openalex created_date 2020/09/21 · openalex publication_date 2020/11/03 · arxiv updated 2020/11/30 · openalex updated_date 2026/08/05
Double-Weyl fermions, as novel topological states of matter, have been mostly discussed in nonmagnetic materials. Here, based on density-functional theory and symmetry analysis, we propose the realization of fully spin-polarized double-Weyl fermions in a family ferromagnetic materials X2RhF6 (X=K, Rb, Cs). These materials have the half-metal ground states, where only the bands from the spin-down channel present near the Fermi energy. The spin-down bands form a pair of triply degenerate nodal points (TDNPs) if spin-orbit coupling (SOC) is not included. Under SOC, one TDNP splits into two double-Weyl points featuring quadratic dispersion along two momentum directions with the chiral charge of \ifmmode±\else\textpm\fi2, and they are protected by the three-fold rotation (C3) symmetry. Unlike most double-Weyl semimetals, the Weyl points proposed here have the type-III dispersion with one of the crossing bands being saddle-shaped. An effective model is constructed, which describes well the nature of the Weyl points. These Weyl points are fully spin-polarized, and are characterized with double Fermi arcs on the surface spectrum. Breaking C3 symmetry by lattice strain could shift one double-Weyl point into a pair of type-II single-Weyl points. The X2RhF6 materials proposed here are excellent candidates to investigate the novel properties of type-III double-Weyl fermions in ferromagnetic system, as well as generate potential applications in spintronics.