Details

Autor(en) / Beteiligte

• Jin, Lei
• Zhang, Xiaoming
• Liu, Ying
• Dai, Xuefang
• Wang, Liying
• Liu, Guodong

Titel

Fully spin-polarized double-Weyl fermions with type-III dispersion in the quasi-one-dimensional materials X2RhF6 (X = K, Rb, Cs)

Ist Teil von

• Physical review. B, 2020-11, Vol.102 (19), p.1

Ort / Verlag

College Park: American Physical Society

Erscheinungsjahr

2020

Quelle

American Physical Society Journals

Beschreibungen/Notizen

• 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 ± 2, 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.