Rarita-Schwinger-Weyl semimetal in Jeff=3/2 electron systems

TL;DR

This paper introduces a novel relativistic semimetal model based on Jeff=3/2 electrons, featuring unique chiral gapless points and surface states, expanding the understanding of topological semimetals.

Contribution

It proposes a new Jeff=3/2 semimetal model with separated chiral gapless points and distinctive surface Fermi arcs, extending topological semimetal concepts to higher spin systems.

Findings

Separated right- and left-handed gapless points in Brillouin zone

Presence of Fermi arc network on certain surfaces

Surface states depend on surface orientation and parity of n1+n2+n3

Abstract

We propose a relativistic Jeff=3/2 semimetal with 4d1 or 5d1 electrons on a cubic lattice when the strong spin-orbital coupling takes over the Hunds' coupling. A relativistic spinor with spin 3/2 is historically called Rarita-Schwinger spinor. In the massless case, the right- and left-handed chiral degrees of freedom of the Rarita-Schwinger spinors are independent. In the lattice model that we propose, the right- and left- handed gapless points in Brillouin zone are separated. We call this linearly dispersed semimetal Rarita-Schwinger-Weyl semimetal, similar to Weyl semimetal for spin 1/2 systems. There is a network of gapless Fermi arcs in the surface Brillouin zone if n1+n2+n3 is even for the normal vector (n1,n2,n3) of the surface while the surface is insulator if n1+n2+n3 is odd.