Symmetry-protected Dirac nodal lines and large spin Hall effect in $\mathbf{V_6Sb_4}$ with kagome bilayer

TL;DR

This paper investigates V6Sb4, a nonmagnetic kagome metal, revealing symmetry-protected Dirac nodal lines and a significant intrinsic spin Hall effect, highlighting its potential for spintronics applications.

Contribution

The study introduces V6Sb4 as a new kagome metal with simple band topology, demonstrating symmetry-protected Dirac nodal lines and a large intrinsic spin Hall effect through first-principles calculations.

Findings

V6Sb4 hosts symmetry-protected Dirac nodal lines near the Fermi level.

Spin-orbit coupling opens small gaps in the nodal rings.

V6Sb4 exhibits a large intrinsic spin Hall effect due to spin Berry curvature.

Abstract

Recently, a family of nonmagnetic kagome metals \textit{A}$\mathrm{V_3Sb_5}$ (\textit{A}=K, Rb, and Cs) has attracted significant attention for realizing the intertwining of quantum order and nontrivial topology. However, these compounds have been identified to host complex band structures. Therefore, it is desirable to design and synthesize novel kagome materials with a simple band topology and good transport properties. In this study, using first-principles calculations, we present the electronic properties and the intrinsic spin Hall effect of V$_6$Sb$_4$, the latest experimentally synthesized vanadium-based compounds with a kagome bilayer. In the absence of spin-orbital coupling (SOC), this compound is a Dirac nodal line semimetal with symmetry-protected nodal rings near the Fermi level. Within the SOC, the spin-rotation symmetry breaks the gaps of the nodal rings with a small band gap. Furthermore, based on the Wannier tight-binding approach and the Kubo formula, we propose a large spin Hall effect in V$_6$Sb$_4$, which intrinsically originates from the spin Berry curvature. Our work further expands nonmagnetic kagome compounds for applications in spintronics accompanied by exotic quantum order.