Prediction of crossing nodal-lines and large intrinsic spin Hall conductivity in topological Dirac semimetal Ta3As family

Abstract

Topological insulators (TIs) are considered as ideal platforms for generating large spin Hall conductivity (SHC), however, the bulk carrier problem, which is unavoidable in TIs, hinders their practical applications. Recently, topological semimetals (TSMs) have been proposed to achieve large SHC to replace TIs. However, the ideal TSM candidates with large SHC are still lacking. In terms of first-principles calculations, we predict that Ta3As family compounds exhibit complex crossing nodal-lines (CNL) properties in absence of the spin-orbit coupling (SOC). However, they transfer to Dirac TSMs under the influence of strong SOC, and present large SHC around Fermi level in particular. Remarkably, the SHC value of Ta3Y (Y = As, Sb, Bi) is around 1500–1700 (hbar /e)({mathrm{{Omega}}} cdot {mathrm{cm}})^{ - 1}, which is comparable to noble metal Pt and much larger than TIs, Weyl TSMs, and 4d/5d transition metals. Our work not only suggests a kind of TSM family with interesting Dirac CNL around Fermi level, but also paves the way for searching large intrinsic SHC materials in complex CNL TSM systems.