Tunable spin Hall and spin Nernst effects in Dirac line-node semimetals XCuYAs (X=Zr, Hf; Y=Si, Ge)
Journal
Physical Review Materials
Journal Volume
4
Journal Issue
12
Date Issued
2020
Author(s)
Prasad B.B., Guo G.-Y.
Abstract
The quaternary arsenide compounds XCuYAs (X=Zr,Hf; Y=Si,Ge) belong to the vast family of the 1111-type quaternary compounds, which possess outstanding physical properties ranging from p-type transparent semiconductors to high-temperature Fe-based superconductors. In this paper, we study the electronic structure topology, the spin Hall effect (SHE), and the spin Nernst effect (SNE) in these compounds based on density functional theory calculations. First we find that the four considered compounds are Dirac semimetals with the nonsymmorphic symmetry-protected Dirac line nodes along the Brillouin zone boundary A-M and X-R and low density of states near the Fermi level (EF). Second, the intrinsic SHE and SNE in some of these considered compounds are found to be large. In particular, the calculated spin Hall conductivity (SHC) of HfCuGeAs is as large as -514(/e)(S/cm). The spin Nernst conductivity (SNC) of HfCuGeAs at room temperature is also large, being -0.73 (/e) (A/m K). Moreover, both the magnitude and sign of the SHC and SNC in these compounds can be manipulated by varying either the applied electric field direction or the spin current direction. The SHE and SNE in these compounds can also be enhanced by tuning the Fermi level via chemical doping or electric gating. Finally, a detailed analysis of the band-decomposed and k-resolved spin Berry curvatures reveals that these large SHC and SNC as well as their notable tunabilities originate largely from the presence of a large number of spin-orbit coupling-gapped Dirac points near the Fermi level as well as the gapless Dirac line nodes, which give rise to large spin Berry curvatures. Our findings thus suggest that the four XCuYAs compounds not only provide a valuable platform for exploring the interplay between SHE, SNE, and band topology, but they also have promising applications in spintronics and spin caloritronics. ? 2020 American Physical Society.
Subjects
Arsenic compounds; Copper compounds; Density functional theory; Electric currents; Electric fields; Electronic structure; Fermi level; Fruits; Germanium compounds; Hafnium compounds; Iron-based Superconductors; Semiconducting germanium; Semiconductor doping; Spin orbit coupling; Topology; Brillouin zone boundary; Chemical doping; Electric gating; Electric-field directions; High temperature; Quaternary compound; Spin hall conductivity; Transparent semiconductor; Spin Hall effect
Type
journal article