Superconductivity and strong spin-orbit coupling in a new noncentrosymmetric compound ThIrP

• DOI: 10.1007/s11433-021-1731-3
• Publication Date: 2021-09-09T07:03:19Z
• Authors: GuoRui Xiao; QinQing Zhu; YanWei Cui; WuZhang Yang; BaiZhuo Li; SiQi Wu; Guang-Han Cao; Zhi Ren
• Keywords: Tetragonal crystal system; Point reflection; Spin–orbit interaction; Lattice (music)

A new noncentrosymmetric phosphide ThIrP has been synthesized and characterized.X-ray diffraction analysis shows that this compound crystallizes in a LaPtSi-type tetragonal lattice (space group $I$4$_{1}$$md$, $Z$ = 4), whose lattice parameters are $a$ = $b$ = 4.0676(1) A $c$ = 14.3354(2) A and $V$ = 237.191(8) A$^{3}$.Moreover, ThIrP is discovered to be an intermediately coupled, type-II superconductor with possibly multiple gaps below $T_{\\rm~c}$ = 5.07 K. The upper critical magnetic field, Sommerfield coefficient, and Ginzburg-Laudau parameter are determined based on physical property measurements, which are $B_{\\rm~c2}$ = 0.83 T, $\\gamma$ = 7.5 mJ mol$^{-1}$ K$^{-2}$, and $\\kappa_{\\mathrm{GL}}$ = 7.5, respectively.The electronic band structure calculations point out nearly equal contributions of Ir and Th atoms on the density of states around the Fermi surface. In addition, the spin-orbit coupling induced band splitting reaches as large as 270 meV along the $\\Gamma$-$Z$ line. Our results suggest that ThIrP provides a platform to study the interplay between inversion-symmetry breaking, strong spin-orbit coupling, and superconductivity.