Appearance of strong spin-orbit coupling (SOC) is apparent in ternary equiatomic compounds with 5d-electrons due to the large atomic radii of transition metals. SOC plays a significant role in the emergence of unconventional superconductivity. Here we examined the superconducting state of HfIrSi using magnetization, specific heat, zero and transverse-field (ZF/TF) muon spin relaxation/rotation (μSR) measurements. Superconductivity is observed at TC = 3.6 K as revealed by specific heat and magnetization measurements. From the TF−μSR analysis it is clear that superfluid density well described by an isotropic BCS type s-wave gap structure. Furthermore, from TF−μSR data we have also estimated the superconducting carrier density ns = 6.6 ×1026m−3, London penetration depth λL(0) = 259.59 nm and effective mass m∗ = 1.57 me. Our zero-field muon spin relaxation data indicate no clear sign of spontaneous internal field below TC, which implies that the time-reversal symmetry is preserved in HfIrSi. Theoretical investigation suggests Hf and Ir atoms hybridize strongly along the c-axis of the lattice, which is responsible for the strong three-dimensionality of this system which screens the Coulomb interaction. As a result despite the presence of correlated d-electrons in this system, the correlation effect is weakened, promoting electron-phonon coupling to gain importance.
@article{arxiv.1903.09361,
title = {Investigation of Superconducting Gap Structure in HfIrSi using muon spin relaxation/rotation},
author = {A. Bhattacharyya and K. Panda and D. T. Adroja and N. Kase and P. K. Biswas and Surabhi Saha and Tanmoy Das and M. R. Lees and A. D. Hillier},
journal= {arXiv preprint arXiv:1903.09361},
year = {2020}
}