Large spin-orbit splitting and weakly-anisotropic superconductivity revealed with single-crystalline noncentrosymmetric CaIrSi3

TL;DR

This study investigates the electronic and superconducting properties of CaIrSi3, a noncentrosymmetric compound with strong spin-orbit coupling, revealing nearly isotropic superconductivity despite anisotropic vortex pinning.

Contribution

It provides detailed experimental and theoretical insights into the spin-orbit effects and superconducting anisotropy in CaIrSi3, a Rashba-type noncentrosymmetric superconductor.

Findings

Strong spin-orbit interaction influences electronic states.

Superconductivity is nearly isotropic with 10% anisotropy.

Anisotropic vortex pinning observed despite isotropic superconductivity.

Abstract

We report normal and superconducting properties of the Rashba-type noncentrosymmetric com- pound CaIrSi3, using single crystalline samples with nearly 100% superconducting volume fraction. The electronic density of states revealed by the hard x-ray photoemission spectroscopy can be well explained by the relativistic first-principle band calculation. This indicates that strong spin-orbit interaction indeed affects the electronic states of this compound. The obtained H - T phase diagram exhibits only approximately 10% anisotropy, indicating that the superconducting properties are almost three dimensional. Nevertheless, strongly anisotropic vortex pinning is observed.