Spinorbit coupling (SOC) is a fundamental interaction in solids that can induce unusual physical properties, from topologically non-trivial insulating states to unconventional pairing in superconductors. SOC also leads to several interesting physical phenomena such as Majorana fermions. TrTX (Tr = Ti, Zr, Hf, T = transition metals; X = P, As, Si) are known as a group of superconductors with a relatively high Tc = 15 K for MoRuP. We will focus on the Ir-compounds, which have strong SOC, arising from 5d-orbitals, to explore unconventional superconductivity. Recently Kase et al, [Super. Sci. Tech. 29 (2016) 035011] discovered a new series of 111 superconductor, TrIrSi with Tc = 1.4 K (Ti), 1.85 K (Zr), and 3.40 K (Hf). We propose to investigate the role of spin orbit coupling in the superconducting state using zero-field and transverse field muSR measurements on the MUSR spectrometer.
