Type-I/Type-II superconductivity in noncentrosymmetric compound Ir$_2$Ga$_9$

Abstract

We have performed magnetization, specific heat, and muon spin relaxation ($\mu$SR) measurements on single crystals of the noncentrosymmetric superconductor Ir$_{2}$Ga$_{9}$. The isothermal magnetization measurements show that there is a crossover from Type-I to Type-II superconductivity with decreasing temperature. Potential multi-band superconductivity of Ir$_{2}$Ga$_{9}$~is observed in the specific heat data. $\mu$SR~measurement is performed to map the phase diagram of Ir$_{2}$Ga$_{9}$, and both Type-I and Type-II superconductivity characteristics are obtained. Most importantly, a more unique region with the coexistence of Type-I and Type-II $\mu$SR signals is observed. In addition, time reversal symmetry is found to be preserved in Ir$_{2}$Ga$_{9}$ by zero field $\mu$SR measurement.