Point contact spectroscopy on A15 Ti₃Ir

Quantum materials with A15 structure have recently gained renewed interest as they host topological electronic band structures characterized by symmetry-protected multi-degenerate band crossings. These have been predicted to induce a large spin Hall conductivity. In addition, the A15 comprise families of well-known superconducting materials. Phase-pure high-quality single-crystal samples of A15 Ti₃Ir were grown using self-flux method. These samples display a sharp superconducting transition at T_c = 4.5 K. Furthermore, transport and the thermodynamic measurements reveal an additional phase transition around T* = 90 K. We have performed point contact spectroscopy experiments in the normal and superconducting states of Ti₃Ir. In addition to the superconducting gap, we measured another spectral gap structure that evolves systematically with temperature and closes at T*. From detailed analysis of our data we conclude that the transition at T* is associated with significant changes of the Fermi surface consistent with the formation of a charge density wave.