Polar Kerr effect measurements of half-Heusler compound YPtBi

Strong spin-orbit coupling in the half-Heusler compound YPtBi leads to a topologically protected surface state and to unconventional superconductivity in the bulk. It was recently suggested [arXiv:2212.09786] that the surface state in this compound could host a superconducting ground state which breaks time reversal symmetry and is independent from the bulk superconductivity. In my talk, I will show polar Kerr effect and scanning tunneling microscopy measurements in search of this surface superconductivity, its order parameter and its interplay with the bulk superconducting ground state.