Scanning tunneling microscopy studies of atomic impurities on the non-centrosymmetric superconductor BiPd*

In the non-centrosymmetric superconductor BiPd, electrons are exposed to strong Rashba spin-orbit coupling in the bulk, which can allow for both spin-singlet and spin-triplet pairing channels. Introducing impurities to such a superconductor can generate various types of in-gap states. Bound states around non-magnetic impurities are expected in the presence of triplet pairing, and magnetic impurities give rise to Yu-Shiba-Rusinov states. Moreover, the combination of magnetism, spin-orbit coupling and superconductivity provides the essential ingredients for topological superconductivity. Here we use a dilution refrigerator scanning tunneling microscope to study the nature of the superconductivity in BiPd, whose bulk T_c is 3.8 K. We further explore the in-gap bound states of individual atomic impurities on its surface, and discuss the potential of this system as a new platform for Majorana fermions.