Field-free platform for Majorana modes in superconductors

Superconducting materials exhibiting topological properties are emerging as an exciting platform to realize fundamentally new excitations from topological quantum states of matter. Finding a systematic and controllable path to generate nonabelian Majorana zero energy excitations has been the central task in this research direction. Here, we explore the possibility of a field-free platform by depositing magnetic impurities on the surface of candidate topological superconductors. We use scanning tunnelling microscopy to probe localised states induced at the Fe atoms on the atomic scale at sub Kelvin temperatures and find that each Fe adatom generates a striking zero-energy bound state inside the superconducting gap. Our findings point to magnetic adatoms evaporated on bulk superconductors with topological surface states as a new platform for exploring Majorana zero modes under field-free conditions.