Unraveling In-Gap States Induced by Metallocene Molecules on s-Wave Superconductor

Exploring the interactions between superconducting and magnetic materials uncovers a fascinating array of new physical phenomena, offering exciting possibilities for advancements in spintronics and quantum information technologies [1,2]. Although the use of molecules as magnetic components has demonstrated significant promise in various applications, the extensive and diverse range of properties that the molecular realm offers remains largely untapped and unexplored, presenting an exciting opportunity for future research [2]. The presence of magnetic impurities on superconductors give rise to the formation of Yu-Shiba-Rusinov (YSR) bound states within the density of states, significantly influencing the superconducting properties [3]. Here we investigate the magnetic bound states induced by adsorption of Nickelocene (NiCp₂) and Cobaltocene (CoCp₂) on Pb(001) surface using Scanning Tunneling Microscopy. NiCp₂ and CoCp₂ prefer to form islands on the surface of Pb(001). We examined their YSR states on Pb(001), starting from individual molecules and dimers to larger island structures.