Effect of local density of states on the impurity-induced many-body ground states in superconductivity

Abstract

Magnetic impurities on s-wave superconductors locally break time reversal symmetry and thus provide exchange potential to break Cooper pairs. As a result, impurity-induced bound states appear inside superconducting gap, which is called Yu-Shiba-Rusinov (YSR) bound states. It is well known that the YSR bound states depend on the impurity spin (S), exchange coupling energy (J), and the local density of states (LDOS) at Fermi energy (EF). Theory and experiments have shown that the YSR bound states indeed depend on the exchange coupling energy J. However, experimental evidence of showing their electron densities dependence has been lacking. In this study, we used Ar-induced nano-cavity in Pb(111) substrate to control the LDOS at EF. We systematically discuss the way the YSR bound states respond to the variation of LDOS at EF.