Zeeman splitting of the coulomb anomaly: A tunneling study in two dimensions
We report measurements of the tunneling density of states (DOS) of ultrathin Al films in which superconductivity is quenched by a parallel magnetic field, [Formula presented]. The normal state DOS not only displays the usual logarithmic zero bias anomaly (ZBA) but also a new anomaly, superimposed on the ZBA, that appears at bias voltages [Formula presented], the electron Zeeman splitting. Measurements in tilted fields reveal that the Zeeman feature collapses with increasing perpendicular field component, suggesting that it is associated with the Cooper electron-electron interaction channel. © 1996 The American Physical Society.