ZEEMAN SPLITTING OF THE COULOMB ANOMALY - A TUNNELING STUDY IN 2 DIMENSIONS

We report measurements of the tunneling density of states (DOS) of ult rathin Al films in which superconductivity is quenched by a parallel m agnetic field, H-parallel to > 48 kG. The normal state DOS not only di splays the usual logarithmic zero bias anomaly (ZBA) but also a new an omaly, superimposed on the ZBA, that appears at bias voltages V simila r to 2 mu(B)H(parallel to)/e, the electron Zeeman splitting. Measureme nts in tilted fields reveal that the Zeeman feature collapses with inc reasing perpendicular field component, suggesting that it is associate d with the Cooper electron-electron interaction channel.