Tunneling study of amorphous GdAl 2 films

Abstract

Tunneling measurements on amorphous GdAl 2 films at 4.2 K are presented. A zero-bias anomaly — the giant peak in the tunneling resistance dV dI — is observed. It is found that the anomaly can be accounted for by recent theories which take into consideration the Coulomb interaction of electrons in a disordered material. A slope change of dI dV at low bias is explained in terms of tunneling to inhomogenous material. The dimension of inhomogeneity, 30Å, is of order of ferromagnetic cluster dimension found in a-GdAl 2 by different techniques.