Zero-bias anomaly in junctions

Center for Materials Research and Analysis and Department of Physics and Astronomy Behlen Laboratory of Physics, University of Nebraska - Lincoln, NE 68588-0111, USA

Received: 12 October 2001
Accepted: 5 February 2002

Abstract

thin films, with crystallites of several microns size, provide the opportunity for the investigation of the intergrain tunneling between a few crystals separated by a 1–2 thick film. A pronounced zero-bias anomaly of the conductance is found at low temperatures. Combined photoemission and inverse photoemission temperature-dependent studies confirm the occurrence of Coulomb blockade. For the strong-tunneling case (), the magnetoresistance decreases strongly with bias. For the weak-tunneling case (), the magnetoresistance decreases by a factor two with increasing bias, as predicted by a co-tunneling model.