High bias voltage dependence in tunneling magnetoresistance of a ramp-type junction

Abstract

A ramp-type tunneling magnetoresistance (TMR) junction having structure NiO(60 nm)/pinned Co(10 nm)/NiO(60 nm)/barrier Si3N4(2-6 nm)/free NiFe(10 nm) with the 15degrees slope was investigated. We obtained nonlinear I-V characteristics for ramp-type tunneling junctions that are distinctively different with and without an applied magnetic field. In the barrier with a Si3N4 thickness of 4 nm, the bias voltage dependence of TMR was stable up to 10 V with a negative TMR ratio of about -10%. The negative TMR is very peculiar for an asymmetric tunneling process between a wedge Co pinned layer and a free NiFe layer. (C) 2003 American Institute of Physics.