Electrical Resistance Mapping of Oxide Ferromagnetic Electrodes and Tunnel Barriers by Conducting Atomic Force Microscopy

Since the discovery of colossal magnetoresistance in manganites, there is a high interest in the fabrication of magnetic tunnel junctions made with all-oxide ferromagnetic electrodes and barrier. (001)-oriented La2/3Ca1/3MnO3 (LCMO) and SrTiO3 (STO) films are the most investigated materials as ferromagnetic electrode and tunnel barrier, respectively. The usefulness of these oxides for the application is well demonstrated, but there is a high reduction of the operation temperature that limits its use. Overcoming the reduction of properties at high temperature is a challenge. The cause of the reduction is not well understood, although electronic segregation at interfaces is likely to be at the origin.