Interfacial microstructure of Fe/AlO_x/Fe magnetic tunnel junctions in high resolution

摘要

Magnetic tunnel junctions were prepared by deposition of a Ta-buffered Fe-AlO_x-Fe trilayer on a thermally oxidized silicon wafer. In order to investigate the influence of different Fe oxides like a spinel-like phase and a spinel (Hycernite) on the tunneling magnetoresistance effect, a ~(57)Fe tracer was deposited at the lower barrier interface. Using conversion electron Mossbauer spectroscopy the evolution of chemical, structural, and magnetic changes in the tracer was monitored starting from the as-prepared state and after several annealing steps. The nuclear probe technique enables to resolve phase formation at the interface with submonolayer resolution.