Electron transport properties in magnetic tunnel junctions with epitaxial NiFe (111) ferromagnetic bottom electrodes

By employing epitaxial NiFe (111) films as ferromagnetic bottom electrodes, magnetic tunnel junctions with layer sequence of Si (111)/epitaxial Ag/epitaxial Cu/epitaxial NiFe/Al-oxide/CoFe/IrMn/NiFe/Ta were prepared. High tunneling magnetoresistance (TMR) ratios were obtained and the bias dependence of TMR was remarkably reduced. The reason for the small bias dependence of TMR was explained by inelastic electron tunneling spectroscopy. It was clearly elucidated that a well-defined sharp interface formed between the tunnel barrier and the ferromagnetic electrode that is nearly free of crystalline defects. This magnetic tunnel junction has a large capability in engineering aspects if we can reduce the barrier thickness further by decreasing the interface roughness.