Voltage dependence of the magnetoresistance and the tunneling current in magnetic tunnel junctions (abstract)

Magnetic tunnel junctions (MTJ), structures consisting of two ferromagnetic layers separated by a thin barrier of Al2O3, have recently been shown to exhibit large magnetoresistance (MR) at room temperature. The possible use of these structures in devices requires a thorough characterization and understanding of the transport properties of MTJs, which has motivated the present work. The junctions studied here were fabricated via dc sputtering on silicon substrates at room temperature with a series of contact masks to define the junction area (80×80 μm2), and plasma oxidation to produce the insulating barrier. A long standing problem of MTJs is the sensitivity of their MR to bias voltage. For example, in a recent work1 it was reported that the peak MR of 11% exhibited by a CoFe/Al2O3/Co junction was decreased by half at a bias voltage of