Temperature Dependence of Electrical Transport and Magnetization Reversal in Magnetic Tunnel Junction

A series of tunneling magnetoresistance (TMR) has been measured at various temperatures ranging from 4 K to 360 K for characterizing the electrical transport and magnetization reversal of nanostructured magnetic tunnel junctions (MTJs) with thin effective MgO barrier of 1 nm thickness and resistance-area (RA) product of 10 Omega mu m(2). MTJs with 150 x 250 nm(2) elliptical shape were fabricated by using electron beam lithography in combination with ion beam milling. Typical TMR curves were observed at temperature above 70 K, below which there was no significant anti-parallel (AP) state revealed. A linear relationship is found between resistance and temperature in both parallel (P) and AP states, having linear coefficients of -4.15 x 10(-4) and -8.07 x 10(-4) (Omega/K), respectively. The TMR ratio was found to be proportional to 1-BT3/2. The negative temperature coefficients and TMR tendency with temperature indicated that electrical transport is dominated mainly by tunneling mechanism. In addition, the biasing field of pinned CoFeB layer due to RKKY coupling increased with decreasing temperature until a maximum biasing field reached at 200 K, after which the biasing field decreased with decreasing temperature.