Hot-spot mediated current-induced resistance change in magnetic tunnel junctions

Experimental results on the current-induced resistance change in low-resistance (10-60 Ω·μm²) magnetic tunnel junctions with AlO_x barriers are presented. The observed current-induced resistance change remains unaltered even when the ferromagnetic electrodes are saturated by an external field of 8.5 kOe and, therefore, is not related to the relative magnetization configuration of both electrodes. The critical switching current increases with decreasing barrier thickness (increasing hot-spot density), as well as with increasing junction area. Repeated switching (4000 pulses) leads to junction resistance decrease by 3%-4% and a decrease of the relative current-induced resistance change of about 20%, indicating an increase of hot spots or pinhole density upon current stressing. Critical current increases as current pulsewidth decreases.