Impact of current paths on measurement of tunneling magnetoresistance and spin torque critical current densities in GaMnAs-based magnetic tunnel junctions

摘要

GaMnAs-based magnetic tunnel junction (MTJ) devices are characterized byin-plane and perpendicular-toplane magnetotransport at low temperatures.Perpendicular-to-plane transport reveals the typical tunneling magnetotransport(TMR) signal. Interestingly, a similar TMR signature is observed in thein-plane transport signal. Here, low-ohmic shunting of the MTJ by the topcontact results in significant perpendicular-to-plane current paths. Thiseffect allows the determination of TMR ratios of MTJs based on a simplifiedin-plane measurement. However, the same effect can lead to an inaccuratedetermination of resistance area products and spin torque critical currentdensities from perpendicular-to-plane magnetotransport experiments on MTJpillar structures.