Energy-efficient spin-transfer torque magnetization reversal in sub-10-nm magnetic tunneling junction point contacts

Abstract

Spin-transfer torque (STT) magnetization reversal in a magnetic tunneling junction (MTJ), Ta/CoFeB/MgO/CoFeB/Ta, built on the tip of a nanoprobe in a direct contact with a copper substrate is demonstrated in the previously unexplored sub-10-nm diameter range. With the contact resistance of the order of 185 kOhm, the measured magnetoresistance value was 29 %. The average STT reversal current of 95 nA indicated a switching current density of approximately 0.1 MAcm−2 which is more than 30 times smaller than the smallest value reported for STT-MTJs of larger dimensions. An atomistic-scale theory confirmed the experimental result which indicates at least an order of magnitude reduction of the spin damping in the sub-10-nm diameter range.