Sub-200 ps spin transfer torque switching in in-plane magnetic tunnel junctions with interface perpendicular anisotropy

Abstract

Abstract Ultrafast spin transfer torque (STT) switching in an in-plane MgO magnetic tunnel junction with 50 nm×150 nm elliptical shape was demonstrated in this paper. Switching speeds as short as 165 ps and 190 ps at 50% and 98% switching probabilities, respectively, were observed without external field assistance in a thermally stable junction with a 101% tunnelling magnetoresistance ratio. The minimum writing energy of P-AP switching for 50% and 98% switching probability are 0.16 pJ and 0.21 pJ, respectively. The observed ultrafast switching is believed to occur because of partially cancelled out-of-plane demagnetizing field in the free layer from interface perpendicular anisotropy between the MgO layer and the Co 20 Fe 60 B 20 layer. High J / J c0 ratio and magnetization nucleation at the edge of free layer, which result from the reduced perpendicular demagnetizing field, are possibly two major factors that contribute to the ultrafast STT switching.