[14p-2J-5~18] 10.2 スピントルク・スピン流・回路・測定技術

▼ [14p-2J-8] Switching characteristics of CoFeB-MgO magnetic tunnel junctions in the ns regime

〇Naoki Ohshima¹, Shuji Kubota¹, Hideo Sato^2,3, Shunsuke Fukami^2,3, Fumihiro Matsukura^1,2,4, Hideo Ohno^1,2,3,4 (1.Laboratory for Nanoelectronics and Spintronics, RIEC, Tohoku Univ., 2.CSIS, Tohoku Univ., 3.CIES, Tohoku Univ., 4.WPI-AIMR, Tohoku Univ.)

キーワード：spintronics,Magnetic tunnel junction

We investigate the spin-transfer torque (STT) switching characteristics in ns regime for CoFeB-MgO magnetic tunnel junctions with perpendicular easy axis (p-MTJs). We evaluate the characteristics for the MTJs with various diameters where pulse duration t_p is varied from 1 to 5 ns. t_p dependence of the switching current I_C increases linearly with t_p^-1 in agreement with the expected dependence from a macrospin model. The STT efficiency is evaluated from the slope of I_C-t_p^-1 by using the magnetization of the corresponding blanket film and the thermal stability factor of devices, and the value is higher than that expected from the tunnel magnetoresistance ratio. This results suggest that one need to go beyond a macrospin model to understand switching properties in ns regime.