Statistical Study of Large Voltage-Controlled Magnetic Anisotropy in 3X-nm Perpendicular Magnetic Tunnel Junctions

Switching of sub-50 nm perpendicular magnetic tunnel junctions (pMTJs) using the voltage-controlled magnetic anisotropy (VCMA) effect has been a persistent challenge in spintronics, especially as devices scale down. This work presents the first comprehensive study of 20 CoFeB/MgO-based 3X-nm voltage-controlled pMTJs with diameters of 30 to 36 nm. The devices consistently demonstrate large VCMA coefficients (mean $\xi ~\approx ~106$ fJ/Vm), which allow for achieving sub-nanosecond voltage-induced switching, and a mean tunneling magnetoresistance (TMR) greater than 130%. Endurance measurements show a lower bound of $2\times 10^{{10}}$ reliable write cycles. These results establish a high-VCMA pMTJ material stack for energy-efficient memory, sensing, and computing.