SPRAM with large thermal stability for high immunity to read disturbance and long retention for high-temperature operation

We investigate the effect of temperature on current-induced magnetization switching in SPRAM (spin-transfer torque RAM) consisting of MgO-barrier-based magnetic tunnel junctions (MTJs) with a synthetic ferrimagnetic recording layer (SyF) by comparing the MJTs to those with a single ferromagnetic recording layer. It is found that SPRAM using MTJs with a SyF has two advantages for high-temperature operation: 1) A thermal stability factor E/k_BT as high as 64 at 150degC, which would ensure ten-year retention and ten-year immunity to read disturbance; and 2) an increase of the aspect ratio in the SyF, which leads to high coercivity H_C, resulting in two stable states (ldquo0rdquo or ldquo1rdquo) at high temperature.