Since it is undesirable to require an external magnetic field for on-chip memory applications, we investigate the use of a Rashba effective field alternatively for assisting the electric-fieldinduced switching operation of a three terminal perpendicular magnetic tunnel junction (pMTJ).By conducting macro-spin simulation, we show that a pMTJ with thermal stability of 61 can be switched in 0.5 ns consuming a switching energy of 6 fJ, and the voltage operation margin can be improved to 0.8 ns. Furthermore, the results also demonstrate that a heavy metal system that can provide large field-like torque rather than damping-like torque is favored for the switching.Spin transfer torque (STT) based magnetic random access memory (MRAM) has been extensively studied because of its potential to improve current memory systems 1-3 . However, the STT-MRAM 4 , whose cell structure consists of magnetic tunnel junctions (MTJ) and access transistors, requires a current density larger than 10 10 A/m 2 to write the bit cell, which inevitably results in large write energy (~100 fJ) 5-7 . To reduce the switching current, the switching time, unfortunately, has to be sacrificed 4 . Moreover, for a two terminal STT-MTJ, since writing and