Jack C. Sankey, Yong-Tao Cui, et al.
Nature Physics
A spin-transfer torque switched magnetic tunnel junction (MTJ) is a memory element in modern magnetic random access memory (MRAM), a CMOS-integrated technology that is being developed by semiconductor manufacturers. One electrode of the MTJ acts as a magnetically bi-stable “free-layer” (FL), determining the bit-state of a memory cell. Spin-transfer torque (or spin-torque, or STT) switches the magnetic state of the FL with respect to a reference-layer (RL) in the MTJ. Here I review our current understanding of the MTJ device physics governing spin-transfer-torque driven switching. Starting with some simple concepts based on macrospin assumptions, I will then review recent experimental results, and compare observations with macrospin expectation for a more realistic, observation-based quantitative description, beyond macrospin. I will also describe some unresolved scientific challenges that could further improve the MTJ performance for memory technology, and give a brief outlook.
Jack C. Sankey, Yong-Tao Cui, et al.
Nature Physics
Guohan Hu, D. Kim, et al.
IEDM 2019
D.C. Worledge, M. Gajek, et al.
IMW 2012
Jonathan Z. Sun, Philip Trouilloud, et al.
AIP Advances