Single-shot Measurements Of Spin-transfer Switching In Cofeb/mgo/cofeb Magnetic Tunnel Junctions

摘要

Real-time measurements of spin-transfer induced magnetization switching were performed at room temperature on elliptical CoFeB/MgO/ CoFeB magnetic tunnel junctions (60 × 170 nm~2) using a storage oscilloscope. Free layer thickness and thermal stability factor (K_u V/k_B T) were 2nm and 17, respectively. Under small dc current with short rise time (200 ps), the switching processes essentially comprised long waiting time and short transition time (less than 400 ps). We found, for the first time, that switching probability density was considerably lower for few ns after the rise of the current, and became constant later. Existence of this "non-reactive time" could be a critical issue for fast writing applications.