The perpendicular anisotropy of Co40Fe40B20 sandwiched between Ta and MgO layers and its application in CoFeB/MgO/CoFeB tunnel junction

Magnetic anisotropy of Co40Fe40B20 thin films sandwiched between Ta and MgO layers was investigated. Magnetic properties of CoFeB layers deposited on top and bottom of MgO layer are different. The thickness of the CoFeB layer and annealing temperature are the critical parameters to achieve and keep the perpendicular magnetic anisotropy. The phase diagram of perpendicular anisotropic strength of CoFeB layers on annealing temperatures and thicknesses of CoFeB layers is observed. According to phase diagrams, perpendicular CoFeB/MgO/CoFeB tunnel junctions were fabricated, and tunneling magnetoresistance (TMR) ratio was higher than 30% at low temperatures.