SPINTRONICS Perpendicular all the way

Magnetic tunnel junctions (MTJ) are thin-film structures consisting of two conducting magnetic layers separated by a very thin insulating barrier. A commonly adopted material for MTJs is the CoFeB-MgO multilayer system, which produces a giant TMR ratio with in-plane magnetization. The focus of the efforts has been on complex multilayers of magnetic transition elements such as Co and Ni, or Co and Fe with heavier nonmagnetic elements like Pt and Pd. The surprising discovery that CoFeB also shows large PMA opens a new path to the realization of high-performance, perpendicularly magnetized STT-MRAM. The work goes further to demonstrate the incorporation of this interface anisotropy in a device. The work by Ohno and colleagues opens new possibilities for high-performance STT-MRAM, and also poses basic questions.