Perpendicular-Anisotropy CoFeB-MgO Magnetic Tunnel Junction

Ikeda et al., "A perpendicular-anisotropy CoFeB-MgO magnetic tunnel junction" (Nature Materials 9, 721-724, 2010; published online 11 July 2010; DOI 10.1038/nmat2804). Earlier perpendicular-anisotropy electrodes (rare-earth/transition-metal alloys, L10 (Co,Fe)-Pt alloys, Co/(Pd,Pt) multilayers) did not combine high thermal stability at small size, low switching current and a high tunnel magnetoresistance ratio. The authors instead use the interfacial perpendicular anisotropy between the ferromagnetic electrodes and the barrier in the CoFeB-MgO system already used for giant tunnel magnetoresistance in in-plane junctions (its reference list cites Parkin et al. 2004, the 2004 node). Their Ta/CoFeB/MgO/CoFeB/Ta perpendicular junctions show a tunnel magnetoresistance ratio over 120%, high thermal stability at diameters as low as 40 nm, and a switching current of 49 microamperes. The abstract frames memory and logic chips as a potential use, not a product.