Ultralow resistance-area product of 0.4 Ω(μm)2 and high magnetoresistance above 50% in CoFeB/MgO/CoFeB magnetic tunnel junctions

An ultralow resistance-area (RA) product of 0.4 Omega(mu m)(2) was achieved in CoFeB/MgO/CoFeB magnetic tunnel junctions with a high magnetoresistance ratio of 57% at room temperature. Various growth conditions for polycrystalline MgO(001) tunneling barrier were optimized to improve the crystalline orientation of the MgO(001) layer, which resulted in a significant enhancement of magnetoresistance in an ultralow RA region below 1 Omega(mu m)(2). Removal of residual H2O molecules from a growth chamber was especially effective in improving the crystalline orientation. The present achievements will enable the development of highly sensitive read heads for ultrahigh-density hard disk drives.