Magnetic properties of very thin single and multilayer NiFeCo and CoFe films deposited by sputtering

As the size of the giant magneto resistive (GMR) devices continues to decre ase into submicrometer regime, the demagnetizing field from the magnetic la yers will increase to very high values, prohibiting switching with a reason ably small current. The most feasible way to reduce it is to make the magne tic layers thinner. Single layers of NiFeCo and CoFe films as well as multi layers consisting of these with various underlayers have been deposited by rf diode sputtering in a magnetic field. NiFeCo becomes nonmagnetic at 15, 10, and 6 Angstrom when using Ta, Si3N4, and Cu underlayers, respectively. The magnetization of NiFeCo films sandwiched with Cu decreases as the films become thinner, indicating that about one atomic layer loses its magnetic moment at each interface with Cu. The induced magnetic anisotropy is a stro ng function of the NiFeCo film thickness, changing from 7 Oe for 20 Angstro m to 17 Oe for 100 Angstrom. CoFe films lose very little magnetic moment at the interfaces with Cu. Multilayers of [NiFeCo/Cu/CoFe/Cu] with different Cu underlayer thickness have been made and the magnetic and GMR properties show a strong dependence on the Cu buffer layer thickness due to different interface roughnesses. With proper designing of the interfaces, these very thin magnetic films have high potential for ultrahigh-density magnetic memo ry and other applications. (C) 1998 American Institute of Physics. [S0021-8 979(98)37711-7].