Structure and magnetic properties of L10 CoPt(Ag/MgO,MgO) thin films

Disordered fcc (face-centered-cubic) [100] fiber-textured CoPt thin films with thicknesses of 20-40 nm were deposited on a nonmagnetic sputtered MgO seed layer with and without a Ag intermediate layer. These were subsequently annealed at 600-750 degrees C for 5-10 min using rapid thermal annealing (RTA). The structural variants were determined to coexist in the in-plane and normal to the plane directions after the RTA process. The MgO underlayer without the intermediate layer revealed strong in-plane anisotropy by magnetic hysteresis measurement. Selected area diffraction (SAD) by TEM and XRD measurements for these samples confirmed the preferential growth of in-plane variants of c axis compared to the perpendicular direction. High remanence and coercive squareness (S*) were obtained due to strong in-plane texture and especially due to exchange coupling among the grains. Evidence for this was provided by Delta M curves. Initial magnetization curves for samples annealed above 600 degrees C, showed the possibility of assembled single domain or domain pinning mechanism but with negligible free wall motion inside of the grains. (C) 2000 American Institute of Physics. [S0021-8979(00)61008-3].