Magnetocrystalline Anisotropy of Ni-Pt Alloys

The magnetocrystalline anisotropy energy has been measured for Ni-Pt alloys containing 0 ∼50 at% Pt in the temperature range from 4.2 K to 300 K by the use of the torque method. At 4.2 K, anisotropy energy varies drastically accompanying a change in sign at about 5 at% Pt and shows a maximum at about 15 at% Pt, followed by the second change in sign at about 35 at% Pt. As temperature is raised, the change in sign is observed for 5 at% Pt alloy.