Effects of Hydrostatic Pressure on the Magnetocrystalline Anisotropy ConstantK1of Ni–Pd and –Cu Alloys

The effects of hydrostatic pressure on the first magnetocrystalline anisotropy constant K 1 were measured on both Ni–Pd (∼40 at.%Pd) and Ni–Cu(∼19 at.%Cu) alloy systems in Ni rich regions by torque method. Measurements were made under pressures up to 6 k bar at 77 K for both Ni–Pd and –Cu alloys and at 273 K for Ni–Pd alloys. The pressure derivatives of K 1 , ∂ K 1 /∂ P , are all positive in sign for both alloy systems. At 77 K, ∂ K 1 /∂ P increases rather slowly with Pd content for Ni–Pd alloys, but it decreases rapidly with Cu for Ni–Cu alloys. The positive shift of K 1 with pressure and the different behaviour of ∂ K 1 /∂ P at 77 K for both alloy systems are discussed qualitatively on the itinerant electron model.