Experimental and theoretical study of annealed Ni-Pt alloys

In this communication we present a detailed study of the magnetic properties of ordered Ni-Pt alloys. We study the alloys through field-cooled and zero-field cooled dc magnetization, nonlinear ac susceptibility and sound velocity and internal friction experiments. We also present a theoretical analysis of the magnetic moments in these alloy systems. Our analysis, both experimental and theoretical, will show that disorder has a large impact on the magnetism in the samples in the composition range of 40--60% Ni. We shall argue that any disorder still remaining in the annealed samples will crucially alter the magnetic moment in this composition range and is the most probable reason for the discrepancies between earlier experimental investigations.