Theory of the Susceptibility and Magnetization of Alloys and Application to Palladium-Nickel Alloys.

The work to be presented in this thesis involves the construction within the random phase approximation of a generalized theory of local exchange enhancement for dilute and concentrated alloys. The theory allows one to calculate the susceptibility of a cluster embedded in an effective medium including exchange enhancement both within the cluster and the effective medium. Moreover, it allows one to calculate the moment on every site within the cluster and in the surrounding medium either in a magnetic field or in the presence of spontaneous moments. The theory is applied to paramagnetic and weakly ferromagnetic Pd -Ni alloys and is compared with magnetization and susceptibility measurements on those alloys.