Induced magnetic form factor of chromium

Abstract

Expressions in terms of Bloch wave functions are derived for the induced nondiagonal magnetic susceptibility $\chi (\overrightarrow{\mathrm{G}},0)$. The expressions for the important contributions are shown to reduce in the tight-binding limit to the usual Pauli spin, Van Vleck orbital, and core diamagnetic terms. Each of these contributions was evaluated for Cr using augmented-plane-wave energy bands and wave functions. The results are in good agreement with the recent measurement of the induced magnetic form factor by Stassis, Kline, and Sinha if an exchange enhancement factor of 2.53 is assumed for the spin contribution. The calculated orbital form factor is isotropic and is essentially identical to the free-ion orbital form factor of Freeman and Watson. The limitations and reasons for the sucess of the free-ion model are discussed.