Host NMR in dilute magnetic alloys: the spatial variation of the spin polarization

Abstract

The Hartree-Fock theory of the spatial dependence of the spin polarization in dilute alloys is developed in both cases of a 'magnetic' and 'nonmagnetic' impurity. It is shown that, in the latter case, the spin polarization should be reduced with respect to the asymptotic limit at rather large distances r of the impurity, such as k_FrF/ Delta sin eta , where eta is the phase shift at the Fermi level and Delta the width of the virtual bound state. Computer calculations of the host NMR spectra for real alloys, with a concentration c of impurities, show that the asymptotic limit for the spin polarization yields a broadening of the main line which increases linearly with c while for a typical case for a nonmagnetic impurity ( epsilon _F/ Delta =10, eta =¹/₂ pi ), a slower concentration dependence is derived.