On Indirect Knight Shift and NMR in Ferromagnetic Metals Part I. General Formulation and Qualitative Discussions

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Abstract
It is well-known that the exchange-polarized core s -electrons by partially filled magnetic d -band electrons are able to make characteristic contributions to effective magnetic field felt by nucleus within crystal, which leads to temperature-dependent and negative Knight shift (indirect Knight shift) and nuclear magnetic resonance absorption in ferromagnetic metals. The mentioned exchange-polarization of core s -electrons has been worked out quantitatively only for the case of isolated atom and ion, and the extension to the crystal electrons in energy band has not been worked as yet mainly for the formidable labour of numerical computations. In view of the above situation we have adopted the perturbation-theoretic approach for working the mentioned problem. The empirical formula of indirect Knight shift by Clogston et al. and of NMR in ferromagnetic metals by Portis et al. have been derived successfully and the extension of our formalism to dilute ferromagnetic alloys has been worked.