²⁹Si NMR Studies of an “Unusual” Paramagnet FeSi —Anderson Localized State Model—

Abstract

²⁹Si NMR as well as magnetic susceptibility and electrical resistivity measurements have been performed on an “unusual” paramagnet FeSi. It is shown that the observed low temperature properties—such as the asymmetric shape of the ²⁹Si spin-echo spectrum and the exp (T^−1⁄4) type temperature dependence of the resistivity—can be explained consistently by considering the existence of the Anderson localized states (caused presumably by some residual imperfections of the crystal) with intra-state correlation. At higher temperatures, it is suggested from the temperature dependences of the ²⁹Si spin-lattice relaxation time and the resistivity that the thermodynamical properties are governed by the correlated modes of spin fluctuations with strongly temperature-dependent amplitude.