Effect of Impurities with Localized Moment on Spin Density Wave

Abstract

The effect of both the Spin interaction and potential interaction between impurities and conduction electrons on the spin density wave (SDW) is studied on the basis of a simple single-band model. The impurity spin is treated as a classical spin. In the case of the SDW containing one impurity the energy and spin density of a localized state within the energy gap are calculated. For a finite concentration the Néel temperature, T N , and the order parameter at absolute zero, Δ (0), are calculated by applying the Abrikosov-Gorkov theory of superconductivity. It is found that the impurities have two effects: depairing effect similar to that in superconductivity and pairing effect arising from the antiferromagnetic alignment of the impurity spins that follows the SDW polarization. The competition of these effects affects the behavior of T N and Δ (0). Calculated results can be compared qualitatively with experimental data on Cr-Fe and Cr-Co alloys.