Skew-Scattering-Induced Anomalous Hall Effect in Impurity-Doped Fe

Abstract

In this chapter, we investigate the AHE induced by skew scattering mechanism for impurity-controlled Fe. While recent theoretical and experimental works show that the AHE can be well explained by the Berry phase theory in most cases, Onoda et al. theoretically showed that the skew-scattering mechanism should be dominant in the clean-limit regime. Miyasato et al. investigated the AHE for nominally pure Fe to explore the clean-limit regime. They observed some crossover in this regime and assigned it to the intrinsic to extrinsic crossover. This kind of crossover behavior in Fe had already been reported in literature of decades ago (P.N. Dheer, Phys. Rev. 156, 637 (1967), A.K. Majumdar and L. Berger, Phys. Rev. B 7, 4203 (1973)). Nevertheless, the extrinsic skew-scattering-induced AHE in ferromagnets could hardly be analyzed quantitatively because of the difficulty in discriminating it from the nonlinearly $H$-dependent normal Hall conductivity in this region and because of the difficulty in theoretical elucidation. In this chapter, we examine the nature of the skew-scattering-induced AHE in impurity-controlled Fe. In the first section, we investigate the crossover from intrinsic to extrinsic mechanism caused by $T$ elevation in terms of the Lorenz ratio for nominally-pure, Si-doped, and Co-doped Fe. In the second section, we reveal the different nature of the skew-scattering mechanism between Co-doped and Si-doped Fe by systematic study on the impurity-element dependence.