Fundamental magnetotransport anisotropy in R2Fe17 single crystals

Abstract

We have measured the resistivity and Hall effect of R2Fe17 (R=Y, Tb, and Gd) single crystals in the temperature T range 4<T<300 K and applied magnetic fields of up to 9 T. The anomalous Hall effect (AHE) is very anisotropic in these ferromagnets. The AHE resistivity, measured with an applied magnetic field H perpendicular to the c axis, is very large and varies quite linearly with the longitudinal resistivity ρ, but the AHE resistivity for H along the hard magnetization direction (H∥c axis) is much smaller and increases as ρ2. We argue that the latter is of the intrinsic origin and is brought about by quasidegenerate Fe d levels near the Fermi level.