Anomalous and Ordinary Hall Effect in Terbium

Abstract

The anomalous and ordinary Hall coefficients R_s and R₀ defined by the relation ρ_H≡R₀B+R_s4πM have been obtained for single‐crystal Tb in both ordered and paramagnetic states. Results for the component of the Hall resistivity ρ_H characterized by H (and M) in the basal plane 101̄0 easy axis in Tb) show that ρ_H is linear in H above T_N and exhibits a strong temperature dependence which is almost entirely due to that of the magnetic susceptibility. R_s is found equal to −40.4×10⁻¹² Ω·cm/G and temperature independent. Below T_N the anomalous coefficient found from the saturation Hall resistivity reverses sign, passes through a maximum near 140°K (where R_s=+22.4×10⁻¹² Ω·cm/G) and falls to 0 below 30°K. Possible mechanisms for this unique sign reversal in R_s are discussed. The T‐independent nature of R_s above T_N plus a linear dependence of R_s on the derived magnetic resistivity below 120°K indicates that thermal disorder of the 4f spin system is the dominant scattering mechanism in the Hall effect. The normal coefficient is essentially temperature independent above approximately 260°K (R₀=−1.0×10⁻¹² Ω·cm/G) and below 90°K. At intermediate temperatures R₀ rises to a positive maximum of +8.8×10⁻¹² Ω·cm/G at 205°K. Hall resistivity data above T_N with H along 〈0001〉 directions (second independent component in hcp symmetry) give significantly larger values of R_s and R₀ reflecting the Fermi surface anisotropy.