Transverse magnetoresistance in terbium and holmium single crystals

The transverse magnetoresistance of single crystals of terbium and holmium metals in their low-temperature ferromagnetic phase has been investigated in magnetic fields up to 80 kOe. Around 4 K the resistance of the basal-plane crystals increases with the field. As the temperature approaches the Curie temperature, the resistance isotherms show a maximum at low field and a gradual decrease at higher fields. For Tb metal when $\overrightarrow{I}\parallel 〈11\overline{2}0〉$ and $\overrightarrow{H}\parallel 〈10\overline{1}0〉$, the maximum appears around 14 kOe, while for $\overrightarrow{I}\parallel 〈10\overline{1}0〉$ and $\overrightarrow{H}\parallel 〈11\overline{2}0〉$ it is around 32 kOe. For both crystals around 30 K, the resistance increment at the maximum is approximately 2% of the zero-field resistance. When $\overrightarrow{I}\parallel 〈0001〉$ and $\overrightarrow{H}$ is parallel to the basal plane, the resistance isotherms around 4 K show a minimum at about 10 kOe, which is attributed to elimination of domain-boundary scattering. The increase in resistance at higher fields can be empirically described as $\Delta R\propto B^{2.4}$. For the Ho basal-plane crystals, the increase in the resistance around 4 K and above 20 kOe can be expressed as $\Delta R\propto B$. The isotherms around 10 K show a weak maximum ($\frac{\Delta R}{R}\approx 0.1\%$) at about 2 kOe. The results are discussed on the basis of the normal magnetoresistance, the domain resistivity, and the spin-wave resistivity.