Anisotropy energy measurements on single-crystal ${\mathrm{Tb}}_{0.15}$${\mathrm{Ho}}_{0.85}$${\mathrm{Fe}}_2$

The magnetocrystalline anisotropy energy constants $K_1$ and $K_2$, have been examined for a ${\mathrm{Tb}}_{0.15}$ ${\mathrm{Ho}}_{0.85}$1${\mathrm{Fe}}_2$ single crystal at various temperatures between 33 and 325 K using torque-magnetometry techniques. The data show that $K_1$ and $K_2$ are very sensitive to temperature changes in this range, and have room-temperature values of -2.2 × ${10}^5$ and 1.1 × ${10}^6$ ${\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{s}/\mathrm{c}\mathrm{m}}^3$, respectively. A comparison of the room-temperature values of $K_1$ with the values reported in the literature for the binary compounds Tb${\mathrm{Fe}}_2$ and Ho${\mathrm{Fe}}_2$ shows that $K_1$ for the pseudobinary is smaller than the values reported for the binary compounds by factors of 265 and 87, respectively. The low room-temperature anisotropy constants observed for the pseudobinary compound are also consistent with the prediction of the single-ion model of anisotropy and the behavior suggested by the Mössbauer-effect studies of Atzmony et al. Because of their small anisotropy constants and large magnetostriction, the pseudobinary compounds may be potentially useful in magnetostrictive-device applications. It was further found that easy direction of magnetization undergoes several reorientations as the temperature is increased from 33 to 325 K. A comparison of our data with the data obtained from Mössbauer-effect studies on powder samples, shows the two results to be in rather good agreement at low temperatures. At high temperatures the results differ in that the Mössbauer-effect studies suggest the presence of a triple point.