Electrical and Magnetic Properties of Holmium Single Crystals

Magnetic moment measurements have been made on holmium single crystals (hcp) over the range 1.3 to 300°K in magnetic fields from 250 to 18 000 Oe with the field applied along the $c$ axis, the $a$ axis, and a $〈10\overline{1}0〉$ direction. The $〈10\overline{1}0〉$ direction is the direction of easy magnetization with an extrapolated effective moment per atom at saturation of 10.34 Bohr magnetons. Basal plane measurements showed antiferro-magnetism below the Néel temperature of 132°K with basal plane anisotropy occurring below 80°K. Below the Néel point, an anomalous type of transition to ferromagnetic behavior upon application of sufficient field was observed. Magnetization curves for the $c$ axis are linear down to 60°K, while measurements below 20°K show an initial magnetization of approximately 1.7 Bohr magnetons followed by nearly linear magnetization curves. Electrical resistivity measurements were made from 4.2 to 300°K. For the $a$ axis, the resistivity changes slope slightly at 20°K. A larger change in slope occurs at the Néel temperature of 132°K. For the $c$ axis, the resistivity changes slope slightly at 20°K, reaches a peak at 120°K, goes through a minimum at 132°K, and remains constant until approximately 150°K, after which it increases linearly with increasing temperature.