Abstract
The adiabatic elastic constants of holmium were determined in the temperature range from 78 to 300 K, using high-purity single crystals. The constants were obtained from the ultrasonic-wave velocities (20 MHz) measured by the pulse-superposition method. The values of the constants at room temperature in units of 1011 dyn/cm2 are c33 =8.015, c44=2.592, c11 =7.612, c12=2.600, and c13 =2.072. Using these values, the Debye temperature was computed to be 181 K. The sound velocities tend to vary with temperature in an anomalous fashion near the Néel temperature (TN=131 K). Attenuation and sound-velocity measurements near TN permit an estimate of the relaxation time for spin fluctuations, which was found to be 3×10−10 sec.