Ultrasonic Study of a Single Crystal Gd₇₀Y₂₀Lu₁₀ Alloy in a Magnetic Field

Abstract

Ultrasonic attenuation and sound velocity have been measured for a single crystal of the Gd₇₀Y₂₀Lu₁₀ alloy in external magnetic fields up to 6.5 kOe and over the temperature range 160–230 K which includes the ferromagnetic and screw antiferromagnetic states. Several anomalies observed in attenuation and velocity measurements are analyzed together with the magnetization data to construct the magnetic phase diagram. The large peak in attenuation and the large drop in velocity observed only on the warming-up process are attributed to the reorientation of the spins inside and just outside of the domain wall. An attenuation peak observed within the region of the fan phase is interpreted as the peculiar one originating from the spin structure of the fan phase.