Elastic Properties of Purified Single-Crystalline Rhodium

A short overview is given of experimental investigations of single-crystalline rhodium which mainly focus on its elastic behaviour in the ultrasonic frequency range. In particular, temperature-dependent ultrasonic attenuation and sound-velocity measurements performed on a zone-refined single crystal below ambient temperature are reported. The exceptional acoustic quality of the sample permits investigations of the magnetoacoustic properties as well as the determination of the elastic stiffness coefficients over a broad frequency range with quite high accuracy. Especially those experiments which are governed by the main objective to investigate the influence of the electronic subsystem on both the sound velocity and the attenuation derive much benefit from this fact. As expected, the comparative analysis of all stiffness coefficients reveals a strong shear rigidity, indicating crystal forces that are strongly angular-dependent. These are not very reminiscent of ordinary metals and probably give rise to the peculiar mechanical properties commonly known from the polycrystalline material. Detailed studies of the temperature-dependent elastic moduli indicate that the electronic band structure of rhodium has to be taken into account for a satisfactory description of the elastic behavior.