Magnetoelastic phenomena in UNiGa

Results of dilatometric studies on UNiGa single crystals with respect to temperature, magnetic field and hydrostatic pressure are presented. Similar to the magnetism and the electrical-transport properties, also the elastic and magnetoelastic properties are strongly anisotropic. The linear thermal expansion coefficient α along the a-axis (αa) is always positive, whereas αc is negative up to 70 K. Sharp anomalies in both αa and αc are observed at the magnetic phase transitions. The antiferromagnetic ordering at low temperatures is accompanied by a considerable linear spontaneous magnetostriction of different signs along the a- and c-axis. In the analysis and discussion of these results in conjunction with magnetic and other electronic properties, the anisotropic 5f-ligand hybridization and related exchange interactions are considered as principal mechanisms. (orig.)