On magnetic first-order transitions in erbium

The magnetic transitions in a single crystal of Er have been investigated with a high-resolution scanning microcalorimeter. The transition between the ferro-and antiferromagnetic states takes place at 19.2K (T) and is of first order with a latent heat of 18.5 plus/minus 1.0 J mol exp --1 . In the antiferromagnetic state between T sub c and 51K four small energy peaks were observed which are ascribed to commensurate transitions. These transitions exhibit hysteresis effects and are of first order. At 53.4K a relatively localised energy peak of 1.3 plus/minus 0.3J mol exp --1 was found which probably arises from the ordering of the basal-plane moments. Also this transition was found to have a temperature hysteresis and is of first-order type. The antiferro--paramagnetic transition occurs at 85.6K in this sample and its second-order nature is confirmed. 14 ref.--AA