We report on a thermal-expansion (TE) and magnetostriction (MS) study of the antiferromagnet UNiAl at temperatures 2-90 K and in magnetic fields up to 16.5 T applied along the c-axis. The TE along the c-axis (in 0 T) exhibits a broad valley centered around 35 K. This anomaly is nearly removed in 16.5 T. For T≤7K a sharp metamagnetic transition (MT) observed in UNiAl at 11.4 T and it is accompanied by abrupt MS effects of + 1.3 × 10-4 and -1.8 × 10-4 along the a- and c-axis, respectively. In fields above the MT a negligible additional negative MS is induced along c-axis whereas the a-axis and consequently the volume expand considerably, which indicates a field-induced enhancement of the U magnetic moment. T>7K, the MT becomes gradually smeared out but a non-negligible MS is observed even for T >TN In the light of these results the TE anomaly measured in zero field may be attributed to AF that survives at temperatures far above T N.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering