The thermal expansion of single-crystalline UNi2Si2 along the a and c axes has been measured with high accuracy. The linear thermal expansion is found to be highly anisotropic and to show a spontaneous magnetostriction. In the ground state, the spontaneous volume magnetostriction reaches 4 × 10-4. The lattice volume changes abruptly at T1 = 43 K and T2 = 103 K, where UNi2Si2 undergoes the magnetic phase transitions. When increasing temperature, a considerable volume expansion (by 3.6 × 10-8 m3 mol-1) at T1 and tiny shrinkage (by 6.5 × 10-10 m3 mol-1) at T2 have been observed. On the other hand, no apparent volume effect is observed around the magnetic ordering temperature TN = 124 K. Thermal expansion data are analyzed using thermodynamic relations in order to elucidate the previously published pressure dependences of temperatures of magnetic phase transitions T1, T2, and TN.
|Number of pages||5|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2001 Nov 1|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics