The tetragonal compound UNi2Si2 in zero magnetic field exhibits three different antiferromagnetic phases below TN = 124 K. They are characterized by the U moments parallel to the c axis, forming ferromagnetic basal planes and by a propagation vector q= (0,0, qz). Consequently, below TN two order-order magnetic phase transitions are observed; namely, at T1 = 108 K and T2= 40 K. The later two transitions are of the first order type. All three magnetic phase transitions are reflected by the pronounced anomalies of bulk thermodynamic properties such as thermal expansion, resistivity, susceptibility, and specific heat. Here we present the analysis of specific heat data going beyond the harmonic approximation. Realistic values of magnetic specific heat and magnetic entropy were obtained by this approach. An additional exponential contribution to the specific heat and resistivity below T2 is considered. It is attributed to the anisotropy induced gap in the magnetic excitation spectrum.
|Number of pages
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2001
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics