Abstract :
Assuming that the material Ni(C5H5N)2Ni(CN)4 has a strong easy-plane anisotropy, we use a two-dimensional biquadratic planar rotator model to describe its thermodynamical behavior. Using an exchange coupling, J/kB=0.8 K and a biquadratic parameter D/kB=0.15 K, we have performed Monte Carlo simulations obtaining a good agreement with experimental data for the specific heat. Also, we have estimated the Berezinskii–Kosterlitz–Thouless (BKT) temperature as TBKT≈0.72 K and calculated the magnetic susceptibility.
