Thermomagnetic properties near transitions of Tb6FeX2 (X = Sb, Bi)

The thermomagnetic properties of compounds Tb6FeX2 (X = Sb, Bi) near the magnetic transition were investigated. The ferromagnetic–paramagnetic transition of the two compounds is a typical second-order transition. The Landau theory of second-order phase transition is employed to investigate the thermodynamic transition temperature and the specific heat. The magnetic entropy change was also calculated. The specific heat jumps of the compounds Tb6FeSb2 and Tb6FeBi2 at Curie point are 36.5 and 41.2 J kg−1 K−1, respectively. The maximum magnetic entropy change of the compound Tb6FeBi2 is 2.68 J kg−1 K−1 occurring around 246 K, while the maximum magnetic entropy change of Tb6FeSb2 is 2.25 J kg−1 K−1 at 256 K.