Magnetic properties and specific heat of MPS3 (M = Mn, Fe, Zn)

The magnetic properties and specific heat of MPS3 (M = Mn, Fe and Zn) have been investigated. While ZnPS3 is nonmagnetic, MnPS3 and FePS3 are antiferromagnets with the Neel temperature T-N of 78 and 118 K, respectively. Nevertheless, the specific heat of MnPS3 and FePS3 is smaller than that of ZnPS3 below about 20 K. The temperature dependence of the magnetic specific heat C-M of MnPS3 shows a broad hump which is characteristic to the two dimensional magnetic materials and a small sharp peak at T-N. On the other hand, that of FePS3 shows a large sharp peak at T-N. As for FePS3, the temperature dependences of the magnetization M and C-M are well reproduced by taking account of the magneto-elastic effect which introduces an additional term proportional to the square of the average value of the spin to the exchange coupling constant. As for MnPS3, marked two dimensional characters apear in the temperature dependence of M and C-M. The observed T-N is much smaller than the paramagnetic Curie temperature of 240 K obtained from the temperature dependence of the magnetic susceptibility at high temperature. (C) 2003 Elsevier B. V. All rights reserved.