Temperature dependence of Mn2+ EPR in Sn2P2S6 near the phase transition

Abstract

The X-band EPR spectrum of Mn2+ in Sn2P2S6 was studied in the temperature rangeT=223–363 K. At room temperature the spin-Hamiltonian constants areg=2.00±0.01,B20=(163±3)·10−4 cm−1,B22=(159±3)·10−4 cm−1,A=−(75±1)·10−4 cm−1. The effect of the invariance in temperature of the resonance magnetic fields in the narrow temperature rangeT=337–340 K and the model of the paramagnetic centre are discussed. According to EPR data a phase transition occurs atT=337 K. This transition from the paraelectric phase to the ferroelectric one is accompanied by a dramatic change in value of the spin-Hamiltonian constantB20.