EPR studies on BEDT-TTF intercalated MnPS 3 molecular magnet

Abstract

Frequency and temperature dependence of magnetic properties of BEDT-TTF intercalated molecular magnet MnPS 3 have been studied by electron paramagnetic resonance (EPR) technique at X-, K-,and Q-bands. A very strong and relatively narrower (than expected 400–500 G from overlapped six hyperfine transitions of paramagnetic Mn 2+ ion) single EPR peak in X-band spectra has been observed at all the temperature range, implying collective precession of Mn 2+ spins. The EPR signal intensity and linewidth were observed to change dramatically at about 45 K, indicating a magnetic phase transition. However, a very sharp decrease in EPR signal intensity and accompanying line bradening below T C indicates a very strong spin canting (and frustration) at lower temperatures. Some small and relatively smooth changes at about 30, 100 and 185 K are appeared as well. An almost linear dependence of resonance field to frequency has been observed for K- and Q-band spectra. By the analysis of the frequency dependent resonace field of EPR signal, the effects of the internal field is refined and thus the spectroscopic g-factor and internal field were determined to be g=1.9773 and H i =104 G , respectively. However, a very small non-linearity in H r versus frequency curve was atributed to the external field dependency of the internal field through magnetic susceptibility.