Paramagnetic resonance study of fluctuations near phase transition in triglycine sulphate

The EPR line widths of the high and the low field resonances of Cr³⁺ in triglycine sulphate (TGS) show two distinct anomalous broadenings near T_c. One is associated with a change in the motional frequency of the hindered rotation of the NH₃ groups and the other is related to the fluctuation of the polarization. Just below T_c there is a two fold splitting of the resonances which has a$\text{(}\text{T}{}_{\mathrm{c}}\text{?}\text{T}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ temperature dependence indicating the local geometry about the Cr³⁺ ion is determined by mean field theory.