In situobservation of the ferroelectric-paraelectric phase transition in a triglycine sulfate single crystal by variable-temperature electrostatic force microscopy

The ferroelectric-paraelectric phase transition of triglycine sulfate single crystal was investigated by variable-temperature electrostatic force microscopy. Near the Curie temperature TC, the evolution of ferroelectric domains with temperature was observed in situ. We have found that the domain structures are not thermally reversible until TC-2^∘C<T<TC, within which the domain density N diverges reversibly via (TC-T)^-η, with η=0.54±0.05, larger than is predicted by mean-field theory. The spontaneous polarization P in individual domains decreases continuously and reversibly to zero and eventually vanishes at TC. Quantitative analysis reveals that P²∝(TC-T).