Specific heat of ferroelectric TGSe under electric field: analysis in terms of Landau theory

Abstract

The specific heat of the ferroelectric-paraelectric phase transition in TGSe under several electric fields in the range 175-750 V cm −1 has been measured and analysed in terms of the same tricritical Landau potential obtained at zero electric field plus the term −ξ Q, which represents the simplest form to include the coupling between the order parameter Q and the electric field E (ξ ∝ E). Data in the ferroelectric phase have been successfully fitted and it has been found that ξ = k(E + E 0 ), where k is constant and E 0 ∼ 150 V cm −1 . It has been found that in order to describe the behaviour in both phases simultaneously it is necessary to consider a more complex coupling between the electric field and the order parameter, which makes the critical temperature and the coefficient of Q 6 in the tricritical potential be renormalized by the field.

First order phase transition in deuterated triglycine selenate under an electric field: experimental study and analysis in the frame of Landau theory

“…A similar behaviour was recently reported [4,21] for tricritical phase transition in TGSe after studying the influence of the electric field on the specific heat. Ferroelectric phase data for E = 0 were also explained by considering an effective field higher than the applied field.…”

“…On the other hand, the study of thermal properties, such as specific heat and latent heat, under an electric field and its comparison to theoretical models is unusual, unlike dielectric properties. As an example, studies of the second order phase transition in triglycine sulfate (TGS) [1,2], the tricritical phase transition in triglycine selenate (TGSe) [3,4] and the first order phase transition in KDP [5][6][7] should be mentioned.…”

Influence of a weak dc electric field on tricritical phase transition in TGSe: evidence of different specific heat behaviour on cooling and heating runs

“…Recently, we also studied the influence of a dc electric field in the phase transition of TGSe [5]. The specific heat was measured under several electric fields in the range 175-750 V cm −1 .…”

Memory effect in triglycine sulfate induced by a transverse electric field: specific heat measurement

“…These features have been applied for observing ferroelectric phase transitions specially in the influence of electric field and for measuring latent heat even in the neighborhood of a tricritical point where it is expected to be comparatively small. [11,19,20] The TGS crystal used in this experiment was produced by MolTech GmbH in Berlin. It was of the form of a rectangular parallelepiped with dimensions 7.0 mm × 7.0 mm × 4.0 mm along b × c, b, c and 302 mg in mass.…”