Figure 1

Two established types of $E\mathrm{\text{−}}T$ phase diagram for PMN [110]. (a) Random field (RF) scenario: theory [19, 20] predicts the existence of microscopic ferroelectric (FE) ordering at $T=T_C$ in zero field. Experiments by Fu et al. [18]: $T_C\sim 225\mathrm{K}$. Solid line: schematic conversion line where nanodomains subject to random fields RFs undergo a FE phase transition in a bias field $E$. (b) Dipolar glass model with randomly interacting PNRs. Solid lines with horizontal arrows: first order phase transition line between nonergodic relaxor and ferroelectric phase as observed in isofield experiments. Solid circles: data obtained from polarization and heat capacity anomalies [cf. Figs. 2a, 2b]. Solid line with vertical arrow: same but for isothermal experiments. Open circles: data from polarization and calorimetric measurements [cf. Figs. 2c, 3a]. CP and dashed line denote the critical point and the Widom line [35], respectively.Reuse & Permissions

Figure 2

Electric field and temperature evolution of the polarization and excess specific heat obtained in the single crystal PMN along the [110] axis. (a) Hysteresis loops obtained at different temperatures (see upper panels). Temperature evolution of the polarization is shown in the bottom left panel. Discontinuous change of the polarization in isothermal experiments is presented for several temperatures in the bottom right panel. (b) Temperature dependence of the excess specific heat data obtained in the ac mode at various constant bias electric fields. (c) Discontinuous steps in the polarization (open circles) and specific heat (solid circles) are observed when isothermally crossing the ferroelectric conversion line.Reuse & Permissions

Figure 3

(a) Change of the sample temperature for the PMN [110] single crystal as a consequence of the released latent heat at the field induced ferroelectric transition measured at several constant bath temperatures. The inset at 230 K shows the change of sample temperature under electric field reversal. (b) Released latent heat and total enthalpy change at the ferroelectric conversion as determined by high resolution calorimetry.Reuse & Permissions