Electrocaloric effect at the second-order phase transition in triglycine sulfate: High-resolution measurements of the field dependence

The field dependence of the electrocaloric effect at the second-order phase transition in triglycine sulfate is investigated using a direct, high-resolution method. A characteristic ΔT∝E2/3 dependence of the caloric temperature change is found right at the phase transition, which rapidly evolves to a complex field dependence within less than 1 K above the phase transition. An analytical expression for this complex field dependence is derived from the Landau–Devonshire theory which accurately describes the observed ΔT(E). In the ferroelectric phase below the phase transition, a linear field dependence is observed. Bipolar electric driving fields lead to additional dips to negative values of the temperature change here, which can enhance the overall electrocaloric effect in this regime.