Electrocaloric effect in triglycine sulfate under a strong internal bias field

The influence of an internal bias field on the electrocaloric effect in triglycine sulfate is experimentally investigated by a direct, time-resolved high-resolution method. The internal bias field strongly modifies the dynamic caloric temperature change ΔT(t) and the field dependence ΔT(E). While the normal electrocaloric effect is observed for electric fields along the internal bias field, a strong inverse electrocaloric effect leads to negative values for the caloric temperature change for reverse electric fields. The strength of the reverse electric field further allows one to tune the electrocaloric effect from a purely inverse effect to a sequence of inverse, normal, and again inverse effects within a single field cycle. These effects persist from the ferroelectric up to the paraelectric phase.