High electric fields and surface layers in very thin single crystal plates of triglycine sulfate

We have recently seen drastic changes of electrical properties in newly available very thin single crystal plates of triglycine sulfate. They can be considered as arising from a high internal field (1 MV/m in a 1 μm thick plate cut perpendicular to the axis, electrodes short circuited).This electric field is explained in a new phenomenological surface-layer model where spontaneous polarization slightly increases at the surface.From the experimental data the surface layer thickness e0/2 and the change of spontaneous polarization are estimated at 20°C for a 1 μm thick plate:image omitted The surface layer has specific properties: higher Curie temperature than the bulk, smaller dielectric constant and its external part is in a depolarizing field, but small enough (33 MV/m) to permit a metastable state.