Dielectric and pyroelectric properties of (CH3NH3)3Bi2Br9crystals in the ferroelectric phase transition region

In order to elucidate the nature of the spontaneous polarization the temperature measurements down to 10 K in (CH3NH3)3Bi2Br9 have been performed. The low frequency dielectric relaxation along the a-axis in the vicinity of ferroelectric phase transition clearly indicates the complex nature of dielectric response below T c3. The measurements showed that both the migration of charges and ferroelectric domains contribute to the electric permittivity in the ferroelectric phase.