Field-induced sharp ferroelectric phase transition in Sr0.66Ba0.34Nb2O6 relaxor ferroelectric

Field-induced sharp ferroelectric phase transition was observed in Sr0.66Ba0.34Nb2O6 single crystals. The peaks of the real and imaginary parts of dielectric permittivity arise upon cooling under weak dc bias electric fields and subsequently heating under zero fields or upon cooling under zero fields and subsequently heating under weak electric fields. The applied electric field cancels the random fields that destroy the phase transition and give rise to low temperature domain state if E=0. These results strongly suggest that the SBN system belongs to the random field Ising universality class, a rare case among structural phase transitions.