Long-Time Relaxation of the Dielectric Response in Lead Magnoniobate

We measured the time dependencies of the dielectric permittivity of a single crystal lead magnoniobate in the zero-field--cooled regime. The logarithmic decay of the dielectric response was observed in the glassy phase. We measured the time from the moment of the field application for the phase transition from the glasslike to the field-induced ferroelectric state to take place, at temperatures below 220 K. The transition is accompanied by the emerging of the even harmonics of the permittivity. It is shown that ln depends linearly on both the inverse temperature and the inverse applied field strength.