Critical slowing down in the single crystalline relaxor SBN75

The dielectric susceptibility of strontium-barium niobate, Sr0.75Ba0.25Nb2O6, reveals strong relaxor behaviour. It is shown that the relationship between the frequency of the ac probing field and the temperature, at which the real part of the susceptibility passes through a maximum, satisfactorily follows the activated dynamic scaling law predicted for the random-field Ising model. Applicability of a power law as suggested by the dynamic scaling theory is discussed.