Aging in the ferroic random-field Ising model system strontium-barium niobate

Large aging effects, investigated via temporal dependences of the dielectric response, are found to be inherent in the uniaxial ferroelectric relaxor systems SBN:Cr and SBN:Ce. The results are discussed on the basis of domain coarsening and domain-wall pinning effects. Owing to the different charge disorder induced by the Cr³⁺ and Ce³⁺ dopants, a fundamental difference between both systems is established. While SBN:Ce shows only a weak breaking of ergodicity, the SBN:Cr system experiences true ergodicity breaking.