The polar correlations in relaxor ferroelectrics (REFs) are usually considered as being promoted by quenched random electric fields (RFs). Within this approach the local polarization of individual PNR is controlled by the fluctuations of the RFs and thus precludes macroscopic ferroelectric symmetry breaking, even if uniformly charged chemically ordered regions counteract as observed in the heterogeneous relaxor-like lead magnesium niobate, PbMg1/3Nb2/3O3 (PMN). These PNR interact dipolarly and consequently, on cooling, a cluster-glassy ground state sets in at Tg [1]. On the other hand, below Tg the observed unusual dielectric response of REFs originates from the side-wall motion of mesoscopic domains [1]. Actually the glassy state concept versus a microdomain model is still puzzling [2]. One of the experimental possibilities for distinguishing between these two models is to study effects of aging. While the domain-like growth typically displays cumulative aging, the aging in glassy systems includes characteristic rejuvenation and memory effects. The goal of this contribution is to report results of our systematic studies of the aging processes in the canonical PMN and the uniaxial strontium-barium niobate (SBN) realaxor systems in the vicinity of their glass temperatures. The experimental results confirm the superdipolar glassy scenario of relaxors as their dominant ground state.
References
[1] W. Kleemann and J. Dec, Phys. Rev. B 94, 174203 (2016)
[2] Y. Uesu, H. Tazawa, K. Fujishiro, and Y. Yamada, J. Kor. Phys. Soc. 29, S703 (1996).