Fractal Dynamics in a Single Crystal of a Relaxor Ferroelectric

Abstract

We report the high-resolution and broadband light-scattering spectroscopy of a single crystal of a prototypical relaxor ferroelectric, Pb(Mg(1/3)Nb(2/3))O(3). A self-similar broad central peak, whose intensity is expressed as I(ω) [Symbol: see text] ω(α) has been observed, indicating the presence of a fractal in the crystal. A strong correspondence exists between the temperature dependence of the exponent α and that of the reported behaviors of polar nanoregions. The estimated fractal dimension (d(f) ≈ 2.6) at low temperatures clearly indicates a percolation transition of the polar nanoregions at around 240 K.

Infrared, terahertz, and microwave spectroscopy of the soft and central modes in Pb(Mg1/3Nb2/Nuzhnyy1, Petzelt2, Bovtun3 et al. 2017Phys. Rev. B21160View full textAdd to dashboardCite

“…High-frequency dynamics of PNDs in PMN was alternatively investigated using inelastic light scattering [14]. Below T B , Koreeda et al [14] observed an increase of the reduced intensity of the quasi-elastically scattered light, which followed power-law dependence in a broad frequency range of 1-2000 GHz.…”

Relation between Fractal Inhomogeneity and In/Nb-Arrangement in Pb(In1/2Nb1/2)O3

“…The parameter D f was also determined based only on light scattering in the same way as in ref. 14 , assuming  = 1.32 and  = 1. …”

“…Therefore we can understand relaxors in the same conceptual framework as BaTiO 3 , using the Comes–Guinnier–Lambert model in which the dynamic PNRs in relaxors correspond to nanometre-sized regions with time-dependent polarization 7–10 . However, compared with BaTiO 3 , relaxors are still not clearly understood because of their complexity, which originates from fluctuating polar structures that spread over large length and time scales 11–14 . The generation of the wide distributions of characteristic lengths and timescales in relaxors can be attributed to the random electric fields produced by different ions occupying equivalent lattice sites 15,16 ; the investigation of the effects of random electric fields on the distributions of the characteristic length and time scales is thus necessary.…”

“…Although fractals are usually found in noncrystalline glasses, polymers and gels 17–20 , PNRs form clusters, nanodomains and microdomains, which generate fractal structures in crystalline relaxors over nanometre-sized regions 13,14,21,22 . In addition, although the fractal-and-fracton picture describes systems on a coarse-grained level, it deals well with a broad distribution of length and time scales.…”

“…Thus, the fractal picture provides a powerful technique for understanding relaxors. Fractals in relaxors are reported to change near phase transitions 13,14 , but few reports exist that treat the relaxor structure and dynamics in a unified approach, even though they are connected with each other. The present study addresses this issue using quasi-elastic light scattering (QELS) and diffuse synchrotron X-ray scattering experiments on Pb(In 1/2 Nb 1/2 )O 3 (PIN) to investigate the distribution of spatial structures and dynamics.…”