Interplay between static and dynamic polar correlations in relaxorPb(Mg1/3Nb2/3

Abstract

We have characterized the dynamics of the polar nanoregions in Pb͑Mg 1/3 Nb 2/3 ͒O 3 through high-resolution neutron-backscattering and spin-echo measurements of the diffuse-scattering cross section. We find that the diffuse-scattering intensity consists of both static and dynamic components. The static component first appears at the Curie temperature ⌰ ϳ 400 K while the dynamic component freezes completely at the temperature T f ϳ 200 K; together, these components account for all of the observed spectral weight contributing to the diffuse-scattering cross section. The integrated intensity of the dynamic component peaks near the temperature at which the frequency-dependent dielectric constant reaches a maximum ͑T max ͒ when measured at 1 GHz, i.e., on a time scale of ϳ1 ns. Our neutron-scattering results can thus be directly related to dielectric and infrared measurements of the polar nanoregions. Finally, the global temperature dependence of the diffuse scattering can be understood in terms of just two temperature scales, which is consistent with random-field models.

Role of random electric fields in relaxors

“…This behavior is markedly different from that in PMN (dashed lines) for which the TA phonon linewidth broadens enormously on cooling. The broadening in PMN has been shown to result from a coupling to a low-energy relaxational mode associated with the strong diffuse scattering (44,45). Assuming that a coupling of similar strength is present in PZT, then the comparatively weak temperature-dependent TA phonon broadening would further support our finding of little or no diffuse scattering in this compound.…”

Evidence for anisotropic polar nanoregions in relaxor Pb(Mg1/3Nb2/3)OStock1, Gehring2, Hiraka3 et al. 2012Phys. Rev. BSelf Cite254250View full textAdd to dashboardCite

“…As shown by a recent high-resolution spin-echo study of the elastic diffuse scattering in PMN, 35 the dynamics of relaxors also reflects these same two temperature scales. The onset of diffuse scattering at T d was found to coincide with the appearance of static (at least on gigahertz time scales) polar nanoregions that coexist with dynamic, short-range polar correlations.…”

“…T C was found to coincide with the temperature at which all short-range polar correlations are static (within experimental resolution). 35 These two temperature scales are also clearly seen in measurements of the bulk polarization in La-doped PbZr 1−x Ti x O 3 (PLZT) where T C marks the temperature at which the field-cooled and zero-field-cooled polarizations diverge. 36 These two temperature scales can be understood in terms of random dipolar fields that are introduced through the disorder that is inherently present on the B site of lead-based perovskite relaxors.…”

Development of nanoscale polarization fluctuations in relaxor-based (1-x)Pb(Zn1/3Nb2/Tsukada1, Hidaka2, Kojima3 et al. 2013Phys. Rev. B252250View full textAdd to dashboardCite

“…7,8 Anomalies in some physical properties around T * are sometimes regarded as a result of the nearsurface effect. 35 However, the anomaly in d /dT is found not only in a 180 • scattering geometry but also in a 90 • scattering geometry, which probes internal crystals. We can therefore conclude that the LA phonon anomaly at T * is an intrinsic effect.…”