Spontaneous and induced surface piezoresponse in PbMg_1/3Nb_2/3O₃single crystals

Abstract

The polarization state of relaxor PbMg 1=3 Nb 2=3 O 3 single crystals was studied using piezoresponse force microscopy. Areas of correlated polarization with a size of $50 nm were observed in the nominally ergodic relaxor state. These areas were attributed to ensembles of frozen polar nanoregions, which may exist in vicinity of the sample surface. Relatively strong piezoresponse could be induced by applying a dc electric field. After removing the field, a relaxation of the piezoelectric signal obeying power time dependence was observed. This induced piezoresponse was attributed to a contribution from dynamic polar nanoregions.

Polar nanoregions and diffuse scattering in the relaxor ferroelectric PbMg1/3Nb2/3OPaściak1, Welberry2, Kulda3 et al. 2012Phys. Rev. B

“…This is interpreted in terms of surface-induced local symmetry breaking within an otherwise cubic structure. 10,11 Thus, a nanoscale picture of PNRs in PMN is not revealed.…”

Evidence for anisotropic polar nanoregions in relaxor Pb(Mg1/3Nb2/3)OStock1, Gehring2, Hiraka3 et al. 2012Phys. Rev. B264250View full textAdd to dashboardCite

“…28,29 Subsequent neutron-based strain experiments found a significant skin effect in large single crystals of PMN as well that has since been observed with x rays, 26,[30][31][32] and local regions of polarization have been directly imaged near the surface using piezoresponse force microscopy. 33 Under the application of strong electric fields, the bulk unit cell in PMN remains cubic, whereas the structure of the near-surface region distorts; however, the intensity of the diffuse scattering arising from short-range polar correlations can be suppressed by an external electric field, but only below the critical temperature T C ∼ 210 K, which is indicative of a more ordered structure in the material. 31,34 In view of these results, we believe that the dielectric properties of both PMN and PZN can be described in terms of just two temperature scales: a high-temperature scale T d , below which static, short-range polar correlations first appear, and a low-temperature scale T C , below which long-range ferroelectric correlations can be induced by cooling in the presence of a sufficiently strong electric field.…”

Macroscopic and local piezoelectric properties of Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals exhibiting giant piezoelectric response

“…21 In PFM experiments an applied electric field does not affect substantially the static component of polarization, but the induced piezoresponse is mainly due to alignment of dynamic PNRs by the field. [21][22][23] After the bias field is switched off, the induced PFM signal relaxes rapidly with time. Therefore the shape of the hysteresis loops in PMN and PMN-0.1PT is mainly controlled by the dynamic order parameter.…”