Surface Domain Structures and Mesoscopic Phase Transition in Relaxor Ferroelectrics

Abstract

International audienceRelaxor ferroelectrics are a prototypical example of ferroic systems in which interplay between atomic disorder and order parameters gives rise to emergence of unusual properties, including non-exponential relaxations, memory effects, polarization rotations, and broad spectrum of bias- and emperatureinduced phase transitions. Despite more than 40 years of extensive research following the original discovery of ferroelectric relaxors by the Smolensky group, the most basic aspect of these materials - the existence and nature of order parameter - has not been understood thoroughly. Using extensive imaging and spectroscopic studies by variable-temperature and time resolved piezoresponse force microscopy, we fi nd that the observed mesoscopic behavior is consistent with the presence of two effective order parameters describing dynamic and static parts of polarization, respectively. The static component gives rise to rich spatially ordered systems on the 100 nm length scales, and are only weakly responsive to electric fi eld. The surface of relaxors undergoes a mesoscopic symmetry breaking leading to the freezing of polarization fl uctuations and shift of corresponding transition temperature

Ferroelectric or non-ferroelectric: Why so many materials exhibit “ferroelectricity” on the nanoscale

“…In many cases, non-classical ferroelectric behavior was reported, including a continuous spectrum of polarization values and relaxation via uniform contrast change, strongly reminiscent of relaxor ferroelectrics. [217][218][219][220][221][222] The hysteresis loops also rarely displayed saturation, unlike in a traditional ferroelectric. Remarkably, no clear delineation between these cases were found -classical ferroelectrics can demonstrate these abnormal contrasts, whereas many non-ferroelectric materials show remnant states and hysteresis loops.…”

Fano resonance and dipolar relaxation in lead-free relaxors

“…Owing to their fundamental interest and also technological promise, relaxors have been studied by various techniques since their discoveries. For instance, they have been investigated by Raman, neutron elastic diffuse scattering, extended X-ray absorption fine structure, high-resolution tunnelling electron microscopy, piezoresponse force microscopy, phenomenology and numerical simulations 7,13,19,20,26,27,[36][37][38][39][40][41] . On the other hand, there is an important aspect of their properties that has been much less documented because of experimental and computational challenges to overcome, that is, their terahertz (THz) dynamics 25,27,42,43 .…”

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

“…It was argued that in such case two polarization components coexist in relaxors: static and dynamic ones related to the mesoscopic labyrinthine domains and still dynamic PNRs, respectively. 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.…”