Light-induced capacitance tunability in ferroelectric crystals

The remote controlling of ferroic properties with light is nowadays a hot and highly appealing topic in materials science. Here, we shed light on some of the unresolved issues surrounding light–matter coupling in ferroelectrics. Our findings show that the capacitance and, consequently, its related intrinsic material property, i.e., the dielectric constant, can be reversibly adjusted through the light power control. High photodielectric performance is exhibited across a wide range of the visible light wavelength because of the wavelength-independence of the phenomenon. We have verified that this counterintuitive behavior can be strongly ascribed to the existence of “locally free charges” at domain wall.Postprint (author's final draft

Light-induced strain and its correlation with the optical absorption at charged domain walls in polycrystalline ferroelectrics

Photostrictive materials have a growing interest because of their great potential as light-driven actuators, among other optomechanical applications. In this context, the optical control of macroscopic strain in ferroelectrics has recently attracted remarkable attention as an effective alternative to the conventional electric control of strain. Here, a clear correlation between optical absorption and light-induced strain in polycrystalline BaTiO3 is shown. Specifically, the grain size and the sample thickness dependence of optical absorption when the material is irradiated with energy photons lower than the band gap evidence that light absorption at charged domain walls is the core of the observed photo-response in ferroelectrics. The photoinduced electronic reconstruction phenomenon is proposed as the primary physical mechanism for light absorption at charged domain walls. Results open a new pathway to designing ferroelectric-based devices with new functionalities like thickness gradient-based photo-controlled nanoactuators.Postprint (published version

Photo-controlled ferroelectric-based nanoactuators

Finding a feasible principle for a future generation of nano-optomechanical systems is a matter of intensive research, because it may provide new device prospects for optoelectronics and nanomanipulation techniques. Here we show that the strain of a ferroelectric crystal can be manipulated to achieve macroscopic, stable, and reproducible dimensional changes using illumination with photon energy below the material bandgap. The photoresponse can be activated without direct light incidence on the actuation area, because the cooperative nature of the phenomenon extends the photoinduced strain to the whole material. These results may be useful for developing the next generation of high-efficiency photocontrolled ferroelectric devices.Postprint (updated version

Photo-controlled ferroelectric-based nanoactuators

Finding a feasible principle for a future generation of nano-optomechanical systems is a matter of intensive research, because it may provide new device prospects for optoelectronics and nanomanipulation techniques. Here we show that the strain of a ferroelectric crystal can be manipulated to achieve macroscopic, stable, and reproducible dimensional changes using illumination with photon energy below the material bandgap. The photoresponse can be activated without direct light incidence on the actuation area, because the cooperative nature of the phenomenon extends the photoinduced strain to the whole material. These results may be useful for developing the next generation of high-efficiency photocontrolled ferroelectric devices

Photocontrolled strain in polycrystalline ferroelectrics via domain engineering strategy

The use of photonic concepts to achieve nanoactuation based on light triggering requires complex architectures to obtain the desired effect.In thiscontext, the recent discoveryof reversible optical control of the domain configurationin ferroelectricsoffers anew light-ferroic interplaythat can be easily controlled. To date, however, the optical control of ferroelectric domains is explored insingle crystals, although polycrystals are technologically more desirable because they can be manufactured in a scalable and reproducible fashion. Here we report experimental evidencesfora large photo-strain response in polycrystalline BaTiO3that is comparable to theirelectro-strain values. Domainsengineering is performed through grain size control, thereby evidencing that charged domain walls appear to be the functional interfaces for the light-driven domain switching. Thefindingsshed light onthe design of high-performance photo-actuatorsbased on ferroelectric ceramics, providing afeasible alternativeto the conventional voltage-driven nanoactuatorsPostprint (author's final draft