Abstract
Absence of inversion symmetry is the underlying origin of ferroelectricity, piezoelectricity, and the bulk photovoltaic (BPV) effect, as a result of which they are inextricably linked. However, till now, only the piezoelectric effects (inverse) have been commonly utilized for probing ferroelectric characteristics such as domain arrangements and resultant polarization orientation. The bulk photovoltaic effect, despite sharing same relation with the symmetry as piezoelectricity, has been mostly perceived as an outcome of ferroelectricity and not as a possible analytical method. In this work, we investigate the development of BPV characteristics, i.e. amplitude and angular dependency of short-circuit current, as the ferroelastic domain arrangement is varied by applying electric fields in planar devices of BiFeO3 films. A rather sensitive co-dependency was observed from measurements on sample with ordered and disordered domain arrangements. Analysis of the photovoltaic response manifested in a mathematical model to estimate the proportion of switched and un-switched regions. The results unravel the potential utility of BPV effect to trace the orientation of the polarization vectors (direction and amplitude) in areas much larger than that can be accommodated in probe-based techniques.
Highlights
The observation of the photovoltaic (PV) effect in BiFeO3 (BFO) has revitalized interests in the field of photo-ferroics, i.e. in the interplay between ferroic orders and photo-electronic characteristics
The origin of the PV effect in such scenarios has been found to be susceptible to the ferroelectric-electrode interface, and to the overall conduction of the gap[1]
The planar geometries used in this work allowed us to focus on the Isc originating from the bulk photovoltaic (BPV) effect, which is evident from the angular-dependent characteristics
Summary
The observation of the photovoltaic (PV) effect in BiFeO3 (BFO) has revitalized interests in the field of photo-ferroics, i.e. in the interplay between ferroic orders and photo-electronic characteristics. For certain applications, mere knowledge about the sign of polarization is not sufficient, and information about the orientation is desired This is true for planar devices wherein the electric fields are applied in-plane. Recent discovery pertaining to electric field control of sykrmions in bi-layered heterostructures will motivate further research in such devices[11] In all of these scenarios, knowledge about the in-plane polarization in terms of magnitude and orientation is necessary. The emitted light wave can be resolved to extract information about the polarization state, and distinguish between ordered and disordered domain configurations[12,13] Another consequence of the absence of inversion symmetry is the generation of shift photocurrents under appropriate illumination[14].
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