Dresden 2017 – scientific programme

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MA: Fachverband Magnetismus

MA 25: Ferroics - Domains, Domain Walls and Skyrmions I

MA 25.12: Talk

Tuesday, March 21, 2017, 13:00–13:15, WIL B321

Enhancement of local photovoltaic current at ferroelectric domain walls in BiFeO₃ — •Ming-Min Yang and Marin Alexe — Department of Physics, University of Warwick, Coventry, UK

Domain walls, which are intrinsically two-dimensional nano-objects exhibiting nontrivial electronic and magnetic behaviors, have been proven to play a crucial role in photovoltaic properties of ferroelectrics. Despite this recognition, the electronic properties of domain walls under illumination until now have been accessible only to macroscopic studies and their effects upon the conduction of photovoltaic current still remain elusive. The lack of understanding hinders the developing of nanoscale devices based on ferroelectric domain walls. Here, we directly characterize the local photovoltaic and photoconductive properties of 71 degree domain walls on BiFeO₃ thin films with a nanoscale resolution. Local photovoltaic current, proven to be driven by the bulk photovoltaic effect, has been probed over the whole illuminated surface by using a specially designed photoelectric atomic force microscopy and found to be significantly enhanced at domain walls. Additionally, spatially resolved photoconductive current distribution reveals a higher density of excited carriers at domain walls in comparison with domains. Our measurements demonstrate that domain wall enhanced photovoltaic current originates from its high conduction rather than the internal electric field. This photoconduction facilitated local photovoltaic current is likely to be a universal property of topological defects in ferroelectric semiconductors.