Translational covariance of flexoelectricity at ferroelectric domain walls
Diéguez, Oswaldo (Institut Català de Nanociència i Nanotecnologia)
Stengel, Massimiliano (Institut de Ciència de Materials de Barcelona)

Date:	2022
Abstract:	Macroscopic descriptions of ferroelectrics have an obvious appeal in terms of efficiency and physical intuition. Their predictive power, however, has often been thwarted by the lack of a systematic procedure to extract the relevant materials parameters from the microscopics. Here we address this limitation by establishing an unambiguous two-way mapping between spatially inhomogeneous fields and discrete lattice modes. This yields a natural treatment of gradient couplings in the macroscopic regime via a long-wavelength expansion of the crystal Hamiltonian. Our analysis reveals an inherent arbitrariness in both the flexoelectric and polarization gradient coefficients, which we ascribe to a translational freedom in the definition of the polar distortion pattern. Remarkably, such arbitrariness cancels out in all physically measurable properties (relaxed atomic structure and energetics) derived from the model, pointing to a generalized translational covariance in the continuum description of inhomogeneous ferroelectric structures. We demonstrate our claims with extensive numerical tests on 180° domain walls in common ferroelectric perovskites, finding excellent agreement between the continuum model and direct first-principles calculations.
Grants:	European Commission 724529 Ministerio de Economía y Competitividad PID2019-108573-GB-C22 Ministerio de Economía y Competitividad CEX2019-000917-S Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-1506
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Discrete lattices ; Ferroelectric domains ; Flexoelectricity ; Inhomogeneous fields ; Lattice modes ; Materials parameters ; Natural treatment ; Predictive power ; Spatially inhomogeneous ; Two ways
Published in:	Physical Review, Vol. 12, issue 3 (Jul.-Sep. 2022) , art. 31002, ISSN 2160-3308

DOI: 10.1103/PhysRevX.12.031002

19 p, 644.7 KB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Catalan Institute of Nanoscience and Nanotechnology (ICN2)
Articles > Research articles
Articles > Published articles