Conductivity of twin-domain-wall/surface junctions in ferroelastics: Interplay of deformation potential, octahedral rotations, improper ferroelectricity, and flexoelectric coupling

Phys. Rev. B 86, 085416 – Published 8 August 2012
Eugene A. Eliseev, Anna N. Morozovska, Yijia Gu, Albina Y. Borisevich, Long-Qing Chen, Venkatraman Gopalan, and Sergei V. Kalinin

Abstract

Electronic and structural phenomena at the twin-domain-wall/surface junctions in the ferroelastic materials are analyzed. Carriers accumulation caused by the strain-induced band structure changes originated via the deformation potential mechanism, structural order parameter gradient, rotostriction, and flexoelectric coupling is explored. Approximate analytical results show that inhomogeneous elastic strains, which exist in the vicinity of the twin-domain-wall/surface junctions due to the rotostriction coupling, decrease the local band gap via the deformation potential and flexoelectric coupling mechanisms. This is the direct mechanism of the twin-wall static conductivity in ferroelastics and, by extension, in multiferroics and ferroelectrics. On the other hand, flexoelectric and rotostriction coupling leads to the appearance of the improper polarization and electric fields proportional to the structural order parameter gradient in the vicinity of the twin-domain-wall/surface junctions. The “flexoroto” fields leading to the carrier accumulation are considered as an indirect mechanism of the twin-wall conductivity. Comparison of the direct and indirect mechanisms illustrates a complex range of phenomena directly responsible for domain-wall static conductivity in materials with multiple order parameters.

DOI: http://dx.doi.org/10.1103/PhysRevB.86.085416

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  • Received 20 May 2012
  • Published 8 August 2012

©2012 American Physical Society

Authors & Affiliations

Eugene A. Eliseev1, Anna N. Morozovska2,*, Yijia Gu3, Albina Y. Borisevich4, Long-Qing Chen3, Venkatraman Gopalan3, and Sergei V. Kalinin4

  • 1Institute for Problems of Materials Science, National Academy of Science of Ukraine, 3, Krjijanovskogo, 03142 Kiev, Ukraine
  • 2Institute of Physics, National Academy of Science of Ukraine, 46, pr. Nauki, 03028 Kiev, Ukraine
  • 3Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA
  • 4Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA

  • *Corresponding author: morozo@i.com.ua

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