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Ferroelectric Self‐Poling, Switching, and Monoclinic Domain Configuration in BiFeO 3 Thin Films
Author(s) -
Beekman C.,
Siemons W.,
Chi M.,
Balke N.,
Howe J. Y.,
Ward T. Z.,
Maksymovych P.,
Budai J. D.,
Tischler J. Z.,
Xu R.,
Liu W.,
Christen H. M.
Publication year - 2016
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201600468
Subject(s) - poling , monoclinic crystal system , ferroelectricity , materials science , polarization (electrochemistry) , multiferroics , crystallography , epitaxy , condensed matter physics , thin film , perovskite (structure) , optoelectronics , crystal structure , nanotechnology , dielectric , physics , chemistry , layer (electronics)
Self‐poling of ferroelectric films, i.e., a preferred, uniform direction of the ferroelectric polarization in as‐grown samples is often observed yet poorly understood despite its importance for device applications. The multiferroic perovskite BiFeO 3 , which crystallizes in two distinct structural polymorphs depending on applied epitaxial strain, is well known to exhibit self‐poling. This study investigates the effect of self‐poling on the monoclinic domain configuration and the switching properties of the two polymorphs of BiFeO 3 ( R ′ and T ′) in thin films grown on LaAlO 3 substrates with slightly different La 0.3 Sr 0.7 MnO 3 buffer layers. This study shows that the polarization state formed during the growth acts as “imprint” on the polarization and that switching the polarization away from this self‐poled direction can only be done at the expense of the sample's monoclinic domain configuration. The observed reduction of the monoclinic domain size is largely reversible; hence, the domain size is restored when the polarization is switched back to its original orientation. This is a direct consequence of the growth taking place in the polar phase (below T c ). Switching the polarization away from the preferred configuration, in which defects and domain patterns synergistically minimize the system's energy, leads to a domain state with smaller (and more highly strained and distorted) monoclinic domains.