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Phase coexistence and electric-field control of toroidal order in oxide superlattices


Abstract: Systems that exhibit phase competition, order parameter coexistence, and emergent order parameter topologies constitute a major part of modern condensed-matter physics. Here, by applying a range of characterization techniques, and simulations, we observe that in PbTiO"3/SrTiO"3 superlattices all of these effects can be found. By exploring superlattice period-, temperature- and field-dependent evolution of these structures, we observe several new features. First, it is possible to engineer phase coexistence mediated by a first-order phase transition between an emergent, low-temperature vortex phase with electric toroidal order and a high-temperature ferroelectric a"1/a"2 phase. At room temperature, the coexisting vortex and ferroelectric phases form a mesoscale, fibre-textured hierarchical superstructure. The vortex phase possesses an axial polarization, set by the net polarization of the surrounding ferroelectric domains, such that it possesses a multi-order-parameter state and belongs to a class of gyrotropic electrotoroidal compounds. Finally, application of electric fields to this mixed-phase system permits interconversion between the vortex and the ferroelectric phases concomitant with order-of-magnitude changes in piezoelectric and nonlinear optical responses. Our findings suggest new cross-coupled functionalities. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.



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 Fuente: NATURE MATERIALS. VOL 16, OCTOBER 2017

Editorial: Nature Publishing Group

 Fecha de publicación: 01/08/2017

Nº de páginas: 9

Tipo de publicación: Artículo de Revista

DOI: 10.1038/NMAT4951

ISSN: 1476-1122,1476-4660

Url de la publicación: https://doi.org/10.1038/NMAT4951

Autores/as

DAMODARAN, A, R.
CLARKSON, J. D.
HONG, Z.
YADAV, A. K.
NELSON, Z. T.
MCCARTER, M. R.
PARK, K. D.
KRAVTSOV, V.