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

A. R. Damodaran, J. D. Clarkson, Z. Hong, H. Liu, A. K. Yadav, C. T. Nelson, S. L. Hsu, M. R. McCarter, K. D. Park, V. Kravtsov, A. Farhan, Y. Dong, Z. Cai, H. Zhou, P. Aguado-Puente, P. Garcia-Fernandez, J. Iniguez, J. Junquera, A. Scholl, M. B. RaschkeL. Q. Chen, D. D. Fong, R. Ramesh, L. W. Martin

Research output: Contribution to journalArticlepeer-review

66 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)1003-1009
Number of pages7
JournalNature Materials
Volume16
Issue number10
DOIs
StatePublished - Oct 1 2017
Externally publishedYes

Bibliographical note

Funding Information:
1003 1009 10.1038/nmat4951 EN A. R. Damodaran Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA http://orcid.org/0000-0002-2094-9956 J. D. Clarkson Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA Z. Hong Department of Materials Science and Engineering, Pennsylvania State University, State College, Pennsylvania 16802, USA H. Liu Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA A. K. Yadav Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA School of Electrical Engineering and Computer Science, UC Berkeley, Berkeley, California 94720, USA http://orcid.org/0000-0001-5088-6506 C. T. Nelson Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA S.-L. Hsu Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA M. R. McCarter Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA K.-D. Park Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder, Boulder, Colorado 80309, USA V. Kravtsov Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder, Boulder, Colorado 80309, USA http://orcid.org/0000-0002-3555-1027 A. Farhan Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA http://orcid.org/0000-0002-2384-2249 Y. Dong Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA Z. Cai X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA H. Zhou X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA P. Aguado-Puente Centro de Física de Materiales, Universidad del País Vasco, 20018 San Sebastián, Spain Donostia International Physics Center, 20018 San Sebastián, Spain P. García-Fernández Departmento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Cantabria Campus Internacional, avenida de los Castros s/n, 39005 Santander, Spain J. Íñiguez Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST), 5 avenue des Hauts-Fourneaux, L-4362 Esch/Alzette, Luxembourg J. Junquera Departmento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Cantabria Campus Internacional, avenida de los Castros s/n, 39005 Santander, Spain http://orcid.org/0000-0002-9957-8982 A. Scholl Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA M. B. Raschke Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder, Boulder, Colorado 80309, USA L.-Q. Chen Department of Materials Science and Engineering, Pennsylvania State University, State College, Pennsylvania 16802, USA D. D. Fong Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA R. Ramesh Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA L. W. Martin Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA http://orcid.org/0000-0003-1889-2513 nmat4951 10.1038/nmat4951 2016 12 17 2017 06 28 2017 August 07 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.

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