title: Ferroelectric Metal in Tetragonal BiCoO3/BiFeO3 Bilayers and Its Electric Field Effect.
abstract: By first-principles calculations we investigate the electronic structure of tetragonal BiCoO3/BiFeO3 bilayers with different terminations. The multiferroic insulator BiCoO3 and BiFeO3 transform into metal in all of three models. Particularly, energetically favored model CoO2-BiO exhibits ferroelectric metallic properties, and external electric field enhances the ferroelectric displacements significantly. The metallic character is mainly associated to eg electrons, while t2g electrons are responsible for ferroelectric properties. Moreover, the strong hybridization between eg and O p electrons around Fermi level provides conditions to the coexistence of ferroelectric and metallic properties. These special behaviors of electrons are influenced by the interfacial electronic reconstruction with formed Bi-O electrovalent bond, which breaks OA-Fe/Co-OB coupling partially. Besides, the external electric field reverses spin polarization of Fe/Co ions efficiently, even reaching 100%.
authors.affiliation: Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, Faculty of Science, Tianjin University, Tianjin, 300072, China.
authors.forename: Li
authors.initials: L
authors.lastname: Yin
authors.affiliation: Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, Faculty of Science, Tianjin University, Tianjin, 300072, China.
authors.forename: Wenbo
authors.initials: W
authors.lastname: Mi
authors.affiliation: Tianjin Key Laboratory of Film Electronic &Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384, China.
authors.forename: Xiaocha
authors.initials: X
authors.lastname: Wang
references.citation: Phys Rev Lett. 2014 Oct 31;113(18):186401
references.pmid: 25396383
references.citation: Proc Natl Acad Sci U S A. 2012 Jun 19;109(25):9710-5
references.pmid: 22647612
references.citation: Nature. 2003 Nov 6;426(6962):55-8
references.pmid: 14603314
references.citation: Science. 2006 Jun 9;312(5779):1481-2
references.pmid: 16763137
references.citation: Nat Mater. 2012 Mar;11(3):195-8
references.pmid: 22266467
references.citation: Dalton Trans. 2015 Jun 21;44(23):10882-7
references.pmid: 25974365
references.citation: Adv Mater. 2013 May 7;25(17):2497-504
references.pmid: 23505214
references.citation: Nat Mater. 2007 Jan;6(1):21-9
references.pmid: 17199122
references.citation: Science. 2005 Jul 15;309(5733):391-2
references.pmid: 16020720
references.citation: Nat Mater. 2007 Jan;6(1):13-20
references.pmid: 17199121
references.citation: Inorg Chem. 2008 Aug 18;47(16):7355-9
references.pmid: 18642895
references.citation: Science. 2003 Mar 14;299(5613):1719-22
references.pmid: 12637741
references.citation: Nat Mater. 2013 Nov;12(11):1024-7
references.pmid: 24056805
references.citation: Adv Mater. 2011 Jul 26;23(28):3170-5
references.pmid: 21608053
references.citation: J Chem Phys. 2007 Apr 21;126(15):154708
references.pmid: 17461660
references.citation: Phys Rev Lett. 2010 Jul 9;105(2):027201
references.pmid: 20867733
references.citation: Nature. 2004 Jan 29;427(6973):423-6
references.pmid: 14749825
references.citation: Nature. 2006 Aug 17;442(7104):759-65
references.pmid: 16915279
references.citation: Phys Rev Lett. 2015 Aug 21;115(8):087202
references.pmid: 26340204
references.citation: Phys Rev Lett. 2008 Jun 6;100(22):227602
references.pmid: 18643458
references.citation: Science. 2009 Nov 13;326(5955):977-80
references.pmid: 19965507
references.citation: ACS Nano. 2013 Jun 25;7(6):5385-90
references.pmid: 23647323
references.citation: Nat Mater. 2012 Jan 24;11(2):103-13
references.pmid: 22270825
references.citation: Phys Rev Lett. 2011 Sep 30;107(14):147602
references.pmid: 22107234
references.citation: J Phys Condens Matter. 2006 Feb 15;18(6):L97-L105
references.pmid: 21697555
references.citation: Nature. 2004 May 27;429(6990):392-5
references.pmid: 15164057
references.citation: Science. 2005 Feb 25;307(5713):1203; author reply 1203
references.pmid: 15731427
references.citation: Phys Rev Lett. 2011 Jul 29;107(5):057601
references.pmid: 21867098
references.citation: Nat Mater. 2010 Sep;9(9):756-61
references.pmid: 20657590