title: Multiferroic Dislocations in Ferroelectric PbTiO3.
abstract: Ultrathin multiferroics with coupled ferroelectric and ferromagnetic order parameters hold promise for novel technological paradigms, such as extremely thin magnetoelectric memories. However, these ferroic orders and their functions inevitably disappear below a fundamental size limit of several nanometers. Herein, we propose a novel design strategy for nanoscale multiferroics smaller than the critical size limit by engineering the dislocations in nonmagnetic ferroelectrics, even though these lattice defects are generally believed to be detrimental. First-principles calculations demonstrate that Ti-rich PbTiO3dislocations exhibit magnetism due to the local nonstoichiometry intrinsic to the core structures. Highly localized spin moments in conjunction with the host ferroelectricity enable these dislocations to function as atomic-scale multiferroic channels with a pronounced magnetoelectric effect that are associated with the antiferromagnetic-ferromagnetic-nonmagnetic phase transitions in response to polarization switching. The present results thus suggest a new field of dislocation (or defect) engineering for the fabrication of ultrathin magnetoelectric multiferroics and ultrahigh density electronic devices.
authors.affiliation: Department of Mechanical Engineering and Science, Kyoto University , Nishikyo-ku, Kyoto 615-8540, Japan.
authors.forename: Takahiro
authors.identifier: 0000-0002-8404-5673
authors.initials: T
authors.lastname: Shimada
authors.affiliation: Department of Mechanical Engineering and Science, Kyoto University , Nishikyo-ku, Kyoto 615-8540, Japan.
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.affiliation: Department of Mechanical Engineering and Science, Kyoto University , Nishikyo-ku, Kyoto 615-8540, Japan.
authors.forename: Yasumitsu
authors.initials: Y
authors.lastname: Araki
authors.affiliation: Department of Engineering Mechanics, School of Aeronautics and Astronautics, Zhejiang University , Hangzhou 310027, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Mechanical Engineering and Science, Kyoto University , Nishikyo-ku, Kyoto 615-8540, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kitamura
keywords: Multiferroics; dislocations; ferroelectrics; magnetoelectric effect; nonstoichiometry