title: Deterministic arbitrary switching of polarization in a ferroelectric thin film.
abstract: Ferroelectrics have been used as memory storage devices, with an upper bound on the total possible memory levels generally dictated by the number of degenerate states allowed by the symmetry of the ferroelectric phase. Here, we introduce a new concept for storage wherein the polarization can be rotated arbitrarily, effectively decoupling it from the crystallographic symmetry of the ferroelectric phase on the mesoscale. By using a Bi5Ti3FeO15-CoFe2O4 film and via Band-Excitation Piezoresponse Force Microscopy, we show the ability to arbitrarily rotate polarization, create a spectrum of switched states, and suggest the reason for polarization rotation is an abundance of sub-50 nm nanodomains. Transmission electron microscopy-based strain mapping confirms significant local strain undulations imparted on the matrix by the CoFe2O4 inclusions, which causes significant local disorder. These experiments point to controlled tuning of polarization rotation in a standard ferroelectric, and hence the potential to greatly extend the attainable densities for ferroelectric memories.
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: R K
authors.initials: RK
authors.lastname: Vasudevan
authors.affiliation: 1] Department of Applied Chemistry, School of Engineering, Tohoku University 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan [2] Materials and Structures Laboratory, Tokyo Institute of Technology, Midori-ku, 4259 Nagatsuta, Yokohama 226-8503, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: School of Materials Science and Engineering, University of New South Wales, Kensington, New South Wales 2052, Australia.
authors.forename: Xuan
authors.initials: X
authors.lastname: Cheng
authors.affiliation: 1] Materials and Structures Laboratory, Tokyo Institute of Technology, Midori-ku, 4259 Nagatsuta, Yokohama 226-8503, Japan [2] School of Materials Science and Engineering, University of New South Wales, Kensington, New South Wales 2052, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Imai
authors.affiliation: Department of Applied Chemistry, School of Engineering, Tohoku University 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Maruyama
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: H L
authors.initials: HL
authors.lastname: Xin
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Okatan
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: S
authors.initials: S
authors.lastname: Jesse
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: S V
authors.initials: SV
authors.lastname: Kalinin
authors.affiliation: School of Materials Science and Engineering, University of New South Wales, Kensington, New South Wales 2052, Australia.
authors.forename: V
authors.initials: V
authors.lastname: Nagarajan