title: Chemical State Evolution in Ferroelectric Films during Tip-Induced Polarization and Electroresistive Switching.
abstract: Domain formation and ferroelectric switching is fundamentally inseparable from polarization screening, which on free surfaces can be realized via band bending and ionic adsorption. In the latter case, polarization switching is intrinsically coupled to the surface electrochemical phenomena, and the electrochemical stage can control kinetics and induce long-range interactions. However, despite extensive evidence toward the critical role of surface electrochemistry, little is known about the nature of the associated processes. Here we combine SPM tip induce polarization switching and secondary ion mass spectrometry to explore the evolution of chemical state of ferroelectric during switching. Surprisingly, we find that even pristine surfaces contain ions (e.g., Cl-) that are not anticipated based on chemistry of the system and processing. In the ferroelectric switching regime, we find surprising changes in surface chemistry, including redistribution of base cations. At higher voltages in the electroforming regime significant surface deformation was observed and associated with a strong ion intermixing.
authors.affiliation: The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, United States.|Institute for Functional Imaging of Materials, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, United States.
authors.forename: Anton V
authors.initials: AV
authors.lastname: Ievlev
authors.affiliation: The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, United States.|Institute for Functional Imaging of Materials, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, United States.
authors.forename: Petro
authors.initials: P
authors.lastname: Maksymovych
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.|Department of Materials, ETH Zurich , Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland.
authors.forename: Morgan
authors.initials: M
authors.lastname: Trassin
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.|School of Materials Science and Engineering, University of New South Wales , Sydney New South Wales 2052, Australia.
authors.forename: Jan
authors.initials: J
authors.lastname: Seidel
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
authors.forename: Ramamoorthy
authors.initials: R
authors.lastname: Ramesh
authors.affiliation: The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, United States.|Institute for Functional Imaging of Materials, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, United States.
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Kalinin
authors.affiliation: The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, United States.|Institute for Functional Imaging of Materials, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, United States.
authors.forename: Olga S
authors.initials: OS
authors.lastname: Ovchinnikova
keywords: atomic force microscopy; chemical phenomena; ferroelectric thin film; ion intermixing; polarization switching; time-of-flight secondary ion mass spectrometry