Abstract
The coupling between ionic degrees of freedom and ferroelectricity has received renewed attention in recent years, given that surface electrochemical processes have been shown to be intrinsically linked to ferroelectric phase stability in ultrathin ferroelectric films. However, the coupling between bulk ionic transport and local polarization switching has received less attention, as typically the bulk ionic mobilities are low for common ferroelectrics at room temperature. Here, we use the coupled band-excitation method in conjunction with site-correlated time-of-flight secondary ion mass spectrometry, to determine the coupling between ferroelectric switching and ionic motion in single crystal KTiOPO4. The local scanning probe measurements indicate a substantial softening, as determined by resonant frequency changes, during reversal of polarization along one direction. These changes are correlated with the mass spectrometry measurements, showing a polarization-dependent accumulation of K ions at the polar surfaces, thus corroborating their role in the screening process. These studies shed light on the interplay between ionic dynamics and bulk ferroelectric switching and have implications for studies on domain wall conductivity, chemical switching, and bulk and surface-screening phenomena.
Original language | English |
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Pages (from-to) | 32298-32303 |
Number of pages | 6 |
Journal | ACS Applied Materials and Interfaces |
Volume | 10 |
Issue number | 38 |
DOIs | |
State | Published - Sep 26 2018 |
Funding
A portion of this work was sponsored by the U.S. Department of Energy (DOE), Office of Science, Materials Sciences and Engineering Division (R.K.V. and S.V.K.). Research was conducted at the Center for Nanophase Materials Sciences (A.I., S.J., O.S.O.), which is a DOE Office of Science User Facility, and using instrumentation within ORNL’s Materials Characterization Core provided by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. G.L. and C.C. acknowledge support and access to the Center for Nanophase Materials Sciences through the proposal CNMS2017-066. G.L. and C.C. also acknowledge support from the Swedish Foundation for Strategic Research and the Swedish Research Council (VR) through its Linné Center for Advanced Optics and Photonics (ADOPT).
Keywords
- KTiOPO
- ferroelectric switching
- ferroelectricity
- ionic conductor
- ionic transport
- surface-screening