Noncontact Atomic Force Microscopy - Yale School of Engineering ...

P.II-30
Probing Local Bias-Induced Phase Transitions on the Single Defect
Level: from Imaging to Deterministic Mechanisms
N. Balke 1 , S. Jesse 1 , P. Maksymovych 1 , Y.H. Chu 2 , R. Ramesh 2 , S. Choudhury 3 , L.Q.
Chen 3 , and S.V. Kalinin 1
1 Oak Ridge National Laboratory, Oak Ridge, TN 37831
2 Dept. of Physics and Dept. of Mat. Sci. and Eng., University of California, Berkeley, CA
3 Dept. of Mat. Sci. and Eng., Pennsylvania State University, University Park, PA 16802
Force-induced processes such a molecular unfolding spectroscopy and NC-AFM
atomic manipulation now underpin many areas of physics and biology. Here, I discuss
recent progress on probing local bias-induced phase transitions in ferroelectrics and
electrochemical systems. Bias-induced phase transitions are controlled by structural
defects that act both as the local nucleation centers and the pinning centers for moving
domain walls. Future progress necessitates understanding of polarization switching
mechanisms on the single structural or morphological defect level. In this talk, I will
present results on local studies of polarization reversal mechanisms in ferroelectrics [1-2].
The direct imaging of a single nucleation center on the sub-100 nanometer level is
demonstrated [3]. By using switching spectroscopy Piezoresponse Force Microscopy on
systems with engineered defect structures and phase-field modeling, we demonstrate that
deterministic that mesoscopic polarization switching mechanisms on single 1D and 2D
defects can be determined. We develop a framework to link the modeling results to
experimental observations using neural-network based recognition. The future potential
for atomistic studies is discussed. Research was supported by the U.S. Department of
Energy Office of Basic Energy Sciences Division of Scientific User Instruments and was
performed at Oak Ridge National Laboratory which is operated by UT-Battelle, LLC.
Figure 1: (a) Surface topography and (b) SS-PFM nucleation bias map of BiFeO3 24deg (100)
bicrystal grain boundary (GB). Each point in (b) is a hysteresis loop. (c) Ferroelectric switching
properties across the interface.
[1] S.V. Kalinin, B.J. Rodriguez, S. Jesse, Y.H. Chu, T. Zhao, R. Ramesh, E.A. Eliseev, and A.N.
Morozovska, PNAS 104, 20204 (2007).
[2] S. Jesse, B.J. Rodriguez, A.P. Baddorf, I. Vrejoiu, D. Hesse, M. Alexe, E.A. Eliseev, A.N. Morozovska,
and S.V. Kalinin, Nature Materials 7, 209 (2008).
[3] S.V. Kalinin, S. Jesse, B.J. Rodriguez, Y.H. Chu, R. Ramesh, E.A. Eliseev and A.N. Morozovska, Phys.
Rev. Lett. 100, 155703 (2008)
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