AVS 53rd International Symposium
    Nanometer-scale Science and Technology Tuesday Sessions
       Session NS1-TuM

Paper NS1-TuM9
Local Probing of Polarization Switching in Low-Dimensional Ferroelectrics

Tuesday, November 14, 2006, 10:40 am, Room 2016

Session: Nanoscale Structures and Characterization II
Presenter: S. Jesse, Oak Ridge National Laboratory
Authors: S. Jesse, Oak Ridge National Laboratory
B.J. Rodriguez, Oak Ridge National Laboratory
S.V. Kalinin, Oak Ridge National Laboratory
E.A. Eliseev, National Academy of Science of Ukraine
A.N. Morozovska, National Academy of Science of Ukraine
Correspondent: Click to Email
Quantitative measurements of local switching characteristics and the relationship between switching behavior and defects on the nanoscale are crucial for the application of ferroelectric materials as non-volatile memories and ultra high density data storage. Switching Spectroscopy Piezoresponse Force Microscopy (SS-PFM) is developed as a quantitative tool for real-space mapping of switching properties of ferroelectrics, including imprint, coercive bias, remanent and saturation responses, and work of switching. In SS-PFM, multiple electromechanical hysteresis curves are collected at each point in an image to extract maps of parameters describing the switching behavior. The nucleation and growth of a single domain occurs under a sharp tip and hysteresis follows the development of a domain at a given location. The theory for hysteresis loop formation in the thermodynamic and kinetic limits is developed to relate SS-PFM data with local material properties and polarization dynamics. Several examples of switching behavior in low dimensional ferroelectrics are presented including (a) pinning at grain boundaries in polycrystalline PZT, (b) non-uniform work of switching in ferroelectric nanodots and (c) switching in the vicinity of topographic defects. In nanodots, the non-uniform work of switching was imaged with ~10 nm resolution within 50 nm ferroelectric nanoparticles. "Abnormal" hysteresis loops were observed in the vicinity of topographic defects in ferroelectric thin films and PZT ceramics and attributed to the interaction of the nascent domain with the strain field of the defect. Future prospects for SS-PFM as a tool for probing ferroelectricity in low-dimensional systems and ferroelectric-based device characterization are discussed.