AVS 50th International Symposium
    Nanometer Structures Tuesday Sessions
       Session NS-TuP

Paper NS-TuP18
Second Harmonic Piezoresponse Force Microscopy: A Probe of High Order Ferroelectric Processes

Tuesday, November 4, 2003, 5:30 pm, Room Hall A-C

Session: Poster Session
Presenter: R. Shao, University of Pennsylvania
Authors: R. Shao, University of Pennsylvania
S.V. Kalinin, Oak Ridge National Laboratory
D.A. Bonnell, University of Pennsylvania
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Piezoresponse Force Microscopy (PFM) has been widely accepted as an important technique for imaging ferroelectric domains. The principle of PFM is the detection of the electromechanical response to an ac voltage applied at a tip/surface contact. There are two unresolved issues associated with PFM. The first is the degree of perturbation to ferroelectric domain polarization imposed by the ac voltage. The second is a dilemma involving switching mechanisms during acquisition of the hysteresis loop. To address these issues, we have measured the second harmonic of the electromechanical response to the ac imaging voltage on various ferroelectric materials as a function of both frequency and amplitude of the voltage. A theoretical model has been established that relates the ferroelectric relaxation to the second harmonic response. The approach is extended to an imaging technique, Second Harmonic Piezoresponse Microscopy, that maps the distribution of relaxation times on surfaces by acquiring the spatial distribution of the second harmonic response.