Piezoresponse Force Microscopy with Asylum Research Atomic Force Microscopes - Asylum Research - #1

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1 Electromechanical coupling is one of the fundamental mechanisms underlying the functionality of many materials. These include inorganic macro-molecular materials, such as piezo- and ferroelectrics, as well as many biological systems. This application note discusses the background, techniques, problems and solutions to piezoresponse force microscopy (PFM) measurements using the MFP-3D™ AFM and Cypher™ AFM from Asylum Research. Background The functionality of systems ranging from nonvolatile computer memories and micro electromechanical systems to electromotor proteins and cellular membranes are ultimately based on the intricate coupling between electrical and mechanical phenomena.1 The applications of electromechanically active materials include sonar, ultrasonic and medical imaging, sensors, actuators, and energy harvesting technologies. In the realm of electronic devices, piezoelectrics are used as components of RF filters and surface-acoustic wave (SAW) devices. 2 The ability of ferroelectric materials to switch polarization orientation – and maintain polarization state in a zero electric field – has lead to emergence of concepts of non-volatile ferroelectric memories and data storage devices.3 Electromechanical coupling is the basis of many biological systems, from hearing to cardiac activity. The future will undoubtedly see the emergence, first in research labs and later in industrial settings, of the broad arrays of piezoelectric, biological and molecularbased electromechanical systems. Progress along this path requires the ability to image and quantify electromechanical functionalities on the nanometer and molecular scale (Figures 1 and 2). Areas such as nanomechanics and single-molecule imaging and force measurements have been enabled by the emergence of microscopic tools such as nanoindentation and protein unfolding spectroscopy. Figure 1: PFM amplitude channel overlaid on AFM height (top) and phase image overlaid on height (bottom) of lead zirconium titanate (PZT), 20ìm scan. PFM A P P N O T E 1 0 Roger Proksch, Asylum Research and Sergei Kalinin, Center for Nanophase Materials Sciences (CNMS) at Oak Ridge National Laboratory Piezoresponse Force Microscopy with Asylum Research AFMs