Research Papers in Physics and Astronomy


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Published in Science vol. 336, no. 6077 (April 6, 2012), pp. 59–61; doi: 10.1126/science.1218693 Online at 336/6077/59.abstract Copyright © 2012 American Association for the Advancement of Science. Used by permission.


Ferroelectric materials are characterized by a permanent electric dipole that can be reversed through the application of an external voltage, but a strong intrinsic coupling between polarization and deformation also causes all ferroelectrics to be piezoelectric, leading to applications in sensors and high-displacement actuators. A less explored property is flexoelectricity, the coupling between polarization and a strain gradient. We demonstrate that the stress gradient generated by the tip of an atomic force microscope can mechanically switch the polarization in the nanoscale volume of a ferroelectric film. Pure mechanical force can therefore be used as a dynamic tool for polarization control and may enable applications in which memory bits are written mechanically and read electrically.

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