Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
Science. 2012 Apr 6;336(6077):59-61. doi: 10.1126/science.1218693.
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.
铁电材料的特点是存在永久电偶极子，通过施加外部电压可以使其反转，但极化和变形之间的强固有耦合也使所有铁电体具有压电性，从而应用于传感器和大位移致动器。一个较少被探索的特性是挠曲电效应，即极化和应变梯度之间的耦合。我们证明了原子力显微镜的尖端产生的应力梯度可以机械地切换铁电薄膜纳米级体积中的极化。因此，纯机械力可以用作极化控制的动态工具，并可能应用于以机械方式写入和电读取存储位的场景。
