Nanoscale frictional imaging of ferroelectric domains.

Nanoscale control of electromechanical coupling transforms frictional information into a direct probe of ferroelectric polarization. Here, we show that an asymmetric friction response induced by high contact forces applied with a scanning probe microscopy tip enables spatially resolved visualization of ferroelectric polarization in thin films and single crystals. In agreement with multifield coupled continuum mechanical simulations, our results reveal that this friction asymmetry results from flexoelectrically induced polarization either competing with or enhancing the ferroelectric polarization, thus giving mechanical information on its orientation. This technique, which we term polarization-derived friction microscopy, allows rapid, low-cost, and voltage-free imaging of ferroelectric domains, thereby minimizing electrostatic measurement artifacts and achieving high scan rates beyond 14 frames per second. Our work opens broad opportunities for high-throughput functional imaging of surfaces with extensive potential applications such as voltage-free data acquisition and studies of polarization dynamics in complex environments.