Ferroelastic-Domain-Assisted Mechanical Switching of Ferroelectric Domains in Pb(Zr,Ti)O₃ Thin Films

A recent breakthrough in mechanical polarization switching provides a valuable handle to achieve nanoscale ferroelectric domain control. This flexoelectric switching is usually observed in ultrathin films (≈10 nm or less in thickness), where a large strain gradient is possible. However, from the point of view of device applications, it will be more attractive to achieve mechanical domain switching in thicker films. Here, it is experimentally demonstrated that by introducing ferroelastic a-domains in PbZr_0.1Ti_0.9O₃ films the potential barrier against 180° c-domain switching can be greatly decreased, enabling mechanical ferroelectric domain switching in 50 nm thick films by applying a loading force from an atomic force microscope tip. Moreover, these a-domains are stable in the c-domain matrix without further mechanical stressing. This makes it possible to create nanoscale domain wall circuitry. These results shed light on the mechanism of domain switching in ferroelectric thin films and may facilitate the design of mechanically controlled novel ferroelectric devices.