IN-SITU STRAIN TUNING DURING ADVANCED AFM CHARACTERIZATION

The strong electro-mechanical coupling in ferroelecrtics facilitates these materials for a broad range of technologies, varying from radio-frequency filters for cellular communication to actuators and sensors. Piezoresponse force microscopy (PFM) is a spin-off method of atomic force microscopy (AFM), designed to image the polarization distribution in ferroelectrics at the nanometer scale. Although PFM has advanced the understanding of the electrical properties of ferroelectrics, understanding the role of mechanical strain has remained a challenge, mainly due to the limited availability of experimental techniques for controlling and tuning strain externally. Hence, remaining the unique potential of the electro-mechanical coupling in ferroelectrics unfulfilled.

Here, we demonstrate in-situ strain control during advanced AFM characterization. Dynamic strain control was obtained with a specially designed 4-point-bending stage, in which a large area below the tip assumes a constant strain. Static control was demonstrated through bent stages with a constant-angle. The strain control system allowed us to understand the role of strain on the ferroelectric properties with the aid of PFM characterization. The demonstrated system is compatible with high-temperature imaging capabilities, recently developed in our group. The generic system demonstrated here for high-resolution PFM characterization is applicable for general AFM characterization modes, expanding the borders of atomic force microscopy.