Piezoresponse Force Microscope
Ferroelectric material generates an electric charge when pressure is applied. Also, it will expand and contract when a voltage is applied. In Piezoresponse Force Microscope (PFM), a conductive cantilever is used to apply a voltage to a local region of a ferroelectric material, and distortion caused by the piezoelectric effect of the ferroelectric material is detected as a deflection of the cantilever and imaged (Gruverman in Appl Phys Lett 69:3191–3193, 1996 ). In the measurement, the polarized state of the sample is measured with respect to the AC voltage applied between the sample and the probe by whether the relationship between expansion and contraction of the sample strain is in-phase or reversed (Fig. 80.1). Piezoelectric response of ferroelectric material of nm order can be detected. PFM is a useful technique for local polarization/phase transition of ferroelectric material, observation of domain boundary, and so on.