Effect of external stress on polarization in ferroelectric thin films

The polarization changes caused by applying mechanical stresses to a lead zirconate titanate (PZT) thin film were investigated. Both the remnant and spontaneous polarizations decreased when the PZT film was loaded with tensile stress. For compressive stresses, the remnant polarization increased, but spontaneous polarization did not change. In fatigue with tensile stress state, the polarization decreased earlier than when there was no stress, which depend on whether or not the initial polarization value was high. Conversely, in fatigue with compressive stress, the initial higher remnant polarization value was maintained compared with the polarization in the unstress condition.