Scanning probe microscopy observation of nanoscale domain switching in sol-gel PbTiO₃ thin films

In this paper, we present direct observations of local domain switching in the individual grains of 300nm thick sol-gel PbTiO₃ thin films using a piezo-response SPM. It is revealed that almost no domain switching occurs in the c-domain region at 4V, and partially switching takes place at 6V. The switched domain expends the whole grain rapidly by further increasing the bias. The a-domain cannot be reoriented even at the bias up to 10V. High tetragonality of PbTiO₃ is believed to induce great strain to suppress the reorientation of a-domains. The polarization contrast difference at various bias voltages may originate from the non-switchable polarization near the bottom electrode and the partially switched domain.