Dynamic electrical response of vortex polarization in (Pb_0.9Sr_0.1)TiO₃/SrTiO₃ artificial superlattice thin films

Artificial superlattice thin films with alternative Pb_0.9Sr_0.1TiO₃ (PST) and SrTiO₃ layers were fabricated via pulsed laser deposition. The vortex domains were formed by adjusting the unit cell number of the PST layer to be 20. The electrical response measured by time-resolved synchrotron x-ray diffraction with the repeated pulse voltages of a time interval of 1000 μs indicates that the reorientation of dipole moments in the vortex domains is susceptible to the applied electric field and is a reversible process. Although the centrosymmetric vortex domain structure is not considered to exhibit piezoelectricity, an evident change in the out-of-plane lattice constant with the applied electric field was confirmed. The magnitude of the electromechanical response at 600 kV/cm was estimated to be 19 pm/V, which is nearly comparable to the piezoelectric constant d₃₃ of bulk PbTiO₃.