The unidirectional dipole wave in (0-10)-oriented SrTiO3/PbTiO3/SrTiO3 films

Dipole waves, characterized by continuous polarization rotation in a sinusoidal function, have great potential for next-generation nanoelectronics. These propagating polarization modulations enable nanoscale periodicity and ultrahigh-density data encoding. In this study, a type of dipole wave structure was predicted in (01¯1)-oriented SrTiO3/PbTiO3/SrTiO3 (STO/PTO/STO) films through phase-field simulations. The structure is characterized by a tendency to align along the [011] direction, which is attributed to the intrinsic in-plane anisotropy resulting from the crystallographic orientation of (01¯1). Upon application of an in-plane electric field parallel to [011], the dipole wave becomes more ordered, forming a unidirectional pattern, described as Pz = A sin[2π(x + x0)/L]. The amplitude (A) of the unidirectional dipole wave is found to be adjustable by the in-plane electric field. Reversible switching between the dipole wave and the trivial domain was achieved under an out-of-plane electric field. These findings establish fundamental principles for designing dipole wave-based nanoelectronic devices.