Topological bubble domain engineering for high strain response

Enhancing the piezoelectric or strain response of materials through nanodomain engineering has proven to be highly effective. Here, we demonstrate that topological bubble domains (BDs) can be induced in Bi_0.5Na_0.5TiO₃ (BNT)-based thin films via lattice distortions. We establish a positive correlation between the density of BDs, macroscopic polarization, and strain response. The BDs in BNT-based thin films leads to a remarkable enhancement in the strain response, reaching ~400% of the virgin state. This enhancement arises from the lower energy barriers for dipole flipping and domain switching associated with BDs, in comparison to conventional domain structures. Under an applied electric field, the rotation of polarized BDs, combined with a reduction in dipole flux due to the articulated rotation between BDs and surrounding domains, further amplifies the strain response. These findings advance our understanding of BDs in electromechanical materials and provide theoretical guidance for designing high-performance piezoelectrics with polar topologies.