The chirality of polar skyrmion bubbles is critical to their topological identities and potential applications. Although previous phase-field models could simulate polar skyrmion bubbles, the Bloch-type feature key to the chirality is not produced. Here, we introduce an extended phase-field model with biquadratic coupling between polarization and its gradient. Taking the ${\mathrm{SrTiO}}_3$/${\mathrm{PbTiO}}_3$/${\mathrm{SrTiO}}_3$ heterostructure as an example, it is found that with the increase of the coupling strength, a transition occurs from achiral to chiral skyrmion bubbles, and ultimately to mixed-chiral bubbles with zero net chirality. However, the chirality of the skyrmion bubbles is random and external electric field and temperature could not result in a uniform chirality. Notably, the homochiral vortex tubes would transform into the skyrmion bubbles with uniform chirality under the electric field, while achiral precursors lead to random chirality. These results provided a theoretical framework and practical strategies for chirality engineering in polar skyrmions.

Close

PrevNext

View figure in article

• Ferroelectricity
• Skyrmions
• Chiral symmetry
• Phase-field modeling