Advanced Lithography of Complex Ferroic Topological Structures

Arbitrary polar rotation in oxide perovskites⁶ and spontaneous flux closure domain formation within a single material is rarely observed due to the high anisotropy energy inherent to ferroelectrics.⁷ Purely physical rotation of polarization has only been achieved by flexoelectricity⁸, i.e., structural strain gradients, taking advantage of the coupling of ferroelectric and ferroelastic properties or depolarization field engineering in thin film heterostructures, which combine ferroelectric and dielectric layers leading to curling behaviour of polarization and the creation of vortices-like structures. Non-trivial topological structures have been discovered in confined ferroelectric layers within artificially engineered superlattices, altogether providing promising alternatives for nanoelectronic devices based on negative capacitance, or fast broadband communications required for the 6G era thanks to intrinsic sub-THz resonances. However, examples on the manipulation of these topological structures is scarce and only few of them have been created via electric field litography so far. Here, we will show advanced ferroelectric lithography methodes that will allow the creation of complex topological structures such as skyrmions, vortices and flux closures on demand.