Breakdown of\nVolterra’s Elasticity Theory of\nDislocations in Polar Skyrmion Lattices

Emerging polar skyrmion crystals (SkX) have raised much\ninterest\nfor technological applications owing to their nontrivial topologies\nof electric dipoles, quasiparticle-like behaviors, and unique electrical\nresponses. Understanding SkX defects, especially dislocations, is\ncrucial for their unique lattice dynamics and responses; however,\nit still remains elusive. Here, we have not only demonstrated that\na SkX dislocation exhibits an anomalously deformed core structure\nwith over 50% elongation of skyrmions but also discovered that Volterra’s\nelasticity theory of dislocation is broken down in SkX. Our phase-field\nsimulation reveals that these distinct features of SkX dislocation\narise from a rigid to soft quasiparticle transition of skyrmions depending\non the electric field and temperature. In SkX, there exist inherent\nmechanics that mitigate the mismatch by both migration and deformation\nof skyrmions. This work provides novel insights into a new class of\nlattice mechanics and related functionality arising from the unique\nproperties of quasi-particle SkX.