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Register a new userVortex Dynamics, Pinning, and Magic Angles on Moire Patterns
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Added by
Cynthia J. Olson Reichhardt
Publication date
2020
fields
Physics
and research's language is
English
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We examine pinning and dynamics of Abrikosov vortices interacting with pinning centers placed in a moire pattern for varied moire lattice angles. We find a series of magic angles at which the critical current shows a pronounced dip corresponding to lattices in which the vortices can flow along quasi-one-dimensional channels. At these magic angles, the vortices move with a finite Hall angle. Additionally, for some lattice angles there are peaks in the critical current produced when the substrate has a quasiperiodic character that strongly reduces the vortex channeling. Our results should be general to a broad class of particle-like assemblies moving on moire patterns.
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Motivated by the recent achievements in the realization of strongly correlated and topological phases in twisted van der Waals heterostructures, we study the low-energy properties of a twisted bilayer of nodal superconductors. It is demonstrated that the spectrum of the superconducting Dirac quasiparticles close to the gap nodes is strongly renormalized by twisting and can be controlled with magnetic fields, current, or interlayer voltage. In particular, the application of an interlayer current transforms the system into a topological superconductor, opening a topological gap and resulting in a quantized thermal Hall effect with gapless, neutral edge modes. Close to the magic angle, where the Dirac velocity of the quasiparticles is found to vanish, a correlated superconducting state breaking time-reversal symmetry is shown to emerge. Estimates for a number of superconducting materials, such as cuprate, heavy fermion, and organic nodal superconductors, show that twisted bilayers of nodal superconductors can be readily realized with current experimental techniques.
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