One-dimensional Kronig–Penney superlattices at the LaAlO3/SrTiO3 interface

The paradigm of electrons interacting with a periodic lattice potential is central to solid-state physics. Semiconductor heterostructures and ultracold neutral atomic lattices capture many the essential properties 1D electronic systems. However, fully one-dimensional superlattices are highly challenging fabricate in solid state due inherently small length scales involved. Conductive atomic-force microscope (c-AFM) lithography has recently been demonstrated create ballistic few-mode electron waveguides quantized conductance strongly attractive electron-electron interactions. Here we show that artificial Kronig-Penney-like superlattice potentials can be imposed on such waveguides, introducing new spacing made comparable mean separation between electrons. "fractures" subbands into manifold magnetically-tunable fractional (in units $e^2/h$). lowest $G=2e^2/h$ plateau, associated transport spin-singlet pairs, stable against de-pairing up highest magnetic fields explored ($|B|=16$ T). A model system suggests an engineered spin-orbit interaction contributes enhanced pairing observed devices. These findings represent important advance ability design families quantum materials emergent properties, mark milestone development simulation platform.