Moiré engineering and novel electronic transport at oxide interfaces*

Moiré engineering has recently emerged as an effective approach to control quantum phenomena in condensed matter systems. Here we demonstrate electronic moiré patterns in films of a prototypical magnetoresistive oxide, La_0.67Sr_0.33MnO₃, epitaxially grown on LaAlO₃ substrates. Microscopic moiré profiles of both the electronic conductivity and ferromagnetism are observed, which can be attributed to the coexistence and interaction of two distinct incommensurate patterns of strain modulation. Our work provides a potential route to achieving spatially patterned electronic textures on demand in strained epitaxial materials.

On the other hand, the states inside superconducting gaps in tunneling spectra have been revealed to be associated with a spectrum of nontrivial effects, such as Majorana bound states. Here we further present our recent progresses in the tunneling measurements involving oxide heterostructures, and the central findings include: 1) Zero-bias conductance peaks effectively tuned by gating-controlled Rashba spin-orbit coupling in the hybrid junctions composed of the conducting LaAlO₃/SrTiO₃ interface and superconducting Nb; 2) In-gap Andreev bound states observed for the hybrid junctions involving the newly discovered superconducting LaAlO₃/KTaO₃ interface, which can be attributed to spin-triplet pairing. These discoveries collectively have implications in various research fronts from superconducting spintronics to topological superconductivity.