Square Stacked Moiré Systems for Quantum Applications

Benjamin Feldman, Assistant Professor of Physics

Aharon Kapitulnik, Theodore and Sydney Rosenberg Professor of Applied Physics and Professor of Physics

Hemamala Karunadasa, J.G. Jackson and C.J. Wood Professor of Chemistry

Summary: Twisted-stacked van-der-Waals (vdW) heterostructures have yielded novel artificial materials, with an unprecedented wealth of emergent new physics associated with the underlying moiré lattice. Such stacked systems, including twisted bilayer graphene or transition metal dichalcogenide heterostructures, exhibit novel correlation effects, magnetism, unconventional superconductivity, or topologically ordered states of matter with fractionalized excitations, thus prompting intense theoretical work to explain the plethora of newly discovered ground states.

Consequently, it was recently recognized [1] that moiré heterostructures can also be used as unique condensed-matter quantum simulators, featuring a readily accessible tunability using external parameters such as gating, straining, packing and twist angle control. In their review, Kennes et al. [1] identify moiré heterostructures of vdW materials as an alternative and complementary condensed-matter approach to realize a large set of highly controllable quantum Hamiltonians. However, while the premise is to cover a wide range of lattices and their possible model Hamiltonians, this direction of materials engineering has so far focused solely on hexagonal vdW systems. While productive, it has limitations in symmetry, types of materials, interlayer coupling, and various fabrication issues.

Here we outline a program that will extend the twist and stack methodology to the vast library of perovskites, an idea that so far has been largely overlooked by the community because of its difficulty to execute. While most vdW materials are initially weakly interacting electronic systems, the usual starting point of perovskites is strong correlations. Homo- or mixed stacking of insulating perovskites can also be used to create conducting interfaces (e.g. [2]), where a twist-stacked moiré lattice may allow further control over the electronic structure [3]. This may lead e.g. to novel superconducting states and multiferroic behavior.