Van der Waals Reprogrammable Quantum Materials using Ultra-low Voltage E-beam Lithography

Understanding quantum materials and developing quantum hardware are consistent goals and challenges for quantum information science. Among the materials, van der Waals (vdW) materials and reconfigurable complex oxides show great potential to support the route by providing plentiful properties. Here we demonstrate how reconfigurable quantum materials can be achieved by gating vdW stacks with complex-oxide heterostructures that are programmed by ultra-low voltage e-beam lithography (ULV-EBL) [1]. This technique for nanoscale gating of vdW materials has the potential for instantiating a wide range of 2D Fermi-Hubbard models, and for creating emergent properties such as novel magnetic and superconducting phases. Here we explore the Kagome lattice which is imprinted into LaAlO₃/SrTiO₃ (LAO/STO). The full device integrates the reprogrammable conductive LAO/STO layer with a vdW stack consisting of hexagonal boron nitride (hBN) encapsulated bilayer graphene (BLG), with a multi-layer graphene top electrode. Transport measurements reveal a non-trivial Landau fan diagram which is absent from the control device. The overall approach can be expanded to include other complex oxides, vdW materials other than graphene, transition metal dichalcogenides (TMD), and complex oxide membranes, such as LAO/KTO, WSe₂, and LAO/STO membranes. The results obtained so far offer the promise of a reconfigurable method for creating novel electronic materials via analog quantum simulation.

[1] D. Yang et al, Appl. Phys. Lett. 117, 253103 (2020)