Quantum Monte Carlo Study of Semiconductor Artificial Graphene Nanostructures

Abstract

Semiconductor artificial graphene nanostructures where Hubbard model parameter $U/t$ can be of the order of 100, provide a highly controllable platform to study strongly correlated quantum many-particle phases. We use accurate variational and diffusion Monte Carlo methods to demonstrate a transition from antiferromagnetic to metallic phases for experimentally accessible lattice constant $a=50$ nm in terms of lattice site radius $\rho$, for finite sized artificial honeycomb structures nanopatterned on GaAs quantum wells containing up to 114 electrons. By analysing spin-spin correlation functions for hexagonal flakes with armchair edges and triangular flakes with zigzag edges, we show that edge type, geometry and charge nonuniformity affect the steepness and the crossover $\rho$ value of the phase transition. For triangular structures, the metal-insulator transition is accompanied with a smoother edge polarization transition.

5 pages, 5 figures; references added, several system sizes added, typos corrected; abstract updated

References in corpus (7)

• Topological Photonics
• Probing many-body dynamics on a 51-atom quantum simulator
• Magnetism in graphene nano-islands
• Continuous Mott transition in semiconductor moiré superlattices
• Two-dimensional Mott-Hubbard electrons in an artificial honeycomb lattice
• Engineering artificial graphene in a two-dimensional electron gas
• Quantum-gas microscopes - A new tool for cold-atom quantum simulators

Cited by in corpus (2)

• Superexchange Mechanism in Coupled Triangulenes Forming Spin-1 Chains
• Quantum Monte Carlo study of artificial triangular graphene quantum dots