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arXiv · 2210.14696

Quantum Monte Carlo Study of Semiconductor Artificial Graphene Nanostructures

Gökhan Öztarhan·E. Bulut Kul·Emre Okcu·A. D. Güçlü
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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.

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Gökhan Öztarhan, E. Bulut Kul, Emre Okcu, A. D. Güçlü. 2022-10-26. Quantum Monte Carlo Study of Semiconductor Artificial Graphene Nanostructures. https://doi.org/10.1103/physrevb.108.l161114

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