Concrete

/Tag: Concrete

Phase field crystal model for heterostructures. (arXiv:1908.05564v1 [cond-mat.mes-hall])

2019-08-16T04:30:42+00:00August 16th, 2019|Categories: Publications|Tags: , , , , |

Atomically thin 2-dimensional heterostructures are a promising, novel class of materials with groundbreaking properties. The possiblity of choosing the many constituent components and their proportions allows optimizing these materials to specific requirements. The wide adaptability comes with a cost of large parameter space making it hard to experimentally test all the possibilities. Instead, efficient computational modelling is needed. However, large range of relevant time and length scales related to physics of polycrystalline materials poses a challenge for computational studies. To this end, we present an efficient and flexible phase-field crystal model to describe the atomic configurations of multiple atomic species and phases coexisting in the same physical domain. We extensively benchmark the model for two-dimensional binary systems in terms of their elastic properties and phase boundary configurations and their energetics. As a concrete example, we demonstrate modelling lateral heterostructures of graphene and hexagonal boron nitride. We consider both idealized bicrystals and large-scale systems with random phase distributions. We find consistent relative elastic moduli and lattice constants, as well as realistic continuous interfaces and faceted crystal shapes. Zigzag-oriented interfaces are observed to display the lowest formation energy.

Published : "arXiv Mesoscale and Nanoscale Physics".

Two-dimensional second-order topological insulator in graphdiyne. (arXiv:1904.09985v1 [cond-mat.mes-hall])

2019-04-24T02:29:21+00:00April 24th, 2019|Categories: Publications|Tags: |

A second-order topological insulator (SOTI) in $d$ spatial dimensions features topologically protected gapless states at its $(d-2)$-dimensional boundary at the intersection of two crystal faces, but is gapped otherwise. As a novel topological state, it has been attracting great interest, but it remains a challenge to identify a realistic SOTI material in two dimensions (2D). Here, based on first-principles calculations and theoretical analysis, we reveal the already experimentally synthesized large gap semiconductor graphdiyne as the first realistic example of a 2D SOTI, with topologically protected 0D corner states. The role of crystalline symmetry, the robustness against symmetry-breaking, and the possible experimental characterization are discussed. Our results uncover a hidden topological character of graphdiyne and promote it as a concrete material platform for exploring the intriguing physics of higher-order topological phases.

Published in: "arXiv Material Science".

Entanglement signatures of emergent Dirac fermions: Kagome spin liquid and quantum criticality

2018-11-09T20:36:26+00:00November 9th, 2018|Categories: Publications|Tags: |

Quantum spin liquids (QSLs) are exotic phases of matter that host fractionalized excitations. It is difficult for local probes to characterize QSL, whereas quantum entanglement can serve as a powerful diagnostic tool due to its nonlocality. The kagome antiferromagnetic Heisenberg model is one of the most studied and experimentally relevant

Published in: "Science Advances".

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