High-Harmonic Generation with a twist: all-optical characterization of magic-angle twisted bilayer graphene

• URL: http://arxiv.org/abs/2302.04127v1
• Date: Sun, 5 Feb 2023 16:44:32 GMT
• Title: High-Harmonic Generation with a twist: all-optical characterization of magic-angle twisted bilayer graphene
• Authors: Eduardo B. Molinero, Anushree Datta, Mar\'ia J. Calder\'on, Elena Bascones, Rui E. F. Silva
• Abstract summary: We show that the band structure of magic-angle twisted bilayer graphene is imprinted onto its high-harmonic spectrum. Results show that high harmonic generation can be used as a spectroscopy tool for measuring the twist angle and also the electronic properties of twisted bilayer graphene.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: If we stack up two layers of graphene while changing their respective orientation by some twisting angle, we end up with a system that has striking differences when compared to single-layer graphene. For a very specific value of this twist angle, known as magic angle, twisted bilayer graphene displays a unique phase diagram that cannot be found in other systems. Recently, high harmonic generation spectroscopy has been successfully applied to elucidate the electronic properties of quantum materials. The purpose of the present work is to exploit the nonlinear optical response of magic-angle twisted bilayer graphene to unveil its electronic properties. We show that the band structure of magic-angle twisted bilayer graphene is imprinted onto its high-harmonic spectrum. Specifically, we observe a drastic decrease of harmonic signal as we approach the magic angle. Our results show that high harmonic generation can be used as a spectroscopy tool for measuring the twist angle and also the electronic properties of twisted bilayer graphene, paving the way for an all-optical characterization of moir\'e materials.

Related papers

• The multi-state geometry of shift current and polarization [44.99833362998488]
  We employ quantum state projectors to develop an explicitly gauge-invariant formalism. We provide a simple expression for the shift current that resolves its precise relation to the moments of electronic polarization. We reveal its decomposition into the sum of the skewness of the occupied states and intrinsic multi-state geometry.
  arXiv  Detail & Related papers  (2024-09-24T18:00:02Z)
• Graph Generation via Spectral Diffusion [51.60814773299899]
  We present GRASP, a novel graph generative model based on 1) the spectral decomposition of the graph Laplacian matrix and 2) a diffusion process. Specifically, we propose to use a denoising model to sample eigenvectors and eigenvalues from which we can reconstruct the graph Laplacian and adjacency matrix. Our permutation invariant model can also handle node features by concatenating them to the eigenvectors of each node.
  arXiv  Detail & Related papers  (2024-02-29T09:26:46Z)
• Through the Dual-Prism: A Spectral Perspective on Graph Data Augmentation for Graph Classification [71.36575018271405]
  We introduce the Dual-Prism (DP) augmentation method, comprising DP-Noise and DP-Mask. We find that keeping the low-frequency eigenvalues unchanged can preserve the critical properties at a large scale when generating augmented graphs.
  arXiv  Detail & Related papers  (2024-01-18T12:58:53Z)
• Modeling of electronic dynamics in twisted bilayer graphene [44.99833362998488]
  We consider the problem of numerically computing the quantum dynamics of an electron in twisted bilayer graphene. We first prove that the dynamics of the tight-binding model of incommensurate twisted bilayer graphene can be approximated by computations on finite domains. We then provide extensive numerical computations which clarify the range of validity of the Bistritzer-MacDonald model.
  arXiv  Detail & Related papers  (2023-08-21T02:50:13Z)
• Thermopower in hBN/graphene/hBN superlattices [46.287853697580566]
  We experimentally study thermopower in high-quality monolayer graphene within heterostructures consisting of complete hBN encapsulation and 1D edge contacts. We show that the temperature dependence of the thermopower enables the assessment of the role of built-in strain variation and van Hove singularities. We show the same superlattice device can exhibit a temperature-driven thermopower reversal from positive to negative and vice versa, by controlling the carrier density.
  arXiv  Detail & Related papers  (2023-06-14T19:06:34Z)
• Engineering flat bands in twisted-bilayer graphene away from the magic angle with chiral optical cavities [0.0]
  We show that by employing chiral optical cavities, the topological flat bands can be stabilized away from the magic angle. Time reversal symmetry breaking plays a fundamental role in flattening the isolated bands and gapping out the rest of the spectrum. Our results demonstrate the possibility of engineering flat bands in TBG using optical devices.
  arXiv  Detail & Related papers  (2023-06-08T12:17:44Z)
• Twisted bilayered graphenes at magic angles and Casimir interactions: correlation-driven effects [0.0]
  Twisted bilayered graphenes at magic angles are a fertile ground for novel states driven by electronic correlations. Here we find that the ubiquitous Casimir force can serve as a platform for macroscopic manifestations of the quantum effects stemming from the magic angle bilayered graphenes properties.
  arXiv  Detail & Related papers  (2022-10-05T16:44:49Z)
• Tunable bandgaps and flat bands in twisted bilayer biphenylene carbon [1.0934800950965333]
  twisted bilayer biphenylene carbon (BPC) is a promising material for the application of terahertz and infrared photodetectors. The flat bands in twisted BPC are no longer restricted by "magic angles", i.e., abnormal flat bands could be appeared as well as several specific large angles in addition to the small angles.
  arXiv  Detail & Related papers  (2021-08-17T02:29:17Z)
• Magic angle twisted bilayer graphene as a highly efficient quantum Otto engine [3.655021726150369]
  We design a highly efficient quantum Otto engine using a twisted bilayer graphene sample. It is observed that the efficiency varies smoothly with the twist angle and the maximum is attained at the magic angle.
  arXiv  Detail & Related papers  (2021-03-24T13:20:43Z)
• Spectra of Perfect State Transfer Hamiltonians on Fractal-Like Graphs [62.997667081978825]
  We study the spectral features, on fractal-like graphs, of Hamiltonians which exhibit the special property of perfect quantum state transfer. The essential goal is to develop the theoretical framework for understanding the interplay between perfect quantum state transfer, spectral properties, and the geometry of the underlying graph.
  arXiv  Detail & Related papers  (2020-03-25T02:46:14Z)
• Simulating twistronics without a twist [0.0]
  We propose a highly tunable scheme to synthetically emulate twisted bilayer systems with ultracold atoms trapped in an optical lattice. In our scheme, neither a physical bilayer nor twist is directly realized. Instead, two synthetic layers are produced exploiting coherently-coupled internal atomic states. To illustrate this concept, we focus on a synthetic square bilayer lattice and show that it leads to tunable quasi-flatbands and Dirac cone spectra under certain magic supercell periodicities.
  arXiv  Detail & Related papers  (2019-12-29T21:23:54Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.