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Novel two-dimensional (2D) atomically flat materials, such as graphene and transition-metal dichalcogenides, exhibit unconventional Dirac electronic spectra. We propose to effectively engineer their interactions with cold atoms in…

Lateral superlattices have attracted major interest as this may allow one to modify spectra of two dimensional electron systems and, ultimately, create materials with tailored electronic properties. Previously, it proved difficult to…

Two-dimensional Dirac semimetals have attracted much attention because of their linear energy dispersion and non-trivial Berry phase. Graphene-like 2D Dirac materials are gapless only within certain approximations, e.g., if spin-orbit…

Mesoscale and Nanoscale Physics · Physics 2022-02-16 Amarnath Chakraborty , Guang Bian , Giovanni Vignale

The Dirac cone underlies many unique electronic properties of graphene and topological insulators, and its band structure--two conical bands touching at a single point--has also been realized for photons in waveguide arrays, atoms in…

We demonstrate from a fundamental perspective the physical and mathematical origins of band warping and band non-parabolicity in electronic and vibrational structures. Remarkably, we find a robust presence and connection with pairs of…

Mesoscale and Nanoscale Physics · Physics 2017-09-13 Lorenzo Resca , Nicholas A. Mecholsky , Ian L. Pegg

Proximity orbital and spin-orbital effects of graphene on monolayer transition-metal dichalcogenides (TMDCs) are investigated from first-principles. The Dirac band structure of graphene is found to lie within the semiconducting gap of TMDCs…

Mesoscale and Nanoscale Physics · Physics 2016-04-27 Martin Gmitra , Denis Kochan , Petra Högl , Jaroslav Fabian

Based on their formation mechanisms, Dirac points in three-dimensional systems can be classified as accidental or essential. The former can be further distinguished into type-I and type-II, depending on whether the Dirac cone spectrum is…

Materials Science · Physics 2017-09-12 Cong Chen , Shan-Shan Wang , Lei Liu , Zhi-Ming Yu , Xian-Lei Sheng , Ziyu Chen , Shengyuan A. Yang

We investigate the influence of SiO2, Au, Ag, Cu, and Pt substrates on the Raman spectrum of graphene. Experiments reveal particularly strong modifications to the intensity, position, width, and shape of the Raman signal of graphene on…

Materials Science · Physics 2015-06-16 Qin Zhou , Sinisa Coh , Marvin L. Cohen , Steven G. Louie , A. Zettl

Quantum materials that host a flat band, such as pseudospin-1 lattices and magic-angle twisted bilayer graphene, can exhibit drastically new physical phenomena including unconventional superconductivity, orbital ferromagnetism, and Chern…

Mesoscale and Nanoscale Physics · Physics 2020-07-01 Hong-Ya Xu , Ying-Cheng Lai

Electrons in solids are characterized by the energy bands, which indicate that electrons are considered to be "elementary particles" with specific effective masses and g-factors reflecting features of each solid. There are cases where these…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 Hidetoshi Fukuyama , Akito Kobayashi , Yoshikazu Suzumura

We have calculated the dynamical optical conductivity for $\alpha-\mathcal{T}_3$ materials in the presence of a finite bandgap in their energy bandstructure. This is a special type of energy dispersions because for all…

Materials Science · Physics 2023-05-31 Andrii Iurov , Liubov Zhemchuzhna , Godfrey Gumbs , Danhong Huang

Square-octagon lattice underlies the description of a family of two-dimensional materials such as tetragraphene. In the present paper we show that the tight-binding model of square-octagon lattice contains both conventional and high-order…

Strongly Correlated Electrons · Physics 2021-05-13 D. O. Oriekhov , V. P. Gusynin , V. M. Loktev

We analyze the energy spectrum of graphene in the presence of spin-orbit coupling and a unidirectionally periodic Zeeman field, focusing on the stability and location of Dirac points it may support. It is found that the Dirac points at the…

Mesoscale and Nanoscale Physics · Physics 2016-08-24 Luis Brey , A. R. Carvalho , H. A. Fertig

The band structure of ABC-stacked N-layer graphene comprises topologically corresponding flat surface and gapped bulk subbands, as a consequence of the unique stacking configuration. In this paper, the bulk subbands are for the first times…

Mesoscale and Nanoscale Physics · Physics 2017-05-31 Ching-Hong Ho , Cheng-Peng Chang , Ming-Fa Lin

Orbitronics has recently emerged as a very active research topic after several proposals aiming to exploit the orbital degree of freedom for charge-free electronics. In this communication, we investigate orbital transport in selected…

Mesoscale and Nanoscale Physics · Physics 2023-12-13 Armando Pezo , Diego García Ovalle , Aurélien Manchon

The Coulomb interaction among massless Dirac fermions in graphene is unscreened around the isotropic Dirac points, causing a logarithmic velocity renormalization and a cone reshaping. In less symmetric Dirac materials possessing anisotropic…

We present a formalism to calculate the orbital magnetization of interacting Dirac fermions under a magnetic field. In this approach, the divergence difficulty is overcome with a special limit of the derivative of the thermodynamic…

Strongly Correlated Electrons · Physics 2017-09-05 Xin-Zhong Yan , C. S. Ting

We present a framework to elucidate the existence of accidental contacts of energy bands, particularly those called Dirac points which are the point contacts with linear energy dispersions in their vicinity. A generalized von-Neumann-Wigner…

Materials Science · Physics 2015-05-27 Kenichi Asano , Chisa Hotta

Since the discovery of magic-angle twisted bilayer graphene (TBG), flat bands in Dirac materials have become a prominent platform for realizing strong correlation effects in electronic systems. Here we show that the symmetry group…

Strongly Correlated Electrons · Physics 2023-12-20 Yarden Sheffer , Raquel Queiroz , Ady Stern

The nodal and effectively relativistic dispersion featuring in a range of novel materials including two- dimensional graphene and three-dimensional Dirac and Weyl semimetals has attracted enormous interest during the past decade. Here, by…

Strongly Correlated Electrons · Physics 2018-04-11 Johan Carlström , Emil J. Bergholtz