The electronic properties of graphene
TL;DR: In this paper, the basic theoretical aspects of graphene, a one-atom-thick allotrope of carbon, with unusual two-dimensional Dirac-like electronic excitations, are discussed.
Abstract: This article reviews the basic theoretical aspects of graphene, a one-atom-thick allotrope of carbon, with unusual two-dimensional Dirac-like electronic excitations. The Dirac electrons can be controlled by application of external electric and magnetic fields, or by altering sample geometry and/or topology. The Dirac electrons behave in unusual ways in tunneling, confinement, and the integer quantum Hall effect. The electronic properties of graphene stacks are discussed and vary with stacking order and number of layers. Edge (surface) states in graphene depend on the edge termination (zigzag or armchair) and affect the physical properties of nanoribbons. Different types of disorder modify the Dirac equation leading to unusual spectroscopic and transport properties. The effects of electron-electron and electron-phonon interactions in single layer and multilayer graphene are also presented.
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TL;DR: This work reviews the historical development of Transition metal dichalcogenides, methods for preparing atomically thin layers, their electronic and optical properties, and prospects for future advances in electronics and optoelectronics.
Abstract: Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.
13,348 citations
TL;DR: This review analyzes recent trends in graphene research and applications, and attempts to identify future directions in which the field is likely to develop.
Abstract: Graphene is a wonder material with many superlatives to its name. It is the thinnest known material in the universe and the strongest ever measured. Its charge carriers exhibit giant intrinsic mobility, have zero effective mass, and can travel for micrometers without scattering at room temperature. Graphene can sustain current densities six orders of magnitude higher than that of copper, shows record thermal conductivity and stiffness, is impermeable to gases, and reconciles such conflicting qualities as brittleness and ductility. Electron transport in graphene is described by a Dirac-like equation, which allows the investigation of relativistic quantum phenomena in a benchtop experiment. This review analyzes recent trends in graphene research and applications, and attempts to identify future directions in which the field is likely to develop.
12,117 citations
TL;DR: Topological superconductors are new states of quantum matter which cannot be adiabatically connected to conventional insulators and semiconductors and are characterized by a full insulating gap in the bulk and gapless edge or surface states which are protected by time reversal symmetry.
Abstract: Topological insulators are new states of quantum matter which cannot be adiabatically connected to conventional insulators and semiconductors. They are characterized by a full insulating gap in the bulk and gapless edge or surface states which are protected by time-reversal symmetry. These topological materials have been theoretically predicted and experimentally observed in a variety of systems, including HgTe quantum wells, BiSb alloys, and Bi2Te3 and Bi2Se3 crystals. Theoretical models, materials properties, and experimental results on two-dimensional and three-dimensional topological insulators are reviewed, and both the topological band theory and the topological field theory are discussed. Topological superconductors have a full pairing gap in the bulk and gapless surface states consisting of Majorana fermions. The theory of topological superconductors is reviewed, in close analogy to the theory of topological insulators.
11,092 citations
TL;DR: An overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.
Abstract: There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.
8,919 citations
TL;DR: This Review describes how the tunable electronic structure of TMDs makes them attractive for a variety of applications, as well as electrically active materials in opto-electronics.
Abstract: Ultrathin two-dimensional nanosheets of layered transition metal dichalcogenides (TMDs) are fundamentally and technologically intriguing. In contrast to the graphene sheet, they are chemically versatile. Mono- or few-layered TMDs - obtained either through exfoliation of bulk materials or bottom-up syntheses - are direct-gap semiconductors whose bandgap energy, as well as carrier type (n- or p-type), varies between compounds depending on their composition, structure and dimensionality. In this Review, we describe how the tunable electronic structure of TMDs makes them attractive for a variety of applications. They have been investigated as chemically active electrocatalysts for hydrogen evolution and hydrosulfurization, as well as electrically active materials in opto-electronics. Their morphologies and properties are also useful for energy storage applications such as electrodes for Li-ion batteries and supercapacitors.
7,903 citations
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TL;DR: In this paper, the transverse magnetoconductance of two-dimensional electron gas in strong magnetic field is calculated on the basis of the model and approximation used in a previous paper, and the results are discussed in connection with the experiment of Fowler, Fang, Howard and Stiles.
Abstract: Transverse magnetoconductance of two-dimensional electron gas in strong magnetic field is calculated on the basis of the model and approximation used in a previous paper. Calculating two particle Green's function consistently with the approximation for one particle Green's function yields transverse magnetoconductance free from divergence. Strong energy dependence of one particle spectral density leads to some characteristic features of two-dimensional electron gas in strong magnetic fields. Transverse magnetoconductance calculated as a function of gate voltage exhibits broadening of Landau levels and is sharply cut off in midgap regions between Landau levels. These results are discussed in connection with the experiment of Fowler, Fang, Howard and Stiles. Within the model and approximation of the present paper, splittings of Landau levels are also obtained in strong magnetic field.
13 citations
TL;DR: An instability of a diffusive Fermi liquid, indicative of a metal-insulator transition (expected to be of first order), arising solely from the competition between quenched disorder and short-ranged interparticle interactions is identified in Hubbard-like models for spinless fermions, subject to (complex) random hopping at half-filling on bipartite lattices as discussed by the authors.
Abstract: An instability of a diffusive Fermi liquid, indicative of a metal-insulator transition (expected to be of first order), arising solely from the competition between quenched disorder and short-ranged interparticle interactions is identified in Hubbard-like models for spinless fermions, subject to (complex) random hopping at half-filling on bipartite lattices. The instability, found within a Finkel'stein Non-Linear Sigma Model treatment in d = (2 + epsilon) > 2 dimensions, originates from an underlying particle-hole like (so-called "chiral") symmetry, shared by both disorder and interactions. In the clean, interacting Fermi liquid this symmetry is responsible for the (completely different) "nesting" instability.
13 citations
"The electronic properties of graphe..." refers background in this paper
...…of intera ting ele -trons in a random gauge eld suggests the possibilityof non-trivial phases (Aleiner and Efetov, 2006; Altland, 2006; Dell'Anna, 2006; Foster and Ludwig, 2006a,b;Khvesh henko, 2007; Nomura et al., 2007; Stauber et al.,2005), where intera tions and disorder an el ea h other....
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TL;DR: In this article, the effect of the SiO2 substrate on a graphene film is investigated using realistic but computationally convenient energy-optimized models of the substrate supporting a layer of graphene.
Abstract: The effect of the SiO2 substrate on a graphene film is investigated using realistic but computationally convenient energy-optimized models of the substrate supporting a layer of graphene. The electronic bands are calculated using density functional methods for several model substrates. This provides an estimate of the substrate charge effects on the behaviour of the bands near EF, as well as the local variation of the Fermi energy of the graphene sheet. A model of a wavy graphene layer positioned on the substrate is used to help understand the nature of the minimum conductance of graphene.
12 citations
"The electronic properties of graphe..." refers background in this paper
...Ab initio band stru ture al ulations also givesupport to this s enario (Dharma-Wardana, 2007)....
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TL;DR: Numerical study of the Dirac fermions in partially filled N=3 Landau level (LL) in graphene shows a symmetry broken stripe phase is formed at large system size limit, which is robust against perturbation from disorder scattering.
Abstract: We report on numerical study of the Dirac fermions in partially filled N = 3 Landau level (LL) in graphene. At half-filling, the equal-time density-density correlation function displays sharp peaks at nonzero wave vectors ±q*. Finite-size scaling shows that the peak value grows with electron number and diverges in the thermodynamic limit, which suggests an instability toward a charge density wave. A symmetry broken stripe phase is formed at large system size limit, which is robust against perturbation from disorder scattering. Such a quantum phase is experimentally observable through transport measurements. Associated with the special wave functions of the Dirac LL, both stripe and bubble phases become possible candidates for the ground state of the Dirac fermions in graphene with lower filling factors in the N = 3 LL.
11 citations
TL;DR: In this article, a formalism is proposed to study the electron tunneling between extended states, based on the spin-boson Hamiltonian previously used in two-level systems, which is applied to analyze the out-of-plane tunneling in layered metals considering different models.
Abstract: A formalism is proposed to study the electron tunneling between extended states, based on the spin-boson Hamiltonian previously used in two-level systems. It is applied to analyze the out-of-plane tunneling in layered metals considering different models. By studying the effects of in-plane interactions on the interlayer tunneling of electrons near the Fermi level, we establish the relation between departure from Fermi-liquid behavior driven by electron correlations inside the layer and the out of plane coherence. Response functions, directly comparable with experimental data are obtained.
10 citations
"The electronic properties of graphe..." refers background in this paper
...The vanishing of thequasiparti le peak at low energies an lead to an en-ergy dependent renormalization of the interlayer hopping(Vozmediano et al., 2002, 2003)....
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