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Lihm JM, Park CH. Plasmon-Phonon Hybridization in Doped Semiconductors from First Principles. PHYSICAL REVIEW LETTERS 2024; 133:116402. [PMID: 39332011 DOI: 10.1103/physrevlett.133.116402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 07/24/2024] [Indexed: 09/29/2024]
Abstract
Although plasmons and phonons are the collective excitations that govern the low-energy physics of doped semiconductors, their nonadiabatic hybridization and mutual screening have not been studied from first principles. We achieve this goal by transforming the Dyson equation to the frequency-independent dynamical matrix of an equivalent damped oscillator. Calculations on doped GaAs and TiO_{2} agree well with available Raman data and await immediate experimental confirmation from infrared, neutron, electron-energy-loss, and angle-resolved photoemission spectroscopies.
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2
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Sidiropoulos TPH, Di Palo N, Rivas DE, Summers A, Severino S, Reduzzi M, Biegert J. Enhanced optical conductivity and many-body effects in strongly-driven photo-excited semi-metallic graphite. Nat Commun 2023; 14:7407. [PMID: 37973799 PMCID: PMC10654445 DOI: 10.1038/s41467-023-43191-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 11/02/2023] [Indexed: 11/19/2023] Open
Abstract
The excitation of quasi-particles near the extrema of the electronic band structure is a gateway to electronic phase transitions in condensed matter. In a many-body system, quasi-particle dynamics are strongly influenced by the electronic single-particle structure and have been extensively studied in the weak optical excitation regime. Yet, under strong optical excitation, where light fields coherently drive carriers, the dynamics of many-body interactions that can lead to new quantum phases remain largely unresolved. Here, we induce such a highly non-equilibrium many-body state through strong optical excitation of charge carriers near the van Hove singularity in graphite. We investigate the system's evolution into a strongly-driven photo-excited state with attosecond soft X-ray core-level spectroscopy. We find an enhancement of the optical conductivity of nearly ten times the quantum conductivity and pinpoint it to carrier excitations in flat bands. This interaction regime is robust against carrier-carrier interaction with coherent optical phonons acting as an attractive force reminiscent of superconductivity. The strongly-driven non-equilibrium state is markedly different from the single-particle structure and macroscopic conductivity and is a consequence of the non-adiabatic many-body state.
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Affiliation(s)
- T P H Sidiropoulos
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Barcelona, Spain.
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489, Berlin, Germany.
| | - N Di Palo
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Barcelona, Spain
| | - D E Rivas
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Barcelona, Spain
| | - A Summers
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Barcelona, Spain
| | - S Severino
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Barcelona, Spain
| | - M Reduzzi
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Barcelona, Spain
| | - J Biegert
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Barcelona, Spain.
- ICREA - Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain.
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3
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Düvel M, Merboldt M, Bange JP, Strauch H, Stellbrink M, Pierz K, Schumacher HW, Momeni D, Steil D, Jansen GSM, Steil S, Novko D, Mathias S, Reutzel M. Far-from-Equilibrium Electron-Phonon Interactions in Optically Excited Graphene. NANO LETTERS 2022; 22:4897-4904. [PMID: 35649249 DOI: 10.1021/acs.nanolett.2c01325] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Comprehending far-from-equilibrium many-body interactions is one of the major goals of current ultrafast condensed matter physics research. Here, a particularly interesting but barely understood situation occurs during a strong optical excitation, where the electron and phonon systems can be significantly perturbed and the quasiparticle distributions cannot be described with equilibrium functions. In this work, we use time- and angle-resolved photoelectron spectroscopy to study such far-from-equilibrium many-body interactions for the prototypical material graphene. In accordance with theoretical simulations, we find remarkable transient renormalizations of the quasiparticle self-energy caused by the photoinduced nonequilibrium conditions. These observations can be understood by ultrafast scatterings between nonequilibrium electrons and strongly coupled optical phonons, which signify the crucial role of ultrafast nonequilibrium dynamics on many-body interactions. Our results advance the understanding of many-body physics in extreme conditions, which is important for any endeavor to optically manipulate or create non-equilibrium states of matter.
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Affiliation(s)
- Marten Düvel
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Marco Merboldt
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Jan Philipp Bange
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Hannah Strauch
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Michael Stellbrink
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Klaus Pierz
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
| | | | - Davood Momeni
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
| | - Daniel Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - G S Matthijs Jansen
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Sabine Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Dino Novko
- Institute of Physics, HR-10000 Zagreb, Croatia
| | - Stefan Mathias
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- International Center for Advanced Studies of Energy Conversion (ICASEC), University of Göttingen, 37077 Göttingen, Germany
| | - Marcel Reutzel
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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4
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Prasad N, Burg GW, Watanabe K, Taniguchi T, Register LF, Tutuc E. Quantum Lifetime Spectroscopy and Magnetotunneling in Double Bilayer Graphene Heterostructures. PHYSICAL REVIEW LETTERS 2021; 127:117701. [PMID: 34558942 DOI: 10.1103/physrevlett.127.117701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/31/2021] [Indexed: 06/13/2023]
Abstract
We describe a tunneling spectroscopy technique in a double bilayer graphene heterostructure where momentum-conserving tunneling between different energy bands serves as an energy filter for the tunneling carriers, and allows a measurement of the quasiparticle state broadening at well-defined energies. The broadening increases linearly with the excited state energy with respect to the Fermi level and is weakly dependent on temperature. In-plane magnetotunneling reveals a high degree of rotational alignment between the graphene bilayers, and an absence of momentum randomizing processes.
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Affiliation(s)
- Nitin Prasad
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, USA
| | - G William Burg
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, USA
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan
| | - Leonard F Register
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, USA
| | - Emanuel Tutuc
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, USA
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5
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Chiu CW, Chung YL, Yang CH, Liu CT, Lin CY. Coulomb decay rates in monolayer doped graphene. RSC Adv 2020; 10:2337-2346. [PMID: 35494571 PMCID: PMC9048988 DOI: 10.1039/c9ra05953a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 12/16/2019] [Indexed: 11/21/2022] Open
Abstract
Excited conduction electrons, conduction holes, and valence holes in monolayer electron-doped graphene exhibit unusual Coulomb decay rates. The deexcitation processes are studied using the screened exchange energy. They might utilize the intraband and interband single-particle excitations, as well as the plasmon modes, depending on the quasiparticle states and the Fermi energies. The low-lying valence holes can decay through the undamped acoustic plasmon, so that they present very fast Coulomb deexcitations, nonmonotonous energy dependence, and anisotropic behavior. However, the low-energy conduction electrons and holes are similar to those in a two-dimensional electron gas. The higher-energy conduction states and the deeper-energy valence ones behave similarly in the available deexcitation channels and have a similar dependence of decay rate on the wave vector.
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Affiliation(s)
- Chih-Wei Chiu
- Department of Physics, National Kaohsiung Normal University Kaohsiung 824 Taiwan
| | - Yue-Lin Chung
- Department of Physics, National Kaohsiung Normal University Kaohsiung 824 Taiwan
| | - Cheng-Hsueh Yang
- Department of Physics, National Cheng Kung University Tainan 701 Taiwan
| | - Chang-Ting Liu
- Department of Physics, National Kaohsiung Normal University Kaohsiung 824 Taiwan
| | - Chiun-Yan Lin
- Department of Physics, National Cheng Kung University Tainan 701 Taiwan
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6
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Sjakste J, Tanimura K, Barbarino G, Perfetti L, Vast N. Hot electron relaxation dynamics in semiconductors: assessing the strength of the electron-phonon coupling from the theoretical and experimental viewpoints. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:353001. [PMID: 30084390 DOI: 10.1088/1361-648x/aad487] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The rapid development of the computational methods based on density functional theory, on the one hand, and of time-, energy-, and momentum-resolved spectroscopy, on the other hand, allows today an unprecedently detailed insight into the processes governing hot-electron relaxation dynamics, and, in particular, into the role of the electron-phonon coupling. Instead of focusing on the development of a particular method, theoretical or experimental, this review aims to treat the progress in the understanding of the electron-phonon coupling which can be gained from both, on the basis of recently obtained results. We start by defining several regimes of hot electron relaxation via electron-phonon coupling, with respect to the electron excitation energy. We distinguish between energy and momentum relaxation of hot electrons, and summarize, for several semiconductors of the IV and III-V groups, the orders of magnitude of different relaxation times in different regimes, on the basis of known experimental and numerical data. Momentum relaxation times of hot electrons become very short around 1 eV above the bottom of the conduction band, and such ultrafast relaxation mechanisms are measurable only in the most recent pump-probe experiments. Then, we give an overview of the recent progress in the experimental techniques allowing to obtain detailed information on the hot-electron relaxation dynamics, with the main focus on time-, energy-, and momentum-resolved photoemission experiments. The particularities of the experimental approach developed by one of us, which allows to capture time-, energy-, and momentum-resolved hot-electron distributions, as well as to measure momentum relaxation times of the order of 10 fs, are discussed. We further discuss the main advances in the calculation of the electron-phonon scattering times from first principles over the past ten years, in semiconducting materials. Ab initio techniques and efficient interpolation methods provide the possibility to calculate electron-phonon scattering times with high precision at reasonable numerical cost. We highlight the methods of analysis of the obtained numerical results, which allow to give insight into the details of the electron-phonon scattering mechanisms. Finally, we discuss the concept of hot electron ensemble which has been proposed recently to describe the hot-electron relaxation dynamics in GaAs, the applicability of this concept to other materials, and its limitations. We also mention some open problems.
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Affiliation(s)
- J Sjakste
- Laboratoire des Solides Irradiés, Ecole Polytechnique, CEA-DRF-IRAMIS, CNRS UMR 7642, 91120 Palaiseau, France
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7
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Dirac Cones in Graphene, Interlayer Interaction in Layered Materials, and the Band Gap in MoS2. CRYSTALS 2016. [DOI: 10.3390/cryst6110143] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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8
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Rösner M, Steinke C, Lorke M, Gies C, Jahnke F, Wehling TO. Two-Dimensional Heterojunctions from Nonlocal Manipulations of the Interactions. NANO LETTERS 2016; 16:2322-2327. [PMID: 26918626 DOI: 10.1021/acs.nanolett.5b05009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We propose to create lateral heterojunctions in two-dimensional materials based on nonlocal manipulations of the Coulomb interaction using structured dielectric environments. By means of ab initio calculations for MoS2 as well as generic semiconductor models, we show that the Coulomb interaction-induced self-energy corrections in real space are sufficiently nonlocal to be manipulated externally, but still local enough to induce spatially sharp interfaces within a single homogeneous monolayer to form heterojunctions. We find a type-II heterojunction band scheme promoted by a laterally structured dielectric environment, which exhibits a sharp band gap crossover within less than 5 unit cells.
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Affiliation(s)
- M Rösner
- Institut für Theoretische Physik, Universität Bremen , Otto-Hahn-Allee 1, 28359 Bremen, Germany
- Bremen Center for Computational Materials Science, Universität Bremen , Am Fallturm 1a, 28359 Bremen, Germany
| | - C Steinke
- Institut für Theoretische Physik, Universität Bremen , Otto-Hahn-Allee 1, 28359 Bremen, Germany
- Bremen Center for Computational Materials Science, Universität Bremen , Am Fallturm 1a, 28359 Bremen, Germany
| | - M Lorke
- Institut für Theoretische Physik, Universität Bremen , Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - C Gies
- Institut für Theoretische Physik, Universität Bremen , Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - F Jahnke
- Institut für Theoretische Physik, Universität Bremen , Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - T O Wehling
- Institut für Theoretische Physik, Universität Bremen , Otto-Hahn-Allee 1, 28359 Bremen, Germany
- Bremen Center for Computational Materials Science, Universität Bremen , Am Fallturm 1a, 28359 Bremen, Germany
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9
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Verdi C, Giustino F. Fröhlich Electron-Phonon Vertex from First Principles. PHYSICAL REVIEW LETTERS 2015; 115:176401. [PMID: 26551127 DOI: 10.1103/physrevlett.115.176401] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Indexed: 06/05/2023]
Abstract
We develop a method for calculating the electron-phonon vertex in polar semiconductors and insulators from first principles. The present formalism generalizes the Fröhlich vertex to the case of anisotropic materials and multiple phonon branches, and can be used either as a postprocessing correction to standard electron-phonon calculations, or in conjunction with ab initio interpolation based on maximally localized Wannier functions. We demonstrate this formalism by investigating the electron-phonon interactions in anatase TiO(2), and show that the polar vertex significantly reduces the electron lifetimes and enhances the anisotropy of the coupling. The present work enables ab initio calculations of carrier mobilities, lifetimes, mass enhancement, and pairing in polar materials.
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Affiliation(s)
- Carla Verdi
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Feliciano Giustino
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
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10
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Hwang C. Angle-resolved photoemission spectroscopy study on graphene using circularly polarized light. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:335501. [PMID: 25056276 DOI: 10.1088/0953-8984/26/33/335501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We have investigated graphene using circularly polarized light via angle-resolved photoemission spectroscopy. We observe that photoelectron intensity rotates around a constant energy contour towards the opposite direction upon changing the chirality of light. Interestingly, the circular dichroism is found to be asymmetric with respect to the Dirac energy, which is not explained by the Berry phase effect (Liu et al 2011 Phys. Rev. Lett. 107 166803). We also report that the energy spectra taken using the light with different chiralities show a finite separation from each other. We discuss possible origins of the unusual circular dichroism observed in graphene.
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Affiliation(s)
- Choongyu Hwang
- Department of Physics, Pusan National University, Busan 609-735, Korea
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11
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Hwang J, LeBlanc JPF, Carbotte JP. Optical self-energy in graphene due to correlations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:245601. [PMID: 22609689 DOI: 10.1088/0953-8984/24/24/245601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In highly correlated systems one can define an optical self-energy in analogy to its quasiparticle (QP) self-energy counterpart. This quantity provides useful information on the nature of the excitations involved in inelastic scattering processes. Here we calculate the self-energy of the intraband optical transitions in graphene originating in the electron-electron interaction (EEI) as well as electron-phonon interaction (EPI). Although optics involves an average over all momenta (k) of the charge carriers, the structure in the optical self-energy is nevertheless found to mirror mainly that of the corresponding quasiparticles for k equal to or near the Fermi momentum k(F). Consequently, plasmaronic structures which are associated with momenta near the Dirac point at k = 0 are not important in the intraband optical response. While the structure of the electron-phonon interaction (EPI) reflects the sharp peaks of the phonon density of states, the excitation spectrum associated with the electron-electron interaction is in comparison structureless and flat and extends over an energy range which scales linearly with the value of the chemical potential. We introduce a method whereby detailed quantitative information on such excitation spectra can be extracted from optical data. Modulations seen on the edge of the interband optical conductivity as it rises towards its universal background value are traced to structure in the quasiparticle self-energies around k(F) of the lower Dirac cone associated with the occupied states.
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Affiliation(s)
- J Hwang
- Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi-do, Republic of Korea
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12
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Thongrattanasiri S, Manjavacas A, García de Abajo FJ. Quantum finite-size effects in graphene plasmons. ACS NANO 2012; 6:1766-75. [PMID: 22217250 DOI: 10.1021/nn204780e] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Graphene plasmons are emerging as an alternative solution to noble metal plasmons, adding the advantages of tunability via electrostatic doping and long lifetimes. These excitations have been so far described using classical electrodynamics, with the carbon layer represented by a local conductivity. However, the question remains, how accurately is such a classical description representing graphene? What is the minimum size for which nonlocal and quantum finite-size effects can be ignored in the plasmons of small graphene structures? Here, we provide a clear answer to these questions by performing first-principles calculations of the optical response of doped nanostructured graphene obtained from a tight-binding model for the electronic structure and the random-phase approximation for the dielectric response. The resulting plasmon energies are in good agreement with classical local electromagnetic theory down to ∼10 nm sizes, below which plasmons split into several resonances that emphasize the molecular character of the carbon structures and the quantum nature of their optical excitations. Additionally, finite-size effects produce substantial plasmon broadening compared to homogeneous graphene up to sizes well above 20 nm in nanodisks and 10 nm in nanoribbons. The atomic structure of edge terminations is shown to be critical, with zigzag edges contributing to plasmon broadening significantly more than armchair edges. This study demonstrates the ability of graphene nanostructures to host well-defined plasmons down to sizes below 10 nm, and it delineates a roadmap for understanding their main characteristics, including the role of finite size and nonlocality, thus providing a solid background for the emerging field of graphene nanoplasmonics.
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14
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Zhou Y, Jiang X, Duan G, Gao F, Zu X. Spin and band-gap engineering in copper-doped BN sheet. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.03.085] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Zhang Y, Tsu R. Binding graphene sheets together using silicon: graphene/silicon superlattice. NANOSCALE RESEARCH LETTERS 2010; 5:805-808. [PMID: 20672119 PMCID: PMC2893836 DOI: 10.1007/s11671-010-9561-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 02/03/2010] [Indexed: 05/29/2023]
Abstract
We propose a superlattice consisting of graphene and monolayer thick Si sheets and investigate it using a first-principles density functional theory. The Si layer is found to not only strengthen the interlayer binding between the graphene sheets compared to that in graphite, but also inject electrons into graphene, yet without altering the most unique property of graphene: the Dirac fermion-like electronic structure. The superlattice approach represents a new direction for exploring basic science and applications of graphene-based materials.
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Affiliation(s)
- Yong Zhang
- Department of Electrical and Computer Engineering and Center for Optoelectronics, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA.
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16
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Brar VW, Wickenburg S, Panlasigui M, Park CH, Wehling TO, Zhang Y, Decker R, Girit C, Balatsky AV, Louie SG, Zettl A, Crommie MF. Observation of carrier-density-dependent many-body effects in graphene via tunneling spectroscopy. PHYSICAL REVIEW LETTERS 2010; 104:036805. [PMID: 20366671 DOI: 10.1103/physrevlett.104.036805] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Indexed: 05/29/2023]
Abstract
We find the scanning tunneling spectra of backgated graphene monolayers to be significantly altered by many-body excitations. Experimental features in the spectra arising from electron-plasmon interactions show carrier density dependence, distinguishing them from density-independent electron-phonon features. Using a straightforward model, we are able to calculate theoretical tunneling spectra that agree well with our data, providing insight into the effects of many-body interactions on the lifetime of graphene quasiparticles.
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Affiliation(s)
- Victor W Brar
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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17
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Park CH, Giustino F, Spataru CD, Cohen ML, Louie SG. Angle-resolved photoemission spectra of graphene from first-principles calculations. NANO LETTERS 2009; 9:4234-4239. [PMID: 19856901 DOI: 10.1021/nl902448v] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Angle-resolved photoemission spectroscopy (ARPES) is a powerful experimental technique for directly probing electron dynamics in solids. The energy versus momentum dispersion relations and the associated spectral broadenings measured by ARPES provide a wealth of information on quantum many-body interaction effects. In particular, ARPES allows studies of the Coulomb interaction among electrons (electron-electron interactions) and the interaction between electrons and lattice vibrations (electron-phonon interactions). Here, we report ab initio simulations of the ARPES spectra of graphene including both electron-electron and electron-phonon interactions on the same footing. Our calculations reproduce some of the key experimental observations related to many-body effects, including the indication of a mismatch between the upper and lower halves of the Dirac cone.
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Affiliation(s)
- Cheol-Hwan Park
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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