1
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Whelan PR, De Fazio D, Pasternak I, Thomsen JD, Zelzer S, Mikkelsen MO, Booth TJ, Diekhöner L, Sassi U, Johnstone D, Midgley PA, Strupinski W, Jepsen PU, Ferrari AC, Bøggild P. Mapping nanoscale carrier confinement in polycrystalline graphene by terahertz spectroscopy. Sci Rep 2024; 14:3163. [PMID: 38326379 PMCID: PMC10850153 DOI: 10.1038/s41598-024-51548-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 01/06/2024] [Indexed: 02/09/2024] Open
Abstract
Terahertz time-domain spectroscopy (THz-TDS) can be used to map spatial variations in electrical properties such as sheet conductivity, carrier density, and carrier mobility in graphene. Here, we consider wafer-scale graphene grown on germanium by chemical vapor deposition with non-uniformities and small domains due to reconstructions of the substrate during growth. The THz conductivity spectrum matches the predictions of the phenomenological Drude-Smith model for conductors with non-isotropic scattering caused by backscattering from boundaries and line defects. We compare the charge carrier mean free path determined by THz-TDS with the average defect distance assessed by Raman spectroscopy, and the grain boundary dimensions as determined by transmission electron microscopy. The results indicate that even small angle orientation variations below 5° within graphene grains influence the scattering behavior, consistent with significant backscattering contributions from grain boundaries.
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Affiliation(s)
- Patrick R Whelan
- DTU Physics, Technical University of Denmark, Fysikvej, Bld. 309, 2800, Kongens Lyngby, Denmark
- Department of Materials and Production, Aalborg University, Skjernvej 4A, 9220, Aalborg, Denmark
| | - Domenico De Fazio
- Cambridge Graphene Centre, University of Cambridge, 9 JJ Thomson Avenue, Cambridge, CB3 0FA, UK
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, 30172, Venice, Italy
| | - Iwona Pasternak
- Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662, Warsaw, Poland
- Vigo System S.A., 129/133 Poznanska Str, 05-850, Ozarow Mazowiecki, Poland
| | - Joachim D Thomsen
- DTU Physics, Technical University of Denmark, Fysikvej, Bld. 309, 2800, Kongens Lyngby, Denmark
| | - Steffen Zelzer
- Department of Materials and Production, Aalborg University, Skjernvej 4A, 9220, Aalborg, Denmark
| | - Martin O Mikkelsen
- Department of Materials and Production, Aalborg University, Skjernvej 4A, 9220, Aalborg, Denmark
| | - Timothy J Booth
- DTU Physics, Technical University of Denmark, Fysikvej, Bld. 309, 2800, Kongens Lyngby, Denmark
- Center for Nanostructured Graphene (CNG), Technical University of Denmark, Ørsteds Plads 345C, 2800, Kongens Lyngby, Denmark
| | - Lars Diekhöner
- Department of Materials and Production, Aalborg University, Skjernvej 4A, 9220, Aalborg, Denmark
| | - Ugo Sassi
- Cambridge Graphene Centre, University of Cambridge, 9 JJ Thomson Avenue, Cambridge, CB3 0FA, UK
| | - Duncan Johnstone
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK
| | - Paul A Midgley
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK
| | - Wlodek Strupinski
- Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662, Warsaw, Poland
- Vigo System S.A., 129/133 Poznanska Str, 05-850, Ozarow Mazowiecki, Poland
| | - Peter U Jepsen
- Center for Nanostructured Graphene (CNG), Technical University of Denmark, Ørsteds Plads 345C, 2800, Kongens Lyngby, Denmark
- DTU Fotonik, Technical University of Denmark, Ørsteds Plads 343, 2800, Kongens Lyngby, Denmark
| | - Andrea C Ferrari
- Cambridge Graphene Centre, University of Cambridge, 9 JJ Thomson Avenue, Cambridge, CB3 0FA, UK
| | - Peter Bøggild
- DTU Physics, Technical University of Denmark, Fysikvej, Bld. 309, 2800, Kongens Lyngby, Denmark.
- Center for Nanostructured Graphene (CNG), Technical University of Denmark, Ørsteds Plads 345C, 2800, Kongens Lyngby, Denmark.
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2
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Zummo F, Esposito P, Hou H, Wetzl C, Rius G, Tkatchenko R, Guimera A, Godignon P, Prato M, Prats-Alfonso E, Criado A, Scaini D. Bidirectional Modulation of Neuronal Cells Electrical and Mechanical Properties Through Pristine and Functionalized Graphene Substrates. Front Neurosci 2022; 15:811348. [PMID: 35087375 PMCID: PMC8788235 DOI: 10.3389/fnins.2021.811348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 12/01/2021] [Indexed: 11/13/2022] Open
Abstract
In recent years, the quest for surface modifications to promote neuronal cell interfacing and modulation has risen. This course is justified by the requirements of emerging technological and medical approaches attempting to effectively interact with central nervous system cells, as in the case of brain-machine interfaces or neuroprosthetic. In that regard, the remarkable cytocompatibility and ease of chemical functionalization characterizing surface-immobilized graphene-based nanomaterials (GBNs) make them increasingly appealing for these purposes. Here, we compared the (morpho)mechanical and functional adaptation of rat primary hippocampal neurons when interfaced with surfaces covered with pristine single-layer graphene (pSLG) and phenylacetic acid-functionalized single-layer graphene (fSLG). Our results confirmed the intrinsic ability of glass-supported single-layer graphene to boost neuronal activity highlighting, conversely, the downturn inducible by the surface insertion of phenylacetic acid moieties. fSLG-interfaced neurons showed a significant reduction in spontaneous postsynaptic currents (PSCs), coupled to reduced cell stiffness and altered focal adhesion organization compared to control samples. Overall, we have here demonstrated that graphene substrates, both pristine and functionalized, could be alternatively used to intrinsically promote or depress neuronal activity in primary hippocampal cultures.
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Affiliation(s)
- Francesca Zummo
- Neuroscience Area, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Pietro Esposito
- Neuroscience Area, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Huilei Hou
- Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), San Sebastián, Spain
| | - Cecilia Wetzl
- Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), San Sebastián, Spain
| | - Gemma Rius
- Institut de Microelectrònica de Barcelona, IMB-CNM (CSIC), Esfera UAB, Bellaterra, Spain
| | - Raphaela Tkatchenko
- Institut de Microelectrònica de Barcelona, IMB-CNM (CSIC), Esfera UAB, Bellaterra, Spain
| | - Anton Guimera
- Institut de Microelectrònica de Barcelona, IMB-CNM (CSIC), Esfera UAB, Bellaterra, Spain
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Madrid, Spain
| | - Philippe Godignon
- Institut de Microelectrònica de Barcelona, IMB-CNM (CSIC), Esfera UAB, Bellaterra, Spain
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Madrid, Spain
| | - Maurizio Prato
- Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), San Sebastián, Spain
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, Italy
- Basque Foundation for Science (IKERBASQUE), Bilbao, Spain
| | - Elisabet Prats-Alfonso
- Institut de Microelectrònica de Barcelona, IMB-CNM (CSIC), Esfera UAB, Bellaterra, Spain
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Madrid, Spain
- *Correspondence: Elisabet Prats-Alfonso,
| | - Alejandro Criado
- Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), San Sebastián, Spain
- Centro de Investigacións Científicas Avanzadas (CICA), Universidade da Coruña, A Coruña, Spain
- Alejandro Criado,
| | - Denis Scaini
- Neuroscience Area, International School for Advanced Studies (SISSA), Trieste, Italy
- Nanomedicine Research Laboratory, Department of Medicine, Imperial College London, Hammersmith Hospital, London, United Kingdom
- Denis Scaini,
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3
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Sonntag J, Reichardt S, Beschoten B, Stampfer C. Electrical Control over Phonon Polarization in Strained Graphene. NANO LETTERS 2021; 21:2898-2904. [PMID: 33797265 DOI: 10.1021/acs.nanolett.0c05043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We explore the tunability of the phonon polarization in suspended uniaxially strained graphene by magneto-phonon resonances. The uniaxial strain lifts the degeneracy of the LO and TO phonons, yielding two cross-linearly polarized phonon modes and a splitting of the Raman G peak. We utilize the strong electron-phonon coupling in graphene and the off-resonant coupling to a magneto-phonon resonance to induce a gate-tunable circular phonon dichroism. This, together with the strain-induced splitting of the G peak, allows us to controllably tune the two linearly polarized G mode phonons into circular phonon modes. We are able to achieve a circular phonon polarization of up to 40% purely by electrostatic fields and can reverse its sign by tuning from electron to hole doping. This provides unprecedented electrostatic control over the angular momentum of phonons, which paves the way toward phononic applications.
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Affiliation(s)
- Jens Sonntag
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Sven Reichardt
- Department of Physics and Materials Science, University of Luxembourg, L-1511 Luxembourg, Luxembourg
| | - Bernd Beschoten
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany
| | - Christoph Stampfer
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
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4
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Ben Gouider Trabelsi A, V. Kusmartsev F, Kusmartseva A, H. Alkallas F, AlFaify S, Shkir M. Raman Spectroscopy Imaging of Exceptional Electronic Properties in Epitaxial Graphene Grown on SiC. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E2234. [PMID: 33187068 PMCID: PMC7696917 DOI: 10.3390/nano10112234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 11/02/2020] [Accepted: 11/04/2020] [Indexed: 11/17/2022]
Abstract
Graphene distinctive electronic and optical properties have sparked intense interest throughout the scientific community bringing innovation and progress to many sectors of academia and industry. Graphene manufacturing has rapidly evolved since its discovery in 2004. The diverse growth methods of graphene have many comparative advantages in terms of size, shape, quality and cost. Specifically, epitaxial graphene is thermally grown on a silicon carbide (SiC) substrate. This type of graphene is unique due to its coexistence with the SiC underneath which makes the process of transferring graphene layers for devices manufacturing simple and robust. Raman analysis is a sensitive technique extensively used to explore nanocarbon material properties. Indeed, this method has been widely used in graphene studies in fundamental research and application fields. We review the principal Raman scattering processes in SiC substrate and demonstrate epitaxial graphene growth. We have identified the Raman bands signature of graphene for different layers number. The method could be readily adopted to characterize structural and exceptional electrical properties for various epitaxial graphene systems. Particularly, the variation of the charge carrier concentration in epitaxial graphene of different shapes and layers number have been precisely imaged. By comparing the intensity ratio of 2D line and G line-"I2D/IG"-the density of charge across the graphene layers could be monitored. The obtained results were compared to previous electrical measurements. The substrate longitudinal optical phonon coupling "LOOPC" modes have also been examined for several epitaxial graphene layers. The LOOPC of the SiC substrate shows a precise map of the density of charge in epitaxial graphene systems for different graphene layers number. Correlations between the density of charge and particular graphene layer shape such as bubbles have been determined. All experimental probes show a high degree of consistency and efficiency. Our combined studies have revealed novel capacitor effect in diverse epitaxial graphene system. The SiC substrate self-compensates the graphene layer charge without any external doping. We have observed a new density of charge at the graphene-substrate interface. The located capacitor effects at epitaxial graphene-substrate interfaces give rise to an unexpected mini gap in graphene band structure.
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Affiliation(s)
- A. Ben Gouider Trabelsi
- Department of Physics, College of Science, Princess Nourah bint Abdulrahman University, Riyadh PO Box 84428, Saudi Arabia;
| | - F. V. Kusmartsev
- Department of Physics, Loughborough University, Loughborough LE11 3TU, UK; (F.V.K.); (A.K.)
- Micro/Nano Fabrication Laboratory, Microsystem & Terahertz Research Centre of CAEP, Chengdu, China
| | - A. Kusmartseva
- Department of Physics, Loughborough University, Loughborough LE11 3TU, UK; (F.V.K.); (A.K.)
| | - F. H. Alkallas
- Department of Physics, College of Science, Princess Nourah bint Abdulrahman University, Riyadh PO Box 84428, Saudi Arabia;
| | - S. AlFaify
- Department of Physics, Faculty of Sciences, King Khalid University, Abha PO Box 61421, Saudi Arabia; (S.A.); (M.S.)
| | - Mohd Shkir
- Department of Physics, Faculty of Sciences, King Khalid University, Abha PO Box 61421, Saudi Arabia; (S.A.); (M.S.)
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5
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Liu Z, Guo K, Hu G, Shi Z, Li Y, Zhang L, Chen H, Zhang L, Zhou P, Lu H, Lin ML, Liu S, Cheng Y, Liu XL, Xie J, Bi L, Tan PH, Deng L, Qiu CW, Peng B. Observation of nonreciprocal magnetophonon effect in nonencapsulated few-layered CrI 3. SCIENCE ADVANCES 2020; 6:6/43/eabc7628. [PMID: 33097544 PMCID: PMC7608833 DOI: 10.1126/sciadv.abc7628] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 09/03/2020] [Indexed: 05/31/2023]
Abstract
"Magneto-optical" effect refers to a rotation of polarization plane, which has been widely studied in traditional ferromagnetic metal and insulator films and scarcely in two-dimensional layered materials. Here, we uncover a new nonreciprocal magnetophonon Raman scattering effect in ferromagnetic few-layer CrI3 We observed a rotation of the polarization plane of inelastically scattered light between -20o and +60o that are tunable by an out-of-plane magnetic field from -2.5 to 2.5 T. It is experimentally observed that the degree of polarization can be magnetically manipulated between -20 and 85%. This work raises a new magneto-optical phenomenon and could create opportunities of applying two-dimensional ferromagnetic materials in Raman lasing, topological photonics, and magneto-optical modulator for information transport and storage.
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Affiliation(s)
- Zhen Liu
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Kai Guo
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Guangwei Hu
- Department of Electrical and Computer Engineering, National University of Singapore, 117583, Singapore
| | - Zhongtai Shi
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Yue Li
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Linbo Zhang
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Haiyan Chen
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Li Zhang
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Peiheng Zhou
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Haipeng Lu
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Miao-Ling Lin
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083, China
| | - Sizhao Liu
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing 211816, China
| | - Yingchun Cheng
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing 211816, China
| | - Xue Lu Liu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083, China
| | - Jianliang Xie
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Lei Bi
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Ping-Heng Tan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083, China
| | - Longjiang Deng
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, 117583, Singapore.
| | - Bo Peng
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.
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6
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Feng X, Sallis S, Shao YC, Qiao R, Liu YS, Kao LC, Tremsin AS, Hussain Z, Yang W, Guo J, Chuang YD. Disparate Exciton-Phonon Couplings for Zone-Center and Boundary Phonons in Solid-State Graphite. PHYSICAL REVIEW LETTERS 2020; 125:116401. [PMID: 32975957 DOI: 10.1103/physrevlett.125.116401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/26/2020] [Accepted: 07/28/2020] [Indexed: 06/11/2023]
Abstract
The exciton-phonon coupling in highly oriented pyrolytic graphite is studied using resonant inelastic x-ray scattering (RIXS) spectroscopy. With ∼70 meV energy resolution, multiple low energy excitations associated with coupling to phonons can be clearly resolved in the RIXS spectra. Using resonance dependence and the closed form for RIXS cross section without considering the intermediate state mixing of phonon modes, the dimensionless coupling constant g is determined to be 5 and 0.35, corresponding to the coupling strength of 0.42 eV+/-20 meV and 0.20 eV+/-20 meV, for zone center and boundary phonons, respectively. The reduced g value for the zone-boundary phonon may be related to its double resonance nature.
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Affiliation(s)
- Xuefei Feng
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Shawn Sallis
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Yu-Cheng Shao
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of Houston, Houston, Texas 77204, USA
| | - Ruimin Qiao
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Yi-Sheng Liu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Li Cheng Kao
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Anton S Tremsin
- Space Science Laboratory, University of California, Berkeley, California 94720, USA
| | - Zahid Hussain
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Wanli Yang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jinghua Guo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Yi-De Chuang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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7
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Fu W, Zhao X, Wang K, Chen Z, Leng K, Fu D, Song P, Wang H, Deng L, Pennycook SJ, Zhang G, Peng B, Loh KP. An Anomalous Magneto-Optic Effect in Epitaxial Indium Selenide Layers. NANO LETTERS 2020; 20:5330-5338. [PMID: 32501013 DOI: 10.1021/acs.nanolett.0c01704] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Single-phonon modes offer potential applications in quantum phonon optics, but the phonon density of states of most materials consist of mixed contributions from coupled phonons. Here, using theoretical calculations and magneto-Raman measurements, we report two single-phonon vibration modes originating from the breathing and opposite out-of-plane vibrations of InSe layers. These single-phonon vibrations exhibit an anticorrelated scattering rotations of the polarization axis under an applied vertical magnetic field; such an anomalous magneto-optical behavior is due to the reverse bond polarizations of two quantum atomic vibrations, which induce different symmetry for the corresponding Raman selection rules. A 180° (+90° and -90°) integrated scattering rotation angle of two single-phonon modes was achieved when the magnetic field was swept from 0 to 6 T. This work demonstrates new ways to manipulate the magneto-optic effect through phonon polarity-based symmetry control and opens avenues for exploring single-phonon-vibration-based nanomechanical oscillators and magneto-phonon-coupled physics.
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Affiliation(s)
- Wei Fu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
| | - Xiaoxu Zhao
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - Ke Wang
- Xidian University, No. 2 Taibai Road, Xi'an, 710071 Shaanxi Province, China
- Institute of High Performance Computing, A*STAR, Singapore 138632, Singapore
| | - Zhi Chen
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Kai Leng
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Deyi Fu
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
| | - Peng Song
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Hai Wang
- Xidian University, No. 2 Taibai Road, Xi'an, 710071 Shaanxi Province, China
| | - Longjiang Deng
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Stephen J Pennycook
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - Gang Zhang
- Institute of High Performance Computing, A*STAR, Singapore 138632, Singapore
| | - Bo Peng
- National Engineering Research Center of Electromagnetic Radiation Control Materials, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
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8
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Wu Z, Zhang X, Das A, Liu J, Zou Z, Zhang Z, Xia Y, Zhao P, Wang H. Step-by-step monitoring of CVD-graphene during wet transfer by Raman spectroscopy. RSC Adv 2019; 9:41447-41452. [PMID: 35541595 PMCID: PMC9076457 DOI: 10.1039/c9ra09268d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 12/08/2019] [Indexed: 11/26/2022] Open
Abstract
Transfer acts as a crucial bridge between the chemical vapor deposition (CVD) synthesis of large-scale graphene and its applications, but the quality evolution of a graphene film during transfer remains unclear. Here we use scanning Raman spectroscopy to monitor as-grown graphene during each step of wet transfer including floating on etchant solution, loaded onto a target substrate, and with additional annealing. Results show that the etchant solution results in strong compressive strain and p-type doping to floating graphene, but both are significantly reduced after the sample is loaded and rinsed especially for the doping. An annealing treatment increases the compressive strain in graphene but hardly its doping level. Moreover, when a poly(methyl methacrylate) (PMMA) layer is used to assist the transfer, it does not only increase the p-type doping of floating graphene but also lowers the crystalline quality of annealed graphene. Therefore, to obtain graphene with better quality, besides the attempts of improving CVD synthesis for its larger domain sizes, universal and easy-to-use polymer-free transfer techniques must be developed as well. The quality evolution of as-grown graphene during wet transfer from Cu to SiO2/Si substrate is investigated by Raman spectroscopy and the relavant factors during this process are identified.![]()
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Affiliation(s)
- Zehao Wu
- Center for X-Mechanics and Institute of Applied Mechanics, Zhejiang University Hangzhou 310012 P. R. China
| | - Xuewei Zhang
- Center for X-Mechanics and Institute of Applied Mechanics, Zhejiang University Hangzhou 310012 P. R. China
| | - Atanu Das
- Center for X-Mechanics and Institute of Applied Mechanics, Zhejiang University Hangzhou 310012 P. R. China
| | - Jinglan Liu
- Center for X-Mechanics and Institute of Applied Mechanics, Zhejiang University Hangzhou 310012 P. R. China
| | - Zhenxing Zou
- Center for X-Mechanics and Institute of Applied Mechanics, Zhejiang University Hangzhou 310012 P. R. China
| | - Zilong Zhang
- Center for X-Mechanics and Institute of Applied Mechanics, Zhejiang University Hangzhou 310012 P. R. China
| | - Yang Xia
- Institute of Microelectronics, Chinese Academy of Sciences Beijing 100029 China
| | - Pei Zhao
- Center for X-Mechanics and Institute of Applied Mechanics, Zhejiang University Hangzhou 310012 P. R. China
| | - Hongtao Wang
- Center for X-Mechanics and Institute of Applied Mechanics, Zhejiang University Hangzhou 310012 P. R. China
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9
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Sonntag J, Reichardt S, Wirtz L, Beschoten B, Katsnelson MI, Libisch F, Stampfer C. Impact of Many-Body Effects on Landau Levels in Graphene. PHYSICAL REVIEW LETTERS 2018; 120:187701. [PMID: 29775369 DOI: 10.1103/physrevlett.120.187701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Indexed: 06/08/2023]
Abstract
We present magneto-Raman spectroscopy measurements on suspended graphene to investigate the charge carrier density-dependent electron-electron interaction in the presence of Landau levels. Utilizing gate-tunable magnetophonon resonances, we extract the charge carrier density dependence of the Landau level transition energies and the associated effective Fermi velocity v_{F}. In contrast to the logarithmic divergence of v_{F} at zero magnetic field, we find a piecewise linear scaling of v_{F} as a function of the charge carrier density, due to a magnetic-field-induced suppression of the long-range Coulomb interaction. We quantitatively confirm our experimental findings by performing tight-binding calculations on the level of the Hartree-Fock approximation, which also allow us to estimate an excitonic binding energy of ≈6 meV contained in the experimentally extracted Landau level transitions energies.
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Affiliation(s)
- J Sonntag
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - S Reichardt
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany
- Physics and Materials Science Research Unit, University of Luxembourg, L-1511 Luxembourg, Luxembourg
| | - L Wirtz
- Physics and Materials Science Research Unit, University of Luxembourg, L-1511 Luxembourg, Luxembourg
| | - B Beschoten
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany
| | - M I Katsnelson
- Institute for Molecules and Materials, Radboud University, 6525AJ Nijmegen, Netherlands
| | - F Libisch
- Institute for Theoretical Physics, Vienna University of Technology, 1040 Vienna, Austria
| | - C Stampfer
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
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10
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Wu JB, Lin ML, Cong X, Liu HN, Tan PH. Raman spectroscopy of graphene-based materials and its applications in related devices. Chem Soc Rev 2018; 47:1822-1873. [PMID: 29368764 DOI: 10.1039/c6cs00915h] [Citation(s) in RCA: 522] [Impact Index Per Article: 87.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Graphene-based materials exhibit remarkable electronic, optical, and mechanical properties, which has resulted in both high scientific interest and huge potential for a variety of applications. Furthermore, the family of graphene-based materials is growing because of developments in preparation methods. Raman spectroscopy is a versatile tool to identify and characterize the chemical and physical properties of these materials, both at the laboratory and mass-production scale. This technique is so important that most of the papers published concerning these materials contain at least one Raman spectrum. Thus, here, we systematically review the developments in Raman spectroscopy of graphene-based materials from both fundamental research and practical (i.e., device applications) perspectives. We describe the essential Raman scattering processes of the entire first- and second-order modes in intrinsic graphene. Furthermore, the shear, layer-breathing, G and 2D modes of multilayer graphene with different stacking orders are discussed. Techniques to determine the number of graphene layers, to probe resonance Raman spectra of monolayer and multilayer graphenes and to obtain Raman images of graphene-based materials are also presented. The extensive capabilities of Raman spectroscopy for the investigation of the fundamental properties of graphene under external perturbations are described, which have also been extended to other graphene-based materials, such as graphene quantum dots, carbon dots, graphene oxide, nanoribbons, chemical vapor deposition-grown and SiC epitaxially grown graphene flakes, composites, and graphene-based van der Waals heterostructures. These fundamental properties have been used to probe the states, effects, and mechanisms of graphene materials present in the related heterostructures and devices. We hope that this review will be beneficial in all the aspects of graphene investigations, from basic research to material synthesis and device applications.
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Affiliation(s)
- Jiang-Bin Wu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
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11
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Chen ZG, Wang L, Song Y, Lu X, Luo H, Zhang C, Dai P, Yin Z, Haule K, Kotliar G. Two-Dimensional Massless Dirac Fermions in Antiferromagnetic AFe_{2}As_{2} (A=Ba,Sr). PHYSICAL REVIEW LETTERS 2017; 119:096401. [PMID: 28949552 DOI: 10.1103/physrevlett.119.096401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Indexed: 06/07/2023]
Abstract
We report infrared studies of AFe_{2}As_{2} (A=Ba, Sr), two representative parent compounds of iron-arsenide superconductors, at magnetic fields (B) up to 17.5 T. Optical transitions between Landau levels (LLs) were observed in the antiferromagnetic states of these two parent compounds. Our observation of a sqrt[B] dependence of the LL transition energies, the zero-energy intercepts at B=0 T under the linear extrapolations of the transition energies and the energy ratio (∼2.4) between the observed LL transitions, combined with the linear band dispersions in two-dimensional (2D) momentum space obtained by theoretical calculations, demonstrates the existence of massless Dirac fermions in the antiferromagnet BaFe_{2}As_{2}. More importantly, the observed dominance of the zeroth-LL-related absorption features and the calculated bands with extremely weak dispersions along the momentum direction k_{z} indicate that massless Dirac fermions in BaFe_{2}As_{2} are 2D. Furthermore, we find that the total substitution of the barium atoms in BaFe_{2}As_{2} by strontium atoms not only maintains 2D massless Dirac fermions in this system, but also enhances their Fermi velocity, which supports that the Dirac points in iron-arsenide parent compounds are topologically protected.
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Affiliation(s)
- Zhi-Guo Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Luyang Wang
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
- Sate Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-Sen University, Guangzhou 510275, China
| | - Yu Song
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Xingye Lu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Huiqian Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Chenglin Zhang
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Zhiping Yin
- Center of Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Kristjan Haule
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- DMFT-MatDeLab Center, Upton, New York 11973, USA
| | - Gabriel Kotliar
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- DMFT-MatDeLab Center, Upton, New York 11973, USA
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12
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Riccardi E, Méasson MA, Cazayous M, Sacuto A, Gallais Y. Gate-Dependent Electronic Raman Scattering in Graphene. PHYSICAL REVIEW LETTERS 2016; 116:066805. [PMID: 26919008 DOI: 10.1103/physrevlett.116.066805] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Indexed: 06/05/2023]
Abstract
We report the direct observation of polarization resolved electronic Raman scattering in a gated monolayer graphene device. The evolution of the electronic Raman scattering spectra with gate voltage and its polarization dependence are in full agreement with theoretical expectations for nonresonant Raman processes involving interband electron-hole excitations across the Dirac cone. We further show that the spectral dependence of the electronic Raman scattering signal can be simply described by the dynamical polarizability of graphene in the long wavelength limit. The possibility to directly observe Dirac fermion excitations in graphene opens the way to promising Raman investigations of electronic properties of graphene and other 2D crystals.
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Affiliation(s)
- E Riccardi
- Laboratoire Matériaux et Phénoménes Quantiques (UMR 7162 CNRS), Université Paris Diderot-Paris 7, Bâtiment Condorcet, 75205 Paris Cedex 13, France
| | - M-A Méasson
- Laboratoire Matériaux et Phénoménes Quantiques (UMR 7162 CNRS), Université Paris Diderot-Paris 7, Bâtiment Condorcet, 75205 Paris Cedex 13, France
| | - M Cazayous
- Laboratoire Matériaux et Phénoménes Quantiques (UMR 7162 CNRS), Université Paris Diderot-Paris 7, Bâtiment Condorcet, 75205 Paris Cedex 13, France
| | - A Sacuto
- Laboratoire Matériaux et Phénoménes Quantiques (UMR 7162 CNRS), Université Paris Diderot-Paris 7, Bâtiment Condorcet, 75205 Paris Cedex 13, France
| | - Y Gallais
- Laboratoire Matériaux et Phénoménes Quantiques (UMR 7162 CNRS), Université Paris Diderot-Paris 7, Bâtiment Condorcet, 75205 Paris Cedex 13, France
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13
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Neumann C, Reichardt S, Venezuela P, Drögeler M, Banszerus L, Schmitz M, Watanabe K, Taniguchi T, Mauri F, Beschoten B, Rotkin SV, Stampfer C. Raman spectroscopy as probe of nanometre-scale strain variations in graphene. Nat Commun 2015; 6:8429. [PMID: 26416349 PMCID: PMC4598719 DOI: 10.1038/ncomms9429] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 08/21/2015] [Indexed: 12/23/2022] Open
Abstract
Confocal Raman spectroscopy has emerged as a major, versatile workhorse for the non-invasive characterization of graphene. Although it is successfully used to determine the number of layers, the quality of edges, and the effects of strain, doping and disorder, the nature of the experimentally observed broadening of the most prominent Raman 2D line has remained unclear. Here we show that the observed 2D line width contains valuable information on strain variations in graphene on length scales far below the laser spot size, that is, on the nanometre-scale. This finding is highly relevant as it has been shown recently that such nanometre-scaled strain variations limit the carrier mobility in high-quality graphene devices. Consequently, the 2D line width is a good and easily accessible quantity for classifying the crystalline quality, nanometre-scale flatness as well as local electronic properties of graphene, all important for future scientific and industrial applications. Raman spectroscopy has become an invaluable tool for graphene characterisation, yet the nature of the broadening of the Raman 2D line remains unclear. Here, Stampfer et al. show that the Raman 2D line width is a measure of nanometre-scale strain variations in graphene on insulating substrates.
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Affiliation(s)
- C Neumann
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.,Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
| | - S Reichardt
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - P Venezuela
- Instituto de Fsica, Universidade Federal Fluminense, Niterói, 24210-346 Rio de Janeiro, Brazil
| | - M Drögeler
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - L Banszerus
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - M Schmitz
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - K Watanabe
- National Institute for Materials Science,1-1 Namiki, Tsukuba 305-0044, Japan
| | - T Taniguchi
- National Institute for Materials Science,1-1 Namiki, Tsukuba 305-0044, Japan
| | - F Mauri
- IMPMC, UMR CNRS 7590, Sorbonne Universités-UPMC Univ. Paris 06, MNHN, IRD, 4 Place Jussieu, Paris 75005, France
| | - B Beschoten
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - S V Rotkin
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.,Department of Physics and Center for Advanced Materials and Nanotechnology, Lehigh University, Bethlehem, Pennsylvania 18015, USA
| | - C Stampfer
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany.,Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
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14
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Ferrari AC, Bonaccorso F, Fal'ko V, Novoselov KS, Roche S, Bøggild P, Borini S, Koppens FHL, Palermo V, Pugno N, Garrido JA, Sordan R, Bianco A, Ballerini L, Prato M, Lidorikis E, Kivioja J, Marinelli C, Ryhänen T, Morpurgo A, Coleman JN, Nicolosi V, Colombo L, Fert A, Garcia-Hernandez M, Bachtold A, Schneider GF, Guinea F, Dekker C, Barbone M, Sun Z, Galiotis C, Grigorenko AN, Konstantatos G, Kis A, Katsnelson M, Vandersypen L, Loiseau A, Morandi V, Neumaier D, Treossi E, Pellegrini V, Polini M, Tredicucci A, Williams GM, Hong BH, Ahn JH, Kim JM, Zirath H, van Wees BJ, van der Zant H, Occhipinti L, Di Matteo A, Kinloch IA, Seyller T, Quesnel E, Feng X, Teo K, Rupesinghe N, Hakonen P, Neil SRT, Tannock Q, Löfwander T, Kinaret J. Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems. NANOSCALE 2015; 7:4598-810. [PMID: 25707682 DOI: 10.1039/c4nr01600a] [Citation(s) in RCA: 985] [Impact Index Per Article: 109.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.
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Affiliation(s)
- Andrea C Ferrari
- Cambridge Graphene Centre, University of Cambridge, Cambridge, CB3 0FA, UK.
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15
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Neumann C, Reichardt S, Drögeler M, Terrés B, Watanabe K, Taniguchi T, Beschoten B, Rotkin SV, Stampfer C. Low B field magneto-phonon resonances in single-layer and bilayer graphene. NANO LETTERS 2015; 15:1547-1552. [PMID: 25646665 DOI: 10.1021/nl5038825] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Many-body effects resulting from strong electron-electron and electron-phonon interactions play a significant role in graphene physics. We report on their manifestation in low B field magneto-phonon resonances in high-quality exfoliated single-layer and bilayer graphene encapsulated in hexagonal boron nitride. These resonances allow us to extract characteristic effective Fermi velocities, as high as 1.20 × 10(6) m/s, for the observed "dressed" Landau level transitions, as well as the broadening of the resonances, which increases with the Landau level index.
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Affiliation(s)
- Christoph Neumann
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University , 52074 Aachen, Germany
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16
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Mitsui T. Compact and high-efficiency device for Raman scattering measurement using optical fibers. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:113111. [PMID: 25430102 DOI: 10.1063/1.4902342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We describe the design and development of a high-efficiency optical measurement device for operation within the small bore of a high-power magnet at low temperature. For the high-efficiency measurement of light emitted from this small region, we designed a compact confocal optics with lens focusing and tilting systems, and used a piezodriven translation stage that allows micron-scale focus control of the sample position. We designed a measurement device that uses 10 m-long optical fibers in order to avoid the influence of mechanical vibration and magnetic field leakage of high-power magnets, and we also describe a technique for minimizing the fluorescence signal of optical fibers. The operation of the device was confirmed by Raman scattering measurements of monolayer graphene on quartz glass with a high signal-to-noise ratio.
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Affiliation(s)
- Tadashi Mitsui
- Surface Physics and Structure Unit, Advanced Key Technologies Division, National Institute for Materials Science, Sakura 3-13, Tsukuba 305-0003, Japan
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17
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Berciaud S, Potemski M, Faugeras C. Probing electronic excitations in mono- to pentalayer graphene by micro magneto-Raman spectroscopy. NANO LETTERS 2014; 14:4548-4553. [PMID: 24955484 DOI: 10.1021/nl501578m] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We probe electronic excitations between Landau levels in freestanding N-layer graphene over a broad energy range, with unprecedented spectral and spatial resolution, using micro magneto-Raman scattering spectroscopy. A characteristic evolution of electronic bands in up to five Bernal-stacked graphene layers is evidenced and shown to remarkably follow a simple theoretical approach, based on an effective bilayer model. (N > 3)-layer graphenes appear as appealing candidates in the quest for novel phenomena, particularly in the quantum Hall effect regime. Our work paves the way toward minimally invasive investigations of magneto-excitons in other emerging low-dimensional systems, with a spatial resolution down to 1 μm.
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Affiliation(s)
- Stéphane Berciaud
- Institut de Physique et Chimie des Matériaux de Strasbourg and NIE, UMR 7504, Université de Strasbourg and CNRS , 23 rue du Lœss, BP43, 67034 Strasbourg Cedex 2, France
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18
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Wendler F, Knorr A, Malic E. Carrier multiplication in graphene under Landau quantization. Nat Commun 2014; 5:3703. [DOI: 10.1038/ncomms4703] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 03/21/2014] [Indexed: 11/09/2022] Open
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19
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Leszczynski P, Han Z, Nicolet AAL, Piot BA, Kossacki P, Orlita M, Bouchiat V, Basko DM, Potemski M, Faugeras C. Electrical switch to the resonant magneto-phonon effect in graphene. NANO LETTERS 2014; 14:1460-1466. [PMID: 24490748 DOI: 10.1021/nl404588g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report a comprehensive study of the tuning with electric fields of the resonant magneto-exciton optical phonon coupling in gated graphene. For magnetic fields around B ∼ 25 T that correspond to the range of the fundamental magneto-phonon resonance, the electron-phonon coupling can be switched on and off by tuning the position of the Fermi level in order to Pauli block the two fundamental inter-Landau level excitations. The effects of such a profound change in the electronic excitation spectrum are traced through investigations of the optical phonon response in polarization resolved magneto-Raman scattering experiments. We report on the observation of a splitting of the phonon feature with satellite peaks developing at particular values of the Landau level filling factor on the low or on the high energy side of the phonon, depending on the relative energy of the discrete electronic excitation and of the optical phonon. Shifts of the phonon energy as large as ±60 cm(-1) are observed close to the resonance. The intraband electronic excitation, the cyclotron resonance, is shown to play a relevant role in the observed spectral evolution of the phonon response.
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20
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Rémi S, Goldberg BB, Swan AK. Charge tuning of nonresonant magnetoexciton phonon interactions in graphene. PHYSICAL REVIEW LETTERS 2014; 112:056803. [PMID: 24580621 DOI: 10.1103/physrevlett.112.056803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Indexed: 06/03/2023]
Abstract
Far from resonance, the coupling of the G-band phonon to magnetoexcitons in single layer graphene displays kinks and splittings versus filling factor that are well described by Pauli blocking and unblocking of inter- and intra-Landau level transitions. We explore the nonresonant electron-phonon coupling by high-magnetic field Raman scattering while electrostatic tuning of the carrier density controls the filling factor. We show qualitative and quantitative agreement between spectra and a linearized model of electron-phonon interactions in magnetic fields. The splitting is caused by dichroism of left- and right-handed circular polarized light due to lifting of the G-band phonon degeneracy, and the piecewise linear slopes are caused by the linear occupancy of sequential Landau levels versus ν.
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Affiliation(s)
- Sebastian Rémi
- Boston University, Department of Physics, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
| | - Bennett B Goldberg
- Boston University, Department of Physics, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA and Boston University, Department of Electrical and Computer Engineering, Boston, Massachusetts 02215, USA and Boston University, Photonics Center, 8 St. Mary's St, Boston, Massachusetts 02215, USA
| | - Anna K Swan
- Boston University, Department of Physics, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA and Boston University, Department of Electrical and Computer Engineering, Boston, Massachusetts 02215, USA and Boston University, Photonics Center, 8 St. Mary's St, Boston, Massachusetts 02215, USA
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21
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Kim Y, Poumirol JM, Lombardo A, Kalugin NG, Georgiou T, Kim YJ, Novoselov KS, Ferrari AC, Kono J, Kashuba O, Fal'ko VI, Smirnov D. Measurement of filling-factor-dependent magnetophonon resonances in graphene using Raman spectroscopy. PHYSICAL REVIEW LETTERS 2013; 110:227402. [PMID: 23767746 DOI: 10.1103/physrevlett.110.227402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Indexed: 06/02/2023]
Abstract
We perform polarization-resolved Raman spectroscopy on graphene in magnetic fields up to 45 T. This reveals a filling-factor-dependent, multicomponent anticrossing structure of the Raman G peak, resulting from magnetophonon resonances between magnetoexcitons and E(2g) phonons. This is explained with a model of Raman scattering taking into account the effects of spatially inhomogeneous carrier densities and strain. Random fluctuations of strain-induced pseudomagnetic fields lead to increased scattering intensity inside the anticrossing gap, consistent with the experiments.
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Affiliation(s)
- Y Kim
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
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22
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Ferrari AC, Basko DM. Raman spectroscopy as a versatile tool for studying the properties of graphene. NATURE NANOTECHNOLOGY 2013; 8:235-46. [PMID: 23552117 DOI: 10.1038/nnano.2013.46] [Citation(s) in RCA: 2227] [Impact Index Per Article: 202.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Accepted: 03/01/2013] [Indexed: 05/19/2023]
Abstract
Raman spectroscopy is an integral part of graphene research. It is used to determine the number and orientation of layers, the quality and types of edge, and the effects of perturbations, such as electric and magnetic fields, strain, doping, disorder and functional groups. This, in turn, provides insight into all sp(2)-bonded carbon allotropes, because graphene is their fundamental building block. Here we review the state of the art, future directions and open questions in Raman spectroscopy of graphene. We describe essential physical processes whose importance has only recently been recognized, such as the various types of resonance at play, and the role of quantum interference. We update all basic concepts and notations, and propose a terminology that is able to describe any result in literature. We finally highlight the potential of Raman spectroscopy for layered materials other than graphene.
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Affiliation(s)
- Andrea C Ferrari
- Cambridge Graphene Centre, Cambridge University, 9 JJ Thomson Avenue, Cambridge CB3 OFA, UK.
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23
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Zhu J, Badalyan SM, Peeters FM. Electron-phonon bound states in graphene in a perpendicular magnetic field. PHYSICAL REVIEW LETTERS 2012; 109:256602. [PMID: 23368485 DOI: 10.1103/physrevlett.109.256602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Indexed: 06/01/2023]
Abstract
The spectrum of electron-phonon complexes in monolayer graphene is investigated in the presence of a perpendicular quantizing magnetic field. Despite the small electron-phonon coupling, usual perturbation theory is inapplicable for the calculation of the scattering amplitude near the threshold of optical phonon emission. Our findings, beyond perturbation theory, show that the true spectrum near the phonon-emission threshold is completely governed by new branches, corresponding to bound states of an electron and an optical phonon with a binding energy of the order of αω(0), where α is the electron-phonon coupling and ω(0) the phonon energy.
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Affiliation(s)
- J Zhu
- Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium.
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24
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Faugeras C, Amado M, Kossacki P, Orlita M, Kühne M, Nicolet AAL, Latyshev YI, Potemski M. Magneto-Raman scattering of graphene on graphite: electronic and phonon excitations. PHYSICAL REVIEW LETTERS 2011; 107:036807. [PMID: 21838392 DOI: 10.1103/physrevlett.107.036807] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Indexed: 05/31/2023]
Abstract
Magneto-Raman-scattering experiments from the surface of graphite reveal novel features associated to purely electronic excitations which are observed in addition to phonon-mediated resonances. Graphene-like and graphite domains are identified through experiments with ∼1 μm spatial resolution performed in magnetic fields up to 32 T. Polarization resolved measurements emphasize the characteristic selection rules for electronic transitions in graphene. Graphene on graphite displays the unexpected hybridization between optical phonon and symmetric across the Dirac point inter Landau level transitions. The results open new experimental possibilities--to use light scattering methods in studies of graphene under quantum Hall effect conditions.
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Affiliation(s)
- C Faugeras
- LNCMI, UPR 3228, CNRS-UJF-UPS-INSA, 38042 Grenoble, France
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25
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Yan J, Goler S, Rhone TD, Han M, He R, Kim P, Pellegrini V, Pinczuk A. Observation of magnetophonon resonance of Dirac fermions in graphite. PHYSICAL REVIEW LETTERS 2010; 105:227401. [PMID: 21231420 DOI: 10.1103/physrevlett.105.227401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Indexed: 05/30/2023]
Abstract
Coherent coupling of Dirac fermion magnetoexcitons with an optical phonon is observed in graphite as marked magnetic-field dependent splittings and anticrossing behavior of the two coupled modes. The sharp magnetophonon resonance occurs in regions of the graphite sample with properties of superior single-layer graphene having enhanced lifetimes of Dirac fermions. The greatly reduced carrier broadening to values below the graphene electron-phonon coupling constant explains the appearance of sharp resonances that reveal a fundamental interaction of Dirac fermions.
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Affiliation(s)
- Jun Yan
- Department of Physics, Columbia University, New York, New York 10027, USA
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Attaccalite C, Wirtz L, Lazzeri M, Mauri F, Rubio A. Doped graphene as tunable electron-phonon coupling material. NANO LETTERS 2010; 10:1172-1176. [PMID: 20222744 DOI: 10.1021/nl9034626] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We present a new way to tune the electron-phonon coupling (EPC) in graphene by changing the deformation potential with electron/hole doping. We show the EPC for highest optical branch at the high symmetry point K acquires a strong dependency on the doping level due to electron-electron correlation not accounted in mean-field approaches. Such a dependency influences the dispersion (with respect to the laser energy) of the Raman D and 2D lines and the splitting of the 2D peak in multilayer graphene. Finally this doping dependence opens the possibility to construct tunable electronic devices through external control of the EPC.
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Affiliation(s)
- Claudio Attaccalite
- ETSF Scientific Development Centre, Departamento Fisica de Materiales, Universidad del Pais Vasco, San Sebastian, Spain.
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