1
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Wehmeier L, Yu SJ, Chen X, Mayer RA, Xiong L, Yao H, Jiang Y, Hu J, Janzen E, Edgar JH, Zheng X, Heinz TF, Basov DN, Homes CC, Hu G, Carr GL, Liu M, Fan JA. Tunable Phonon Polariton Hybridization in a Van der Waals Hetero-Bicrystal. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2401349. [PMID: 38657644 DOI: 10.1002/adma.202401349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 04/05/2024] [Indexed: 04/26/2024]
Abstract
Phonon polaritons, the hybrid quasiparticles resulting from the coupling of photons and lattice vibrations, have gained significant attention in the field of layered van der Waals heterostructures. Particular interest has been paid to hetero-bicrystals composed of molybdenum oxide (MoO3) and hexagonal boron nitride (hBN), which feature polariton dispersion tailorable via avoided polariton mode crossings. In this work, the polariton eigenmodes in MoO3-hBN hetero-bicrystals self-assembled on ultrasmooth gold are systematically studied using synchrotron infrared nanospectroscopy. It is experimentally demonstrated that the spectral gap in bicrystal dispersion and corresponding regimes of negative refraction can be tuned by material layer thickness, and these results are quantitatively matched with a simple analytic model. Polaritonic cavity modes and polariton propagation along "forbidden" directions are also investigated in microscale bicrystals, which arise from the finite in-plane dimension of the synthesized MoO3 micro-ribbons. The findings shed light on the unique dispersion properties of polaritons in van der Waals heterostructures and pave the way for applications leveraging deeply sub-wavelength mid-infrared light-matter interactions.
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Affiliation(s)
- Lukas Wehmeier
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Shang-Jie Yu
- Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Xinzhong Chen
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Rafael A Mayer
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Langlang Xiong
- Nanyang Technological University, School of Electrical and Electronic Engineering, Singapore, 637371
| | - Helen Yao
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Yue Jiang
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Jenny Hu
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Eli Janzen
- Tim Taylor Department of Chemical Engineering, Durland Hall, Kansas State University, Manhattan, KS, 66506, USA
| | - James H Edgar
- Tim Taylor Department of Chemical Engineering, Durland Hall, Kansas State University, Manhattan, KS, 66506, USA
| | - Xiaolin Zheng
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Tony F Heinz
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - D N Basov
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Christopher C Homes
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Guangwei Hu
- Nanyang Technological University, School of Electrical and Electronic Engineering, Singapore, 637371
| | - G Lawrence Carr
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Mengkun Liu
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Jonathan A Fan
- Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA
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2
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Choi H, Song YE, Park D, Park C, Park BK, Son SU, Lim J, Chung TM. Germanium and Tin Precursors for Chalcogenide Materials Containing N-Alkoxy Thioamide Ligands. ACS OMEGA 2024; 9:28707-28714. [PMID: 38973851 PMCID: PMC11223241 DOI: 10.1021/acsomega.4c03019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 06/05/2024] [Accepted: 06/07/2024] [Indexed: 07/09/2024]
Abstract
This study describes the synthesis of germanium and tin complexes Ge(mdpaS)2 (1), Ge(edpaS)2 (2), Ge(bdpaS)2 (3), Ge(empaS)2 (4), Sn(mdpaS)2 (5), Sn(edpaS)2 (6), Sn(bdpaS)2 (7), and Sn(empaS)2 (8) (mdpaSH = (Z)-N-methoxy-2,2-dimethylpropanimidothioic acid; edpaSH = (Z)-N-ethoxy-2,2-dimethylpropanimidothioic acid; bdpaSH = (Z)-N-(tert-butoxy)-2,2-dimethylpropanimidothioic acid; empaSH = (Z)-N-ethoxy-2-methylpropanimidothioic acid), using newly designed N-alkoxy thioamide ligands as precursors for metal chalcogenide materials. All complexes were characterized using various analytical techniques, and the single-crystal structures of complexes 5 and 7 revealed a distorted seesaw geometry in the monomeric SnL2 form. Thermogravimetric (TG) curves showed differences between Ge compounds, which exhibited single-step weight losses, and Sn compounds, which exhibited multistep weight losses. As a result, we suggest that the synthesized complexes 1-8 are potential precursors for group IV metal chalcogenide materials.
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Affiliation(s)
- Heenang Choi
- Thin
Film Materials Research Center, Korea Research
Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, Republic of Korea
- Department
of Chemistry, Sungkyunkwan University (SKKU), 2066 Seobu-ro,
Jangan-gu, Suwon-si, Gyeonggi-do 16419, Republic
of Korea
| | - Young Eun Song
- Thin
Film Materials Research Center, Korea Research
Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, Republic of Korea
- Department
of Chemical Convergence Materials, University
of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic
of Korea
| | - Dongseong Park
- Thin
Film Materials Research Center, Korea Research
Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, Republic of Korea
| | - Chanwoo Park
- Thin
Film Materials Research Center, Korea Research
Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, Republic of Korea
| | - Bo Keun Park
- Thin
Film Materials Research Center, Korea Research
Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, Republic of Korea
- Department
of Chemical Convergence Materials, University
of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic
of Korea
| | - Seung Uk Son
- Department
of Chemistry, Sungkyunkwan University (SKKU), 2066 Seobu-ro,
Jangan-gu, Suwon-si, Gyeonggi-do 16419, Republic
of Korea
| | - Jongsun Lim
- Thin
Film Materials Research Center, Korea Research
Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, Republic of Korea
| | - Taek-Mo Chung
- Thin
Film Materials Research Center, Korea Research
Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, Republic of Korea
- Department
of Chemical Convergence Materials, University
of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic
of Korea
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3
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Xu R, Crassee I, Bechtel HA, Zhou Y, Bercher A, Korosec L, Rischau CW, Teyssier J, Crust KJ, Lee Y, Gilbert Corder SN, Li J, Dionne JA, Hwang HY, Kuzmenko AB, Liu Y. Highly confined epsilon-near-zero and surface phonon polaritons in SrTiO 3 membranes. Nat Commun 2024; 15:4743. [PMID: 38834672 DOI: 10.1038/s41467-024-47917-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 04/12/2024] [Indexed: 06/06/2024] Open
Abstract
Recent theoretical studies have suggested that transition metal perovskite oxide membranes can enable surface phonon polaritons in the infrared range with low loss and much stronger subwavelength confinement than bulk crystals. Such modes, however, have not been experimentally observed so far. Here, using a combination of far-field Fourier-transform infrared (FTIR) spectroscopy and near-field synchrotron infrared nanospectroscopy (SINS) imaging, we study the phonon polaritons in a 100 nm thick freestanding crystalline membrane of SrTiO3 transferred on metallic and dielectric substrates. We observe a symmetric-antisymmetric mode splitting giving rise to epsilon-near-zero and Berreman modes as well as highly confined (by a factor of 10) propagating phonon polaritons, both of which result from the deep-subwavelength thickness of the membranes. Theoretical modeling based on the analytical finite-dipole model and numerical finite-difference methods fully corroborate the experimental results. Our work reveals the potential of oxide membranes as a promising platform for infrared photonics and polaritonics.
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Affiliation(s)
- Ruijuan Xu
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27606, USA
| | - Iris Crassee
- Department of Quantum Matter Physics, University of Geneva, 1211, Geneva, Switzerland
| | - Hans A Bechtel
- Advanced Light Source Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yixi Zhou
- Department of Quantum Matter Physics, University of Geneva, 1211, Geneva, Switzerland
- Beijing Key Laboratory of Nano-Photonics and Nano-Structure (NPNS), Department of Physics, Capital Normal University, Beijing, China
| | - Adrien Bercher
- Department of Quantum Matter Physics, University of Geneva, 1211, Geneva, Switzerland
| | - Lukas Korosec
- Department of Quantum Matter Physics, University of Geneva, 1211, Geneva, Switzerland
| | - Carl Willem Rischau
- Department of Quantum Matter Physics, University of Geneva, 1211, Geneva, Switzerland
| | - Jérémie Teyssier
- Department of Quantum Matter Physics, University of Geneva, 1211, Geneva, Switzerland
| | - Kevin J Crust
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Yonghun Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | | | - Jiarui Li
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Jennifer A Dionne
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Alexey B Kuzmenko
- Department of Quantum Matter Physics, University of Geneva, 1211, Geneva, Switzerland.
| | - Yin Liu
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27606, USA.
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4
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Pogna EAA, Pistore V, Viti L, Li L, Davies AG, Linfield EH, Vitiello MS. Near-field detection of gate-tunable anisotropic plasmon polaritons in black phosphorus at terahertz frequencies. Nat Commun 2024; 15:2373. [PMID: 38490988 PMCID: PMC10943022 DOI: 10.1038/s41467-024-45264-5] [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: 10/16/2023] [Accepted: 01/18/2024] [Indexed: 03/18/2024] Open
Abstract
Polaritons in two-dimensional layered crystals offer an effective solution to confine, enhance and manipulate terahertz (THz) frequency electromagnetic waves at the nanoscale. Recently, strong THz field confinement has been achieved in a graphene-insulator-metal structure, exploiting THz plasmon polaritons (PPs) with strongly reduced wavelength (λp ≈ λ0/66) compared to the photon wavelength λ0. However, graphene PPs propagate isotropically, complicating the directional control of the THz field, which, on the contrary, can be achieved exploiting anisotropic layered crystals, such as orthorhombic black-phosphorus. Here, we detect PPs, at THz frequencies, in hBN-encapsulated black phosphorus field effect transistors through THz near-field photocurrent nanoscopy. The real-space mapping of the thermoelectrical near-field photocurrents reveals deeply sub-wavelength THz PPs (λp ≈ λ0/76), with dispersion tunable by electrostatic control of the carrier density. The in-plane anisotropy of the dielectric response results into anisotropic polariton propagation along the armchair and zigzag crystallographic axes of black-phosphorus. The achieved directional subwavelength light confinement makes this material system a versatile platform for sensing and quantum technology based on nonlinear optics.
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Affiliation(s)
- Eva A A Pogna
- NEST, CNR - Istituto Nanoscienze and Scuola Normale Superiore, P. San Silvestro 12, 56127, Pisa, Italy.
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Valentino Pistore
- NEST, CNR - Istituto Nanoscienze and Scuola Normale Superiore, P. San Silvestro 12, 56127, Pisa, Italy
| | - Leonardo Viti
- NEST, CNR - Istituto Nanoscienze and Scuola Normale Superiore, P. San Silvestro 12, 56127, Pisa, Italy
| | - Lianhe Li
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - A Giles Davies
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Edmund H Linfield
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Miriam S Vitiello
- NEST, CNR - Istituto Nanoscienze and Scuola Normale Superiore, P. San Silvestro 12, 56127, Pisa, Italy.
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5
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Wehmeier L, Liu M, Park S, Jang H, Basov DN, Homes CC, Carr GL. Ultrabroadband Terahertz Near-Field Nanospectroscopy with a HgCdTe Detector. ACS PHOTONICS 2023; 10:4329-4339. [PMID: 38145170 PMCID: PMC10739990 DOI: 10.1021/acsphotonics.3c01148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 10/27/2023] [Accepted: 11/01/2023] [Indexed: 12/26/2023]
Abstract
While near-field infrared nanospectroscopy provides a powerful tool for nanoscale material characterization, broadband nanospectroscopy of elementary material excitations in the single-digit terahertz (THz) range remains relatively unexplored. Here, we study liquid-Helium-cooled photoconductive Hg1-XCdXTe (MCT) for use as a fast detector in near-field nanospectroscopy. Compared to the common T = 77 K operation, liquid-Helium cooling reduces the MCT detection threshold to ∼22 meV, improves the noise performance, and yields a response bandwidth exceeding 10 MHz. These improved detector properties have a profound impact on the near-field technique, enabling unprecedented broadband nanospectroscopy across a range of 5 to >50 THz (175 to >1750 cm-1, or <6 to 57 μm), i.e., covering what is commonly known as the "THz gap". Our approach has been implemented as a user program at the National Synchrotron Light Source II, Upton, USA, where we showcase ultrabroadband synchrotron nanospectroscopy of phonons in ZnSe (∼7.8 THz) and BaF2 (∼6.7 THz), as well as hyperbolic phonon polaritons in GeS (6-8 THz).
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Affiliation(s)
- Lukas Wehmeier
- National
Synchrotron Light Source II, Brookhaven
National Laboratory; Upton, New York 11973, United States
- Department
of Physics and Astronomy, Stony Brook University; Stony Brook, New York 11794, United States
| | - Mengkun Liu
- National
Synchrotron Light Source II, Brookhaven
National Laboratory; Upton, New York 11973, United States
- Department
of Physics and Astronomy, Stony Brook University; Stony Brook, New York 11794, United States
| | - Suji Park
- Center
for Functional Nanomaterials, Brookhaven
National Laboratory, Upton, New York 11973, United States
| | - Houk Jang
- Center
for Functional Nanomaterials, Brookhaven
National Laboratory, Upton, New York 11973, United States
| | - D. N. Basov
- Department
of Physics, Columbia University; New York, New York 10027, United States
| | - Christopher C. Homes
- National
Synchrotron Light Source II, Brookhaven
National Laboratory; Upton, New York 11973, United States
| | - G. Lawrence Carr
- National
Synchrotron Light Source II, Brookhaven
National Laboratory; Upton, New York 11973, United States
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6
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Obst M, Nörenberg T, Álvarez-Pérez G, de Oliveira TVAG, Taboada-Gutiérrez J, Feres FH, Kaps FG, Hatem O, Luferau A, Nikitin AY, Klopf JM, Alonso-González P, Kehr SC, Eng LM. Terahertz Twistoptics-Engineering Canalized Phonon Polaritons. ACS NANO 2023; 17:19313-19322. [PMID: 37738305 DOI: 10.1021/acsnano.3c06477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/24/2023]
Abstract
The terahertz (THz) frequency range is key to studying collective excitations in many crystals and organic molecules. However, due to the large wavelength of THz radiation, the local probing of these excitations in smaller crystalline structures or few-molecule arrangements requires sophisticated methods to confine THz light down to the nanometer length scale, as well as to manipulate such a confined radiation. For this purpose, in recent years, taking advantage of hyperbolic phonon polaritons (HPhPs) in highly anisotropic van der Waals (vdW) materials has emerged as a promising approach, offering a multitude of manipulation options, such as control over the wavefront shape and propagation direction. Here, we demonstrate the THz application of twist-angle-induced HPhP manipulation, designing the propagation of confined THz radiation between 8.39 and 8.98 THz in the vdW material α-molybdenum trioxide (α-MoO3), hence extending twistoptics to this intriguing frequency range. Our images, recorded by near-field optical microscopy, show the frequency- and twist-angle-dependent changes between hyperbolic and elliptic polariton propagation, revealing a polaritonic transition at THz frequencies. As a result, we are able to allocate canalization (highly collimated propagation) of confined THz radiation by carefully adjusting these two parameters, i.e. frequency and twist angle. Specifically, we report polariton canalization in α-MoO3 at 8.67 THz for a twist angle of 50°. Our results demonstrate the precise control and manipulation of confined collective excitations at THz frequencies, particularly offering possibilities for nanophotonic applications.
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Affiliation(s)
- Maximilian Obst
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
| | - Tobias Nörenberg
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
| | - Gonzalo Álvarez-Pérez
- Department of Physics, University of Oviedo, Oviedo 33006, Spain
- Center of Research on Nanomaterials and Nanotechnology CINN (CSIC-Universidad de Oviedo), El Entrego 33940, Spain
| | - Thales V A G de Oliveira
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Javier Taboada-Gutiérrez
- Department of Quantum Matter Physics, Université de Genève, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Flávio H Feres
- Gleb Wataghin Physics Institute, University of Campinas (Unicamp), Campinas, Sao Paulo 13083-859, Brazil
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Sao Paulo 13083-100, Brazil
| | - Felix G Kaps
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
| | - Osama Hatem
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
- Department of Engineering Physics and Mathematics, Faculty of Engineering, Tanta University, Tanta 31511, Egypt
| | - Andrei Luferau
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Alexey Y Nikitin
- Donostia International Physics Center (DIPC), Donostia/San Sebastián 20018, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao 48013, Spain
| | - J Michael Klopf
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Pablo Alonso-González
- Department of Physics, University of Oviedo, Oviedo 33006, Spain
- Center of Research on Nanomaterials and Nanotechnology CINN (CSIC-Universidad de Oviedo), El Entrego 33940, Spain
| | - Susanne C Kehr
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
| | - Lukas M Eng
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
- Collaborative Research Center 1415, Technische Universität Dresden, Dresden 01069, Germany
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7
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Feres FH, Barcelos ID, Cadore AR, Wehmeier L, Nörenberg T, Mayer RA, Freitas RO, Eng LM, Kehr SC, Maia FCB. Graphene Nano-Optics in the Terahertz Gap. NANO LETTERS 2023; 23:3913-3920. [PMID: 37126430 DOI: 10.1021/acs.nanolett.3c00578] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Graphene nano-optics at terahertz (THz) frequencies (ν) is theoretically anticipated to feature extraordinary effects. However, interrogating such phenomena is nontrivial, since the atomically thin graphene dimensionally mismatches the THz radiation wavelength reaching hundreds of micrometers. Greater challenges happen in the THz gap (0.1-10 THz) wherein light sources are scarce. To surpass these barriers, we use a nanoscope illuminated by a highly brilliant and tunable free-electron laser to image the graphene nano-optical response from 1.5 to 6.0 THz. For ν < 2 THz, we observe a metal-like behavior of graphene, which screens optical fields akin to noble metals, since this excitation range approaches its charge relaxation frequency. At 3.8 THz, plasmonic resonances cause a field-enhancement effect (FEE) that improves the graphene imaging power. Moreover, we show that the metallic behavior and the FEE are tunable upon electrical doping, thus providing further control of these graphene nano-optical properties in the THz gap.
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Affiliation(s)
- Flávio H Feres
- "Gleb Wataghin" Institute of Physics, State University of Campinas (UNICAMP), Campinas, Sao Paulo 13083-859, Brazil
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Sao Paulo 13083-970, Brazil
- Institute of Applied Physics, Technische Universität Dresden, 01062 Dresden, Germany
| | - Ingrid D Barcelos
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Sao Paulo 13083-970, Brazil
| | - Alisson R Cadore
- Brazilian Nanotechnology National Laboratory LNNano, Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Sao Paulo 13083-970, Brazil
| | - Lukas Wehmeier
- Institute of Applied Physics, Technische Universität Dresden, 01062 Dresden, Germany
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States of America
| | - Tobias Nörenberg
- Institute of Applied Physics, Technische Universität Dresden, 01062 Dresden, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Technische Universität Dresden, 01062 Dresden, Germany
| | - Rafael A Mayer
- "Gleb Wataghin" Institute of Physics, State University of Campinas (UNICAMP), Campinas, Sao Paulo 13083-859, Brazil
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Sao Paulo 13083-970, Brazil
| | - Raul O Freitas
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Sao Paulo 13083-970, Brazil
| | - Lukas M Eng
- Institute of Applied Physics, Technische Universität Dresden, 01062 Dresden, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Technische Universität Dresden, 01062 Dresden, Germany
| | - Susanne C Kehr
- Institute of Applied Physics, Technische Universität Dresden, 01062 Dresden, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Technische Universität Dresden, 01062 Dresden, Germany
| | - Francisco C B Maia
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Sao Paulo 13083-970, Brazil
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