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Michael MH, Haque SRU, Windgaetter L, Latini S, Zhang Y, Rubio A, Averitt RD, Demler E. Photonic time-crystalline behaviour mediated by phonon squeezing in Ta 2NiSe 5. Nat Commun 2024; 15:3638. [PMID: 38684735 PMCID: PMC11059354 DOI: 10.1038/s41467-024-47855-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 04/11/2024] [Indexed: 05/02/2024] Open
Abstract
Photonic time crystals refer to materials whose dielectric properties are periodic in time, analogous to a photonic crystal whose dielectric properties is periodic in space. Here, we theoretically investigate photonic time-crystalline behaviour initiated by optical excitation above the electronic gap of the excitonic insulator candidate Ta2NiSe5. We show that after electron photoexcitation, electron-phonon coupling leads to an unconventional squeezed phonon state, characterised by periodic oscillations of phonon fluctuations. Squeezing oscillations lead to photonic time crystalline behaviour. The key signature of the photonic time crystalline behaviour is terahertz (THz) amplification of reflectivity in a narrow frequency band. The theory is supported by experimental results on Ta2NiSe5 where photoexcitation with short pulses leads to enhanced THz reflectivity with the predicted features. We explain the key mechanism leading to THz amplification in terms of a simplified electron-phonon Hamiltonian motivated by ab-initio DFT calculations. Our theory suggests that the pumped Ta2NiSe5 is a gain medium, demonstrating that squeezed phonon noise may be used to create THz amplifiers in THz communication applications.
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Affiliation(s)
- Marios H Michael
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA.
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chausse 149, 22761, Hamburg, Germany.
| | - Sheikh Rubaiat Ul Haque
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA.
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
| | - Lukas Windgaetter
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chausse 149, 22761, Hamburg, Germany
| | - Simone Latini
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chausse 149, 22761, Hamburg, Germany
| | - Yuan Zhang
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chausse 149, 22761, Hamburg, Germany
- Center for Computational Quantum Physics, The Flatiron Institute, 162 Fifth Avenue, New York, 10010, NY, USA
| | - Richard D Averitt
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA
| | - Eugene Demler
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
- Institute for Theoretical Physics, ETH Zürich, 8093, Zürich, Switzerland
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2
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Haque SRU, Michael MH, Zhu J, Zhang Y, Windgätter L, Latini S, Wakefield JP, Zhang GF, Zhang J, Rubio A, Checkelsky JG, Demler E, Averitt RD. Terahertz parametric amplification as a reporter of exciton condensate dynamics. Nat Mater 2024:10.1038/s41563-023-01755-2. [PMID: 38172546 DOI: 10.1038/s41563-023-01755-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 11/06/2023] [Indexed: 01/05/2024]
Abstract
Condensates are a hallmark of emergence in quantum materials such as superconductors and charge density waves. Excitonic insulators are an intriguing addition to this library, exhibiting spontaneous condensation of electron-hole pairs. However, condensate observables can be obscured through parasitic coupling to the lattice. Here we employ nonlinear terahertz spectroscopy to disentangle such obscurants through measurement of the quantum dynamics. We target Ta2NiSe5, a putative room-temperature excitonic insulator in which electron-lattice coupling dominates the structural transition (Tc = 326 K), hindering identification of excitonic correlations. A pronounced increase in the terahertz reflectivity manifests following photoexcitation and exhibits a Bose-Einstein condensation-like temperature dependence well below the Tc, suggesting an approach to monitor the exciton condensate dynamics. Nonetheless, dynamic condensate-phonon coupling remains as evidenced by peaks in the enhanced reflectivity spectrum at select infrared-active phonon frequencies, indicating that parametric reflectivity enhancement arises from phonon squeezing. Our results highlight that coherent dynamics can drive parametric stimulated emission.
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Affiliation(s)
- Sheikh Rubaiat Ul Haque
- Department of Physics, University of California San Diego, La Jolla, CA, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | | | - Junbo Zhu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Yuan Zhang
- Department of Physics, University of California San Diego, La Jolla, CA, USA
| | - Lukas Windgätter
- Max Planck Institute for the Structure and Dynamics of Matter (MPSD), Hamburg, Germany
| | - Simone Latini
- Max Planck Institute for the Structure and Dynamics of Matter (MPSD), Hamburg, Germany
| | - Joshua P Wakefield
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Gu-Feng Zhang
- Department of Physics, University of California San Diego, La Jolla, CA, USA
| | - Jingdi Zhang
- Department of Physics, University of California San Diego, La Jolla, CA, USA
- Department of Physics, The Hong Kong University of Science and Technology, Hongkong, China
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter (MPSD), Hamburg, Germany
- Center for Computational Quantum Physics, The Flatiron Institute, New York, NY, USA
| | - Joseph G Checkelsky
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Eugene Demler
- Department of Physics, Harvard University, Cambridge, MA, USA
- Institute for Theoretical Physics, ETH Zürich, Zürich, Switzerland
| | - Richard D Averitt
- Department of Physics, University of California San Diego, La Jolla, CA, USA.
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3
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Averitt RD. Optical control of spin-galvanic currents. Nat Mater 2023; 22:935-936. [PMID: 37524817 DOI: 10.1038/s41563-023-01613-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Affiliation(s)
- Richard D Averitt
- Department of Physics, University of California San Diego, La Jolla, CA, USA.
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4
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Potts AM, Nayak AK, Nagel M, Kaj K, Stamenic B, John DD, Averitt RD, Young AF. On-Chip Time-Domain Terahertz Spectroscopy of Superconducting Films below the Diffraction Limit. Nano Lett 2023; 23:3835-3841. [PMID: 37126575 DOI: 10.1021/acs.nanolett.3c00412] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Free-space time domain THz spectroscopy accesses electrodynamic responses in a frequency regime ideally matched to interacting condensed matter systems. However, THz spectroscopy is challenging when samples are physically smaller than the diffraction limit of ∼0.5 mm, as is typical, for example, in van der Waals materials and heterostructures. Here, we present an on-chip, time-domain THz spectrometer based on semiconducting photoconductive switches with a bandwidth of 200 to 750 GHz. We measure the optical conductivity of a 7.5-μm wide NbN film across the superconducting transition, demonstrating spectroscopic signatures of the superconducting gap in a sample smaller than 2% of the Rayleigh diffraction limit. Our spectrometer features an interchangeable sample architecture, making it ideal for probing superconductivity, magnetism, and charge order in strongly correlated van der Waals materials.
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Affiliation(s)
- Alex M Potts
- Department of Physics, University of California at Santa Barbara, Santa Barbara California 93106, United States
| | - Abhay K Nayak
- Department of Physics, University of California at Santa Barbara, Santa Barbara California 93106, United States
| | | | - Kelson Kaj
- Department of Physics, University of California at San Diego, La Jolla, California 92093, United States
| | - Biljana Stamenic
- Nanofabrication Facility, Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, United States
| | - Demis D John
- Nanofabrication Facility, Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, United States
| | - Richard D Averitt
- Department of Physics, University of California at San Diego, La Jolla, California 92093, United States
| | - Andrea F Young
- Department of Physics, University of California at Santa Barbara, Santa Barbara California 93106, United States
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5
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Padmanabhan H, Stoica VA, Kim PK, Poore M, Yang T, Shen X, Reid AH, Lin MF, Park S, Yang J, Wang HH, Koocher NZ, Puggioni D, Georgescu AB, Min L, Lee SH, Mao Z, Rondinelli JM, Lindenberg AM, Chen LQ, Wang X, Averitt RD, Freeland JW, Gopalan V. Large Exchange Coupling Between Localized Spins and Topological Bands in MnBi 2 Te 4. Adv Mater 2022; 34:e2202841. [PMID: 36189841 DOI: 10.1002/adma.202202841] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 09/21/2022] [Indexed: 06/16/2023]
Abstract
Magnetism in topological materials creates phases exhibiting quantized transport phenomena with potential technological applications. The emergence of such phases relies on strong interaction between localized spins and the topological bands, and the consequent formation of an exchange gap. However, this remains experimentally unquantified in intrinsic magnetic topological materials. Here, this interaction is quantified in MnBi2 Te4 , a topological insulator with intrinsic antiferromagnetism. This is achieved by optically exciting Bi-Te p states comprising the bulk topological bands and interrogating the consequent Mn 3d spin dynamics, using a multimodal ultrafast approach. Ultrafast electron scattering and magneto-optic measurements show that the p states demagnetize via electron-phonon scattering at picosecond timescales. Despite being energetically decoupled from the optical excitation, the Mn 3d spins, probed by resonant X-ray scattering, are observed to disorder concurrently with the p spins. Together with atomistic simulations, this reveals that the exchange coupling between localized spins and the topological bands is at least 100 times larger than the superexchange interaction, implying an optimal exchange gap of at least 25 meV in the surface states. By quantifying this exchange coupling, this study validates the materials-by-design strategy of utilizing localized magnetic order to manipulate topological phases, spanning static to ultrafast timescales.
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Affiliation(s)
- Hari Padmanabhan
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Vladimir A Stoica
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Peter K Kim
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA
| | - Maxwell Poore
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA
| | - Tiannan Yang
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Xiaozhe Shen
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Alexander H Reid
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Ming-Fu Lin
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Suji Park
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Jie Yang
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Huaiyu Hugo Wang
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Nathan Z Koocher
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Danilo Puggioni
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Alexandru B Georgescu
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Lujin Min
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Seng Huat Lee
- 2D Crystal Consortium, Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Physics, Penn State University, University Park, PA, 16802, USA
| | - Zhiqiang Mao
- 2D Crystal Consortium, Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Physics, Penn State University, University Park, PA, 16802, USA
| | - James M Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Aaron M Lindenberg
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Materials Science and Engineering, Stanford University, Menlo Park, CA, 94305, USA
| | - Long-Qing Chen
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Xijie Wang
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Richard D Averitt
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA
| | - John W Freeland
- X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Venkatraman Gopalan
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
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6
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Sternbach AJ, Ruta FL, Shi Y, Slusar T, Schalch J, Duan G, McLeod AS, Zhang X, Liu M, Millis AJ, Kim HT, Chen LQ, Averitt RD, Basov DN. Nanotextured Dynamics of a Light-Induced Phase Transition in VO 2. Nano Lett 2021; 21:9052-9060. [PMID: 34724612 DOI: 10.1021/acs.nanolett.1c02638] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We investigate transient nanotextured heterogeneity in vanadium dioxide (VO2) thin films during a light-induced insulator-to-metal transition (IMT). Time-resolved scanning near-field optical microscopy (Tr-SNOM) is used to study VO2 across a wide parameter space of infrared frequencies, picosecond time scales, and elevated steady-state temperatures with nanoscale spatial resolution. Room temperature, steady-state, phonon enhanced nano-optical contrast reveals preexisting "hidden" disorder. The observed contrast is associated with inequivalent twin domain structures. Upon thermal or optical initiation of the IMT, coexisting metallic and insulating regions are observed. Correlations between the transient and steady-state nano-optical textures reveal that heterogeneous nucleation is partially anchored to twin domain interfaces and grain boundaries. Ultrafast nanoscopic dynamics enable quantification of the growth rate and bound the nucleation rate. Finally, we deterministically anchor photoinduced nucleation to predefined nanoscopic regions by locally enhancing the electric field of pump radiation using nanoantennas and monitor the on-demand emergent metallicity in space and time.
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Affiliation(s)
- Aaron J Sternbach
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Francesco L Ruta
- Department of Physics, Columbia University, New York, New York 10027, United States
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
| | - Yin Shi
- Department of Materials Science and Engineering, The Pennsylvania State University, State College, Pennsylvania 16801,United States
| | - Tetiana Slusar
- Electronics and Telecommunications Research Institute, Daejeon 34129, Republic of Korea
| | - Jacob Schalch
- Department of Physics, University of California San Diego, San Diego, California 92093, United States
| | - Guangwu Duan
- Department of Physics, Boston University, Boston, Massachusetts 02215, United States
| | - Alexander S McLeod
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Xin Zhang
- Department of Physics, Boston University, Boston, Massachusetts 02215, United States
| | - Mengkun Liu
- Department of Physics, Stony Brook University, Stony Brook, New York 11790, United States
| | - Andrew J Millis
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Hyun-Tak Kim
- Electronics and Telecommunications Research Institute, Daejeon 34129, Republic of Korea
| | - Long-Qing Chen
- Department of Materials Science and Engineering, The Pennsylvania State University, State College, Pennsylvania 16801,United States
| | - Richard D Averitt
- Department of Physics, University of California San Diego, San Diego, California 92093, United States
| | - D N Basov
- Department of Physics, Columbia University, New York, New York 10027, United States
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7
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Sternbach AJ, Chae SH, Latini S, Rikhter AA, Shao Y, Li B, Rhodes D, Kim B, Schuck PJ, Xu X, Zhu XY, Averitt RD, Hone J, Fogler MM, Rubio A, Basov DN. Programmable hyperbolic polaritons in van der Waals semiconductors. Science 2021; 371:617-620. [PMID: 33542134 DOI: 10.1126/science.abe9163] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 12/22/2020] [Indexed: 12/17/2022]
Abstract
Collective electronic modes or lattice vibrations usually prohibit propagation of electromagnetic radiation through the bulk of common materials over a frequency range associated with these oscillations. However, this textbook tenet does not necessarily apply to layered crystals. Highly anisotropic materials often display nonintuitive optical properties and can permit propagation of subdiffractional waveguide modes, with hyperbolic dispersion, throughout their bulk. Here, we report on the observation of optically induced electronic hyperbolicity in the layered transition metal dichalcogenide tungsten diselenide (WSe2). We used photoexcitation to inject electron-hole pairs in WSe2 and then visualized, by transient nanoimaging, the hyperbolic rays that traveled along conical trajectories inside of the crystal. We establish here the signatures of programmable hyperbolic electrodynamics and assess the role of quantum transitions of excitons within the Rydberg series in the observed polaritonic response.
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Affiliation(s)
- A J Sternbach
- Department of Physics, Columbia University, New York, NY 10027, USA.
| | - S H Chae
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | - S Latini
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - A A Rikhter
- Department of Physics, University of California-San Diego, La Jolla, CA 92093, USA
| | - Y Shao
- Department of Physics, Columbia University, New York, NY 10027, USA
| | - B Li
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | - D Rhodes
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | - B Kim
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | - P J Schuck
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | - X Xu
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - X-Y Zhu
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - R D Averitt
- Department of Physics, University of California-San Diego, La Jolla, CA 92093, USA
| | - J Hone
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | - M M Fogler
- Department of Physics, University of California-San Diego, La Jolla, CA 92093, USA
| | - A Rubio
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany.,Center for Computational Quantum Physics (CCQ), Flatiron Institute, New York, NY 10010, USA
| | - D N Basov
- Department of Physics, Columbia University, New York, NY 10027, USA
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8
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Berkowitz ME, Kim BSY, Ni G, McLeod AS, Lo CFB, Sun Z, Gu G, Watanabe K, Taniguchi T, Millis AJ, Hone JC, Fogler MM, Averitt RD, Basov DN. Hyperbolic Cooper-Pair Polaritons in Planar Graphene/Cuprate Plasmonic Cavities. Nano Lett 2021; 21:308-316. [PMID: 33320013 DOI: 10.1021/acs.nanolett.0c03684] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Hyperbolic Cooper-pair polaritons (HCP) in cuprate superconductors are of fundamental interest due to their potential for providing insights into the nature of unconventional superconductivity. Here, we critically assess an experimental approach using near-field imaging to probe HCP in Bi2Sr2CaCu2O8+x (Bi-2212) in the presence of graphene surface plasmon polaritons (SPP). Our simulations show that inherently weak HCP features in the near-field can be strongly enhanced when coupled to graphene SPP in layered graphene/hexagonal boron nitride (hBN)/Bi-2212 heterostructures. This enhancement arises from our multilayered structures effectively acting as plasmonic cavities capable of altering collective modes of a layered superconductor by modifying its electromagnetic environment. The degree of enhancement can be selectively controlled by tuning the insulating spacer thickness with atomic precision. Finally, we verify the expected renormalization of room-temperature graphene SPP using near-field infrared imaging. Our modeling, augmented with data, attests to the validity of our approach for probing HCP modes in cuprate superconductors.
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Affiliation(s)
- Michael E Berkowitz
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Brian S Y Kim
- Department of Physics, Columbia University, New York, New York 10027, United States
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Guangxin Ni
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Alexander S McLeod
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Chiu Fan Bowen Lo
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Zhiyuan Sun
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Genda Gu
- Condensed Matter Physics and Material Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute of Material Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute of Material Science, Namiki 1-1, Tsukaba, Ibaraki 305-0044, Japan
| | - Andrew J Millis
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - James C Hone
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Michael M Fogler
- Department of Physics, University of California San Diego, La Jolla, California 92093, United States
| | - Richard D Averitt
- Department of Physics, University of California San Diego, La Jolla, California 92093, United States
| | - D N Basov
- Department of Physics, Columbia University, New York, New York 10027, United States
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9
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Ron A, Chaudhary S, Zhang G, Ning H, Zoghlin E, Wilson SD, Averitt RD, Refael G, Hsieh D. Ultrafast Enhancement of Ferromagnetic Spin Exchange Induced by Ligand-to-Metal Charge Transfer. Phys Rev Lett 2020; 125:197203. [PMID: 33216570 DOI: 10.1103/physrevlett.125.197203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 08/17/2020] [Accepted: 10/02/2020] [Indexed: 06/11/2023]
Abstract
We theoretically predict and experimentally demonstrate a nonthermal pathway to optically enhance superexchange interaction energies in a material based on exciting ligand-to-metal charge-transfer transitions, which introduces lower-order virtual hopping contributions that are absent in the ground state. We demonstrate this effect in the layered ferromagnetic insulator CrSiTe_{3} by exciting Te-to-Cr charge-transfer transitions using ultrashort laser pulses and detecting coherent phonon oscillations that are impulsively generated by superexchange enhancement via magneto-elastic coupling. This mechanism kicks in below the temperature scale where short-range in-plane spin correlations begin to develop and disappears when the excitation energy is tuned away from the charge-transfer resonance, consistent with our predictions.
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Affiliation(s)
- A Ron
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv, 69978, Israel
| | - S Chaudhary
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
| | - G Zhang
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - H Ning
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
| | - E Zoghlin
- Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, USA
| | - S D Wilson
- Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, USA
| | - R D Averitt
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - G Refael
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
| | - D Hsieh
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
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10
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Abreu E, Meyers D, Thorsmølle VK, Zhang J, Liu X, Geng K, Chakhalian J, Averitt RD. Nucleation and Growth Bottleneck in the Conductivity Recovery Dynamics of Nickelate Ultrathin Films. Nano Lett 2020; 20:7422-7428. [PMID: 32902285 DOI: 10.1021/acs.nanolett.0c02828] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We investigate THz conductivity dynamics in NdNiO3 and EuNiO3 ultrathin films (15 unit cells, u.c., ∼5.7 nm thick) following a photoinduced thermal quench into the metallic state and reveal a clear contrast between first- and second-order dynamics. While in EuNiO3 the conductivity recovers exponentially, in NdNiO3 the recovery is nonexponential and slower than a simple thermal model. Crucially, it is consistent with first-order dynamics and well-described by a 2d Avrami model, with supercooling leading to metastable phase coexistence on the nano- to mesoscopic scale. This novel observation is a fundamentally dynamic manifestation of the first-order character of the insulator-to-metal transition, which the nanoscale thickness of our films and their fast cooling rate enable us to detect. The large transients seen in our films are promising for fast electronic (and magnetic) switching applications.
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Affiliation(s)
- E Abreu
- Institute for Quantum Electronics, Department of Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - D Meyers
- Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - V K Thorsmølle
- Department of Physics, Boston University, Boston, Massachusetts 02215, United States
- Department of Physics, UC San Diego, La Jolla, California 92093, United States
| | - J Zhang
- Department of Physics, UC San Diego, La Jolla, California 92093, United States
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - X Liu
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, United States
| | - K Geng
- Department of Physics, Boston University, Boston, Massachusetts 02215, United States
| | - J Chakhalian
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, United States
| | - R D Averitt
- Department of Physics, UC San Diego, La Jolla, California 92093, United States
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11
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Sternbach AJ, Latini S, Chae S, Hübener H, De Giovannini U, Shao Y, Xiong L, Sun Z, Shi N, Kissin P, Ni GX, Rhodes D, Kim B, Yu N, Millis AJ, Fogler MM, Schuck PJ, Lipson M, Zhu XY, Hone J, Averitt RD, Rubio A, Basov DN. Femtosecond exciton dynamics in WSe 2 optical waveguides. Nat Commun 2020; 11:3567. [PMID: 32678086 PMCID: PMC7367278 DOI: 10.1038/s41467-020-17335-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/17/2020] [Indexed: 11/29/2022] Open
Abstract
Van-der Waals (vdW) atomically layered crystals can act as optical waveguides over a broad range of the electromagnetic spectrum ranging from Terahertz to visible. Unlike common Si-based waveguides, vdW semiconductors host strong excitonic resonances that may be controlled using non-thermal stimuli including electrostatic gating and photoexcitation. Here, we utilize waveguide modes to examine photo-induced changes of excitons in the prototypical vdW semiconductor, WSe2, prompted by femtosecond light pulses. Using time-resolved scanning near-field optical microscopy we visualize the electric field profiles of waveguide modes in real space and time and extract the temporal evolution of the optical constants following femtosecond photoexcitation. By monitoring the phase velocity of the waveguide modes, we detect incoherent A-exciton bleaching along with a coherent optical Stark shift in WSe2. The authors use time-resolved scanning near-field optical microscopy to probe the ultrafast excitonic processes and their impact on waveguide operation in transition metal dichalcogenide crystals. They observe significant modulation of the complex index by monitoring waveguide modes on the fs time scale, and identify both coherent and incoherent manipulations of WSe2 excitonic resonances.
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Affiliation(s)
- Aaron J Sternbach
- Department of Physics, Columbia University, New York, NY, 10027, USA.
| | - Simone Latini
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761, Hamburg, Germany
| | - Sanghoon Chae
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Hannes Hübener
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761, Hamburg, Germany
| | - Umberto De Giovannini
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761, Hamburg, Germany
| | - Yinming Shao
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Lin Xiong
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Zhiyuan Sun
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Norman Shi
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Peter Kissin
- Department of Physics, University of California, San Diego, La Jolla, 92093, CA, USA
| | - Guang-Xin Ni
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Daniel Rhodes
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Brian Kim
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Nanfang Yu
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Andrew J Millis
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Michael M Fogler
- Department of Physics, University of California, San Diego, La Jolla, 92093, CA, USA
| | - Peter J Schuck
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Michal Lipson
- Department of Electrical Engineering, Columbia University, New York, NY, 10027, USA
| | - X-Y Zhu
- Department of Chemistry, Columbia University, New York, NY, 10027, USA
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Richard D Averitt
- Department of Physics, University of California, San Diego, La Jolla, 92093, CA, USA
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761, Hamburg, Germany.,Center for Computational Quantum Physics (CCQ), Flatiron Institute, 162 Fifth Avenue, New York, NY, 10010, USA
| | - D N Basov
- Department of Physics, Columbia University, New York, NY, 10027, USA
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12
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McLeod AS, Zhang J, Gu MQ, Jin F, Zhang G, Post KW, Zhao XG, Millis AJ, Wu WB, Rondinelli JM, Averitt RD, Basov DN. Multi-messenger nanoprobes of hidden magnetism in a strained manganite. Nat Mater 2020; 19:397-404. [PMID: 31844275 DOI: 10.1038/s41563-019-0533-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 10/09/2019] [Indexed: 06/10/2023]
Abstract
The ground-state properties of correlated electron systems can be extraordinarily sensitive to external stimuli, offering abundant platforms for functional materials. Using the multi-messenger combination of atomic force microscopy, cryogenic scanning near-field optical microscopy, magnetic force microscopy and ultrafast laser excitation, we demonstrate both 'writing' and 'erasing' of a metastable ferromagnetic metal phase in strained films of La2/3Ca1/3MnO3 (LCMO) with nanometre-resolved finesse. By tracking both optical conductivity and magnetism at the nanoscale, we reveal how strain-coupling underlies the dynamic growth, spontaneous nanotexture and first-order melting transition of this hidden photoinduced metal. Our first-principles calculations reveal that epitaxially engineered Jahn-Teller distortion can stabilize nearly degenerate antiferromagnetic insulator and ferromagnetic metal phases. We propose a Ginzburg-Landau description to rationalize the co-active interplay of strain, lattice distortions and magnetism nano-resolved here in strained LCMO, thus guiding future functional engineering of epitaxial oxides into the regime of phase-programmable materials.
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Affiliation(s)
- A S McLeod
- Department of Physics, Columbia University, New York, NY, USA.
| | - Jingdi Zhang
- Department of Physics, University of California San Diego, La Jolla, CA, USA.
- Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
| | - M Q Gu
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - F Jin
- Hefei National Laboratory for Physical Sciences at Microscale and High Magnetic Field Laboratory of CAS, University of Science and Technology of China, Hefei, China
| | - G Zhang
- Department of Physics, University of California San Diego, La Jolla, CA, USA
| | - K W Post
- Department of Physics, University of California San Diego, La Jolla, CA, USA
| | - X G Zhao
- Department of Mechanical Engineering, Boston University, Boston, MA, USA
| | - A J Millis
- Department of Physics, Columbia University, New York, NY, USA
| | - W B Wu
- Hefei National Laboratory for Physical Sciences at Microscale and High Magnetic Field Laboratory of CAS, University of Science and Technology of China, Hefei, China
- Institute of Physical Science and Information Technology, Anhui University, Hefei, China
| | - J M Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - R D Averitt
- Department of Physics, University of California San Diego, La Jolla, CA, USA
| | - D N Basov
- Department of Physics, Columbia University, New York, NY, USA
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13
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Teitelbaum SW, Ofori-Okai BK, Cheng YH, Zhang J, Jin F, Wu W, Averitt RD, Nelson KA. Dynamics of a Persistent Insulator-to-Metal Transition in Strained Manganite Films. Phys Rev Lett 2019; 123:267201. [PMID: 31951459 DOI: 10.1103/physrevlett.123.267201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Indexed: 06/10/2023]
Abstract
Transition metal oxides possess complex free-energy surfaces with competing degrees of freedom. Photoexcitation allows shaping of such rich energy landscapes. In epitaxially strained La_{0.67}Ca_{0.33}MnO_{3}, optical excitation with a sub-100-fs pulse above 2 mJ/cm^{2} leads to a persistent metallic phase below 100 K. Using single-shot optical and terahertz spectroscopy, we show that this phase transition is a multistep process. We conclude that the phase transition is driven by partial charge-order melting, followed by growth of the persistent metallic phase on longer timescales. A time-dependent Ginzburg-Landau model can describe the fast dynamics of the reflectivity, followed by longer timescale in-growth of the metallic phase.
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Affiliation(s)
- Samuel W Teitelbaum
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - B K Ofori-Okai
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Yu-Hsiang Cheng
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jingdi Zhang
- Department of Physics, University of California San Diego, La Jolla, California 92093, USA
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Feng Jin
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
- Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Wenbin Wu
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
- Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Richard D Averitt
- Department of Physics, University of California San Diego, La Jolla, California 92093, USA
| | - Keith A Nelson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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14
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Fan K, Zhang J, Liu X, Zhang GF, Averitt RD, Padilla WJ. Phototunable Dielectric Huygens' Metasurfaces. Adv Mater 2018; 30:e1800278. [PMID: 29635850 DOI: 10.1002/adma.201800278] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 03/03/2018] [Indexed: 06/08/2023]
Abstract
Conventional dielectric metasurfaces achieve their properties through geometrical tuning and consequently are static. Although some unique properties are demonstrated, the usefulness for realistic applications is thus inherently limited. Here, control of the resonant eigenmodes supported by Huygens' metasurface (HMS) absorbers through optical excitation is proposed and demonstrated. An intensity transmission modulation depth of 99.93% is demonstrated at 1.03 THz, with an associated phase change of greater than π/2 rad. Coupled mode theory and S-parameter simulations are used to elucidate the mechanism underlying the dynamics of the metasurface and it is found that the tuning is primarily governed by modification of the magnetic dipole-like odd eigenmode, which both lifts the degeneracy, and eliminates critical coupling. The dynamic HMS demonstrates wide tunability and versatility which is not limited to the spectral range demonstrated, offering a new path for reconfigurable metasurface applications.
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Affiliation(s)
- Kebin Fan
- Department of Electrical and Computer Engineering, Duke University, Box 90291, Durham, NC, 27708, USA
| | - Jingdi Zhang
- Department of Physics, The University of California at San Diego, La Jolla, CA, 92093, USA
| | - Xinyu Liu
- Department of Electrical and Computer Engineering, Duke University, Box 90291, Durham, NC, 27708, USA
| | - Gu-Feng Zhang
- Department of Physics, The University of California at San Diego, La Jolla, CA, 92093, USA
| | - Richard D Averitt
- Department of Physics, The University of California at San Diego, La Jolla, CA, 92093, USA
| | - Willie J Padilla
- Department of Electrical and Computer Engineering, Duke University, Box 90291, Durham, NC, 27708, USA
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15
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Duan G, Schalch J, Zhao X, Zhang J, Averitt RD, Zhang X. Analysis of the thickness dependence of metamaterial absorbers at terahertz frequencies. Opt Express 2018; 26:2242-2251. [PMID: 29401764 DOI: 10.1364/oe.26.002242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 01/17/2018] [Indexed: 06/07/2023]
Abstract
Metamaterial absorbers typically consist of a metamaterial layer, a dielectric spacer layer, and a metallic ground plane. We have investigated the dependence of the metamaterial absorption maxima on the spacer layer thickness and the reflection coefficient of the metamaterial layer obtained in the absence of the ground plane layer. Specifically, we employ interference theory to obtain an analytical expression for the spacer thickness needed to maximize the absorption at a given frequency. The efficacy of this simple expression is experimentally verified at terahertz frequencies through detailed measurements of the absorption spectra of a series of metamaterials structures with different spacer thicknesses. Using an array of split-ring resonators (SRRs) as the metamaterial layer and SU8 as the spacer material we observe that the absorption peaks redshift as the spacer thickness is increased, in excellent agreement with our analysis. Our findings can be applied to guide metamaterial absorber designs and understand the absorption peak frequency shift of sensors based on metamaterial absorbers.
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16
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Basov DN, Averitt RD, Hsieh D. Towards properties on demand in quantum materials. Nat Mater 2017; 16:1077-1088. [PMID: 29066824 DOI: 10.1038/nmat5017] [Citation(s) in RCA: 194] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 09/22/2017] [Indexed: 05/21/2023]
Abstract
The past decade has witnessed an explosion in the field of quantum materials, headlined by the predictions and discoveries of novel Landau-symmetry-broken phases in correlated electron systems, topological phases in systems with strong spin-orbit coupling, and ultra-manipulable materials platforms based on two-dimensional van der Waals crystals. Discovering pathways to experimentally realize quantum phases of matter and exert control over their properties is a central goal of modern condensed-matter physics, which holds promise for a new generation of electronic/photonic devices with currently inaccessible and likely unimaginable functionalities. In this Review, we describe emerging strategies for selectively perturbing microscopic interaction parameters, which can be used to transform materials into a desired quantum state. Particular emphasis will be placed on recent successes to tailor electronic interaction parameters through the application of intense fields, impulsive electromagnetic stimulation, and nanostructuring or interface engineering. Together these approaches outline a potential roadmap to an era of quantum phenomena on demand.
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Affiliation(s)
- D N Basov
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - R D Averitt
- Department of Physics, University of California San Diego, La Jolla, California 92093, USA
| | - D Hsieh
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
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17
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Zhang J, Tan X, Liu M, Teitelbaum SW, Post KW, Jin F, Nelson KA, Basov DN, Wu W, Averitt RD. Cooperative photoinduced metastable phase control in strained manganite films. Nat Mater 2016; 15:956-960. [PMID: 27400387 DOI: 10.1038/nmat4695] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 06/10/2016] [Indexed: 06/06/2023]
Abstract
A major challenge in condensed-matter physics is active control of quantum phases. Dynamic control with pulsed electromagnetic fields can overcome energetic barriers, enabling access to transient or metastable states that are not thermally accessible. Here we demonstrate strain-engineered tuning of La2/3Ca1/3MnO3 into an emergent charge-ordered insulating phase with extreme photo-susceptibility, where even a single optical pulse can initiate a transition to a long-lived metastable hidden metallic phase. Comprehensive single-shot pulsed excitation measurements demonstrate that the transition is cooperative and ultrafast, requiring a critical absorbed photon density to activate local charge excitations that mediate magnetic-lattice coupling that, in turn, stabilize the metallic phase. These results reveal that strain engineering can tune emergent functionality towards proximal macroscopic states to enable dynamic ultrafast optical phase switching and control.
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Affiliation(s)
- Jingdi Zhang
- Department of Physics, University of California at San Diego, La Jolla, California 92093, USA
- Department of Physics, Boston University, Boston, Massachusetts 02215, USA
| | - Xuelian Tan
- Hefei National Laboratory for Physical Sciences at Microscale, and High Magnetic Field Laboratory of Chinese Academy of Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Mengkun Liu
- Department of Physics, University of California at San Diego, La Jolla, California 92093, USA
- Department of Physics, Stony Brook University, Stony Brook, New York 11790, USA
| | - S W Teitelbaum
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - K W Post
- Department of Physics, University of California at San Diego, La Jolla, California 92093, USA
| | - Feng Jin
- Hefei National Laboratory for Physical Sciences at Microscale, and High Magnetic Field Laboratory of Chinese Academy of Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - K A Nelson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - D N Basov
- Department of Physics, University of California at San Diego, La Jolla, California 92093, USA
| | - Wenbin Wu
- Hefei National Laboratory for Physical Sciences at Microscale, and High Magnetic Field Laboratory of Chinese Academy of Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
- Collaborative Innovation Center of Advanced Microstructure, Nanjing 210093, China
| | - R D Averitt
- Department of Physics, University of California at San Diego, La Jolla, California 92093, USA
- Department of Physics, Boston University, Boston, Massachusetts 02215, USA
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18
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Seren HR, Zhang J, Keiser GR, Maddox SJ, Zhao X, Fan K, Bank SR, Zhang X, Averitt RD. Nonlinear terahertz devices utilizing semiconducting plasmonic metamaterials. Light Sci Appl 2016; 5:e16078. [PMID: 30167165 PMCID: PMC6059934 DOI: 10.1038/lsa.2016.78] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 01/21/2016] [Accepted: 01/25/2016] [Indexed: 06/01/2023]
Abstract
The development of responsive metamaterials has enabled the realization of compact tunable photonic devices capable of manipulating the amplitude, polarization, wave vector and frequency of light. Integration of semiconductors into the active regions of metallic resonators is a proven approach for creating nonlinear metamaterials through optoelectronic control of the semiconductor carrier density. Metal-free subwavelength resonant semiconductor structures offer an alternative approach to create dynamic metamaterials. We present InAs plasmonic disk arrays as a viable resonant metamaterial at terahertz frequencies. Importantly, InAs plasmonic disks exhibit a strong nonlinear response arising from electric field-induced intervalley scattering, resulting in a reduced carrier mobility thereby damping the plasmonic response. We demonstrate nonlinear perfect absorbers configured as either optical limiters or saturable absorbers, including flexible nonlinear absorbers achieved by transferring the disks to polyimide films. Nonlinear plasmonic metamaterials show potential for use in ultrafast terahertz (THz) optics and for passive protection of sensitive electromagnetic devices.
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Affiliation(s)
- Huseyin R Seren
- Laboratory for Microsystems Technology, Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
| | - Jingdi Zhang
- Department of Physics, Boston University, Boston, MA 02215, USA
- Department of Physics, UC San Diego, La Jolla, CA 92093, USA
| | - George R Keiser
- Department of Physics, Boston University, Boston, MA 02215, USA
- School of Engineering, Brown University, Providence, RI 02912, USA
| | - Scott J Maddox
- Microelectronics Research Center, The University of Texas at Austin, Austin, TX 78758, USA
| | - Xiaoguang Zhao
- Laboratory for Microsystems Technology, Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
| | - Kebin Fan
- Laboratory for Microsystems Technology, Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
| | - Seth R Bank
- Microelectronics Research Center, The University of Texas at Austin, Austin, TX 78758, USA
| | - Xin Zhang
- Laboratory for Microsystems Technology, Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
| | - Richard D Averitt
- Department of Physics, Boston University, Boston, MA 02215, USA
- Department of Physics, UC San Diego, La Jolla, CA 92093, USA
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19
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Zhao X, Fan K, Zhang J, Keiser GR, Duan G, Averitt RD, Zhang X. Voltage-tunable dual-layer terahertz metamaterials. Microsyst Nanoeng 2016; 2:16025. [PMID: 31057825 PMCID: PMC6444717 DOI: 10.1038/micronano.2016.25] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 04/11/2016] [Accepted: 04/12/2016] [Indexed: 05/05/2023]
Abstract
This paper presents the design, fabrication, and characterization of a real-time voltage-tunable terahertz metamaterial based on microelectromechanical systems and broadside-coupled split-ring resonators. In our metamaterial, the magnetic and electric interactions between the coupled resonators are modulated by a comb-drive actuator, which provides continuous lateral shifting between the coupled resonators by up to 20 μm. For these strongly coupled split-ring resonators, both a symmetric mode and an anti-symmetric mode are observed. With increasing lateral shift, the electromagnetic interactions between the split-ring resonators weaken, resulting in frequency shifting of the resonant modes. Over the entire lateral shift range, the symmetric mode blueshifts by ~60 GHz, and the anti-symmetric mode redshifts by ~50 GHz. The amplitude of the transmission at 1.03 THz is modulated by 74%; moreover, a 180° phase shift is achieved at 1.08 THz. Our tunable metamaterial device has myriad potential applications, including terahertz spatial light modulation, phase modulation, and chemical sensing. Furthermore, the scheme that we have implemented can be scaled to operate at other frequencies, thereby enabling a wide range of distinct applications.
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Affiliation(s)
- Xiaoguang Zhao
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
| | - Kebin Fan
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
| | - Jingdi Zhang
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Physics, Boston University, Boston, MA 02215, USA
| | - George R Keiser
- Department of Physics, Boston University, Boston, MA 02215, USA
| | - Guangwu Duan
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
| | - Richard D Averitt
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Physics, Boston University, Boston, MA 02215, USA
- ()
| | - Xin Zhang
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
- ()
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20
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Teo SM, Werley CA, Wang C, Fan K, Ofori-Okai BK, Zhang X, Averitt RD, Nelson KA. Visualization of guided and leaky wave behaviors in an indium tin oxide metallic slab waveguide. Opt Express 2015; 23:14876-14896. [PMID: 26072845 DOI: 10.1364/oe.23.014876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We explored the use of the optically transparent semiconductor indium tin oxide (ITO) as an alternative to optically opaque metals for the fabrication of photonic structures in terahertz (THz) near-field studies. Using the polaritonics platform, we confirmed the ability to clearly image both bound and leaky electric fields underneath an ITO layer. We observed good agreement between measured waveguide dispersion and analytical theory of an asymmetric metal-clad planar waveguide with TE and TM polarizations. Further characterization of the ITO revealed that even moderately conductive samples provided sufficiently high quality factors for studying guided and leaky wave behaviors in individual transparent THz resonant structures such as antennas or split ring resonators. However, without higher conductive ITO, the limited reflection efficiency and high radiation damping measured here both diminish the applicability of ITO for high-reflecting, arrayed, or long path-length elements.
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21
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Wagner M, McLeod AS, Maddox SJ, Fei Z, Liu M, Averitt RD, Fogler MM, Bank SR, Keilmann F, Basov DN. Ultrafast dynamics of surface plasmons in InAs by time-resolved infrared nanospectroscopy. Nano Lett 2014; 14:4529-34. [PMID: 25046340 DOI: 10.1021/nl501558t] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We report on time-resolved mid-infrared (mid-IR) near-field spectroscopy of the narrow bandgap semiconductor InAs. The dominant effect we observed pertains to the dynamics of photoexcited carriers and associated surface plasmons. A novel combination of pump-probe techniques and near-field nanospectroscopy accesses high momentum plasmons and demonstrates efficient, subpicosecond photomodulation of the surface plasmon dispersion with subsequent tens of picoseconds decay under ambient conditions. The photoinduced change of the probe intensity due to plasmons in InAs is found to exceed that of other mid-IR or near-IR media by 1-2 orders of magnitude. Remarkably, the required control pulse fluence is as low as 60 μJ/cm(2), much smaller than fluences of ∼ 1-10 mJ/cm(2) previously utilized in ultrafast control of near-IR plasmonics. These low excitation densities are easily attained with a standard 1.56 μm fiber laser. Thus, InAs--a common semiconductor with favorable plasmonic properties such as a low effective mass--has the potential to become an important building block of optically controlled plasmonic devices operating at infrared frequencies.
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Affiliation(s)
- Martin Wagner
- Department of Physics, University of California, San Diego , La Jolla, California 92093, United States
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22
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Liu MK, Wagner M, Abreu E, Kittiwatanakul S, McLeod A, Fei Z, Goldflam M, Dai S, Fogler MM, Lu J, Wolf SA, Averitt RD, Basov DN. Anisotropic electronic state via spontaneous phase separation in strained vanadium dioxide films. Phys Rev Lett 2013; 111:096602. [PMID: 24033058 DOI: 10.1103/physrevlett.111.096602] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Indexed: 06/02/2023]
Abstract
We resolved the enigma of anisotropic electronic transport in strained vanadium dioxide (VO2) films by inquiring into the role that strain plays in the nanoscale phase separation in the vicinity of the insulator-to-metal transition. The root source of the anisotropy was visualized as the formation of a peculiar unidirectional stripe state which accompanies the phase transition. Furthermore, nanoscale infrared spectroscopy unveils distinct facets of electron-lattice interplay at three different stages of the phase transition. These stages include the initial formation of sparse nonpercolating metallic domains without noticeable involvement of the lattice followed by an electron-lattice coupled anisotropic stripe state close to percolation which ultimately evolves into a nearly isotropic rutile metallic phase. Our results provide a unique mesoscopic perspective for the tunable macroscopic phenomena in strained metal oxide films.
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Affiliation(s)
- M K Liu
- Department of Physics, The University of California at San Diego, La Jolla, California 92093, USA
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23
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Fan K, Hwang HY, Liu M, Strikwerda AC, Sternbach A, Zhang J, Zhao X, Zhang X, Nelson KA, Averitt RD. Nonlinear terahertz metamaterials via field-enhanced carrier dynamics in GaAs. Phys Rev Lett 2013; 110:217404. [PMID: 23745933 DOI: 10.1103/physrevlett.110.217404] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 03/05/2013] [Indexed: 05/14/2023]
Abstract
We demonstrate nonlinear metamaterial split ring resonators (SRRs) on GaAs at terahertz frequencies. For SRRs on doped GaAs films, incident terahertz radiation with peak fields of ~20-160 kV/cm drives intervalley scattering. This reduces the carrier mobility and enhances the SRR LC response due to a conductivity decrease in the doped thin film. Above ~160 kV/cm, electric field enhancement within the SRR gaps leads to efficient impact ionization, increasing the carrier density and the conductivity which, in turn, suppresses the SRR resonance. We demonstrate an increase of up to 10 orders of magnitude in the carrier density in the SRR gaps on semi-insulating GaAs. Furthermore, we show that the effective permittivity can be swept from negative to positive values with an increasing terahertz field strength in the impact ionization regime, enabling new possibilities for nonlinear metamaterials.
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Affiliation(s)
- Kebin Fan
- Department of Mechanical Engineering, Boston University, 110 Cummington Street, Boston, Massachusetts 02215, USA
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Kumar N, Strikwerda AC, Fan K, Zhang X, Averitt RD, Planken PCM, Adam AJL. THz near-field Faraday imaging in hybrid metamaterials. Opt Express 2012; 20:11277-11287. [PMID: 22565750 DOI: 10.1364/oe.20.011277] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report on direct measurements of the magnetic near-field of metamaterial split ring resonators at terahertz frequencies using a magnetic field sensitive material. Specifically, planar split ring resonators are fabricated on a single magneto-optically active terbium gallium garnet crystal. Normally incident terahertz radiation couples to the resonator inducing a magnetic dipole oscillating perpendicular to the crystal surface. Faraday rotation of the polarisation of a near-infrared probe beam directly measures the magnetic near-field with 100 femtosecond temporal resolution and (λ/200) spatial resolution. Numerical simulations suggest that the magnetic field can be enhanced in the plane of the resonator by as much as a factor of 200 compared to the incident field strength. Our results provide a route towards hybrid devices for dynamic magneto-active control of light such as isolators, and highlight the utility of split ring resonators as compact probes of magnetic phenomena in condensed matter.
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Affiliation(s)
- Nishant Kumar
- Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands
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26
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Werley CA, Fan K, Strikwerda AC, Teo SM, Zhang X, Averitt RD, Nelson KA. Time-resolved imaging of near-fields in THz antennas and direct quantitative measurement of field enhancements. Opt Express 2012; 20:8551-8567. [PMID: 22513564 DOI: 10.1364/oe.20.008551] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We investigate the interaction between terahertz waves and resonant antennas with sub-cycle temporal and λ/100 spatial resolution. Depositing antennas on a LiNbO₃ waveguide enables non-invasive electro-optic imaging, quantitative field characterization, and direct measurement of field enhancement (up to 40-fold). The spectral response is determined over a bandwidth spanning from DC across multiple resonances, and distinct behavior is observed in the near- and far-field. The scaling of enhancement and resonant frequency with gap size and antenna length agrees well with simulations.
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Affiliation(s)
- Christopher A Werley
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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27
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Tao H, Brenckle MA, Yang M, Zhang J, Liu M, Siebert SM, Averitt RD, Mannoor MS, McAlpine MC, Rogers JA, Kaplan DL, Omenetto FG. Silk-based conformal, adhesive, edible food sensors. Adv Mater 2012; 24:1067-72. [PMID: 22266768 DOI: 10.1002/adma.201103814] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 12/14/2011] [Indexed: 05/23/2023]
Abstract
An array of passive metamaterial antennas fabricated on all protein-based silk substrates were conformally transferred and adhered to the surface of an apple. This process allows the opportunity for intimate contact of micro- and nanostructures that can probe, and accordingly monitor changes in, their surrounding environment. This provides in situ monitoring of food quality. It is to be noted that this type of sensor consists of all edible and biodegradable components, holding utility and potential relevance for healthcare and food/consumer products and markets.
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Affiliation(s)
- Hu Tao
- Department of Biomedical Engineering, Tufts University, 4 Colby St., Medford, MA 02155, USA
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28
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Iwaszczuk K, Strikwerda AC, Fan K, Zhang X, Averitt RD, Jepsen PU. Flexible metamaterial absorbers for stealth applications at terahertz frequencies. Opt Express 2012; 20:635-43. [PMID: 22274387 DOI: 10.1364/oe.20.000635] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We have wrapped metallic cylinders with strongly absorbing metamaterials. These resonant structures, which are patterned on flexible substrates, smoothly coat the cylinder and give it an electromagnetic response designed to minimize its radar cross section. We compare the normal-incidence, small-beam reflection coefficient with the measurement of the far-field bistatic radar cross section of the sample, using a quasi-planar THz wave with a beam diameter significantly larger than the sample dimensions. In this geometry we demonstrate a near-400-fold reduction of the radar cross section at the design frequency of 0.87 THz. In addition we discuss the effect of finite sample dimensions and the spatial dependence of the reflection spectrum of the metamaterial.
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Affiliation(s)
- Krzysztof Iwaszczuk
- DTU Fotonik—Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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Tao H, Kadlec EA, Strikwerda AC, Fan K, Padilla WJ, Averitt RD, Shaner EA, Zhang X. Microwave and terahertz wave sensing with metamaterials. Opt Express 2011; 19:21620-21626. [PMID: 22109011 DOI: 10.1364/oe.19.021620] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We have designed, fabricated, and characterized metamaterial enhanced bimaterial cantilever pixels for far-infrared detection. Local heating due to absorption from split ring resonators (SRRs) incorporated directly onto the cantilever pixels leads to mechanical deflection which is readily detected with visible light. Highly responsive pixels have been fabricated for detection at 95 GHz and 693 GHz, demonstrating the frequency agility of our technique. We have obtained single pixel responsivities as high as 16,500 V/W and noise equivalent powers of 10(-8) W/Hz(1/2) with these first-generation devices.
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Affiliation(s)
- Hu Tao
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
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Liu MK, Pardo B, Zhang J, Qazilbash MM, Yun SJ, Fei Z, Shin JH, Kim HT, Basov DN, Averitt RD. Photoinduced phase transitions by time-resolved far-infrared spectroscopy in V2O3. Phys Rev Lett 2011; 107:066403. [PMID: 21902347 DOI: 10.1103/physrevlett.107.066403] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Revised: 05/12/2011] [Indexed: 05/31/2023]
Abstract
Using time-resolved far-infrared spectroscopy, we observe multiple routes for photoinduced phase transitions in V(2)O(3). This includes (i) a photothermal antiferromagnetic to paramagnetic transition and (ii) an incipient strain-generated paramagnetic metal to paramagnetic insulator transition, which manifests as coherent oscillations in the far-infrared conductivity. The ∼100 ps conductivity oscillation results from coherent acoustic phonon modulation of the bandwidth W. Our results indicate that poor metals are particularly amenable to coherent strain control of their electronic properties.
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Affiliation(s)
- M K Liu
- Department of Physics, Boston University, Massachusetts 02215, USA
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31
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Tao H, Chieffo LR, Brenckle MA, Siebert SM, Liu M, Strikwerda AC, Fan K, Kaplan DL, Zhang X, Averitt RD, Omenetto FG. Metamaterials on paper as a sensing platform. Adv Mater 2011; 23:3197-201. [PMID: 21638342 PMCID: PMC4128250 DOI: 10.1002/adma.201100163] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2011] [Revised: 04/18/2011] [Indexed: 05/15/2023]
Affiliation(s)
- Hu Tao
- Department of Biomedical Engineering Tufts University 4 Colby St, Medford, MA 02155, USA
| | - Logan R. Chieffo
- Department of Physics, Boston University, 590 Commonwealth Ave, Boston, MA 02215, USA
| | - Mark A. Brenckle
- Department of Biomedical Engineering Tufts University 4 Colby St, Medford, MA 02155, USA
| | - Sean M. Siebert
- Department of Biomedical Engineering Tufts University 4 Colby St, Medford, MA 02155, USA
| | - Mengkun Liu
- Department of Physics, Boston University, 590 Commonwealth Ave, Boston, MA 02215, USA
| | - Andrew C. Strikwerda
- Department of Physics, Boston University, 590 Commonwealth Ave, Boston, MA 02215, USA
| | - Kebin Fan
- Department of Mechanical Engineering, Boston University, 110 Cummington St., Boston, MA 02215, USA
| | - David L. Kaplan
- Department of Biomedical Engineering Tufts University 4 Colby St, Medford, MA 02155, USA
| | - Xin Zhang
- Department of Mechanical Engineering, Boston University, 110 Cummington St., Boston, MA 02215, USA
| | - Richard D. Averitt
- Department of Physics, Boston University, 590 Commonwealth Ave, Boston, MA 02215, USA
| | - Fiorenzo G. Omenetto
- Department of Biomedical Engineering Tufts University 4 Colby St, Medford, MA 02155, USA
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Abstract
We present a detailed study of non-planar or 'stand-up' split ring resonators operating at terahertz frequencies. Based on a facile multilayer electroplating fabrication, this technique can create large area split ring resonators on both rigid substrates and conformally compliant structures. In agreement with simulation results, the characterization of these metamaterials shows a strong response induced purely by the magnetic field. The retrieved parameters also exhibit negative permeability values over a broad frequency span. The extracted parameters exhibit bianisotropy due to the symmetry breaking of the substrate, and this effect is investigated for both single and broad side coupled split rings. Our 3D metamaterial examples pave the way towards numerous potential applications in the terahertz region of the spectrum.
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Affiliation(s)
- Kebin Fan
- Boston University, Department of Mechanical Engineering, 110 Cummington Street, Boston, Massachusetts 02215, USA
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Shrekenhamer D, Rout S, Strikwerda AC, Bingham C, Averitt RD, Sonkusale S, Padilla WJ. High speed terahertz modulation from metamaterials with embedded high electron mobility transistors. Opt Express 2011; 19:9968-75. [PMID: 21643254 DOI: 10.1364/oe.19.009968] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We present a computational and experimental study of a novel terahertz (THz) device resulting from hybridization of metamaterials with pseudomorphic high electron mobility transistors (HEMTs), fabricated in a commercial gallium arsenide (GaAs) process. Monolithic integration of transistors into each unit cell permits modulation at the metamaterial resonant frequency of 0.46 THz. Characterization is performed using a THz time-domain spectrometer (THz-TDS) and we demonstrate switching values over 30%, and THz modulation at frequencies up to 10 megahertz (MHz). Our results demonstrate the viability of incorporating metamaterials into mature semiconductor technologies and establish a new path toward achieving electrically tunable THz devices.
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Affiliation(s)
- David Shrekenhamer
- Department of Physics, Boston College, 140 Commonwealth Avenue, Chestnut Hill, Massachusetts 02467, USA
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35
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Tsioris K, Tao H, Liu M, Hopwood JA, Kaplan DL, Averitt RD, Omenetto FG. Rapid transfer-based micropatterning and dry etching of silk microstructures. Adv Mater 2011; 23:2015-9. [PMID: 21445939 PMCID: PMC3401411 DOI: 10.1002/adma.201004771] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Revised: 02/09/2011] [Indexed: 05/22/2023]
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36
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Whitley VH, Hooks DE, Ramos KJ, Pierce TH, O’Hara JF, Azad AK, Taylor AJ, Barber J, Averitt RD. Orientation Dependent Far-Infrared Terahertz Absorptions in Single Crystal Pentaerythritol Tetranitrate (PETN) Using Terahertz Time-Domain Spectroscopy. J Phys Chem A 2011; 115:439-42. [DOI: 10.1021/jp108388c] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
| | | | | | | | | | | | | | - Jeffrey Barber
- Battelle, Egg Harbor Township, New Jersey 08234, United States
| | - Richard D. Averitt
- Department of Physics, Boston University, Boston, Massachusetts 02215, United States
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Tao H, Amsden JJ, Strikwerda AC, Fan K, Kaplan DL, Zhang X, Averitt RD, Omenetto FG. Metamaterial silk composites at terahertz frequencies. Adv Mater 2010; 22:3527-3531. [PMID: 20665563 DOI: 10.1002/adma.201000412] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Affiliation(s)
- Hu Tao
- Department of Mechanical Engineering, Boston University, 110 Cummington St., Boston, MA, USA
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38
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Tao H, Strikwerda AC, Fan K, Padilla WJ, Zhang X, Averitt RD. Reconfigurable terahertz metamaterials. Phys Rev Lett 2009; 103:147401. [PMID: 19905602 DOI: 10.1103/physrevlett.103.147401] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 09/10/2009] [Indexed: 05/13/2023]
Abstract
We demonstrate reconfigurable anisotropic metamaterials at terahertz frequencies where artificial "atoms" reorient within unit cells in response to an external stimulus. This is accomplished by fabricating planar arrays of split ring resonators on bimaterial cantilevers designed to bend out of plane in response to a thermal stimulus. We observe a marked tunability of the electric and magnetic response as the split ring resonators reorient within their unit cells. Our results demonstrate that adaptive metamaterials offer significant potential to realize novel electromagnetic functionality ranging from thermal detection to reconfigurable cloaks or absorbers.
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Affiliation(s)
- Hu Tao
- Department of Mechanical Engineering, Boston University, 110 Cummington Street, Boston, Massachusetts 02215, USA
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Thorsmølle VK, Averitt RD, Demsar J, Smith DL, Tretiak S, Martin RL, Chi X, Crone BK, Ramirez AP, Taylor AJ. Morphology effectively controls singlet-triplet exciton relaxation and charge transport in organic semiconductors. Phys Rev Lett 2009; 102:017401. [PMID: 19257238 DOI: 10.1103/physrevlett.102.017401] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Indexed: 05/24/2023]
Abstract
We present a comparative study of ultrafast photoconversion dynamics in tetracene (Tc) and pentacene (Pc) single crystals and Pc films using optical pump-probe spectroscopy. Photoinduced absorption in Tc and Pc crystals is activated and temperature-independent, respectively, demonstrating dominant singlet-triplet exciton fission. In Pc films (as well as C60-doped films) this decay channel is suppressed by electron trapping. These results demonstrate the central role of crystallinity and purity in photogeneration processes and will constrain the design of future photovoltaic devices.
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Affiliation(s)
- V K Thorsmølle
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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41
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Strikwerda AC, Fan K, Tao H, Pilon DV, Zhang X, Averitt RD. Comparison of birefringent electric split-ring resonator and meanderline structures as quarter-wave plates at terahertz frequencies. Opt Express 2009; 17:136-149. [PMID: 19129881 DOI: 10.1364/oe.17.000136] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We have fabricated a quarter-wave plate from a single layer of birefringent electric split-ring resonators (ELC). For comparison, an appropriately scaled double layer meanderline structure was fabricated. At the design frequency of 639 GHz, the ELC structure achieves 99.9% circular polarization while the meanderline achieves 99.6%. The me-anderline displays a larger bandwidth of operation, attaining over 99% circular polarization from 615 - 743 GHz, while the ELC achieves 99% from 626 - 660 GHz. However, both are broad enough for use with CW sources making ELCs a more attractive choice due to the ease of fabrication. Both samples are free standing with a total thickness of 70 microm for the meanderline structure and a mere 20 microm for the ELC highlighting the large degree of birefringence exhibited with metamaterial structures.
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42
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Talbayev D, LaForge AD, Trugman SA, Hur N, Taylor AJ, Averitt RD, Basov DN. Magnetic exchange interaction between rare-earth and Mn ions in multiferroic hexagonal manganites. Phys Rev Lett 2008; 101:247601. [PMID: 19113663 DOI: 10.1103/physrevlett.101.247601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Indexed: 05/27/2023]
Abstract
We report a study of magnetic dynamics in multiferroic hexagonal manganite HoMnO3 by far-infrared spectroscopy. The low-temperature magnetic excitation spectrum of HoMnO3 consists of magnetic-dipole transitions of Ho ions within the crystal-field split J = 8 manifold and of the triangular antiferromagnetic resonance of Mn ions. We determine the effective spin Hamiltonian for the Ho ion ground state. The magnetic-field splitting of the Mn antiferromagnetic resonance allows us to measure the magnetic exchange coupling between the rare-earth and Mn ions.
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Affiliation(s)
- D Talbayev
- Center for Integrated Nanotechnologies, MS K771, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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43
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Bingham CM, Tao H, Liu X, Averitt RD, Zhang X, Padilla WJ. Planar wallpaper group metamaterials for novel terahertz applications. Opt Express 2008; 16:18565-75. [PMID: 19581942 DOI: 10.1364/oe.16.018565] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We present novel metamaterial structures based upon various planar wallpaper groups, in both hexagonal and square unit cells. An investigation of metamaterials consisting of one, two, and three unique sub-lattices with resonant frequencies in the terahertz (THz) was performed. We describe the theory, perform simulations, and conduct experiments to characterize these multiple element metamaterials. A method for using these new structures as a means for bio/chemical hazard detection, as well as electromagnetic signature control is proposed.
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44
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Talbayev D, Trugman SA, Balatsky AV, Kimura T, Taylor AJ, Averitt RD. Detection of coherent magnons via ultrafast pump-probe reflectance spectroscopy in multiferroic Ba0.6Sr1.4Zn2Fe12O22. Phys Rev Lett 2008; 101:097603. [PMID: 18851660 DOI: 10.1103/physrevlett.101.097603] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2007] [Indexed: 05/26/2023]
Abstract
We report the detection of a magnetic resonance mode in multiferroic Ba0.6Sr1.4Zn2Fe12O22 using time-domain pump-probe reflectance spectroscopy. Magnetic sublattice precession is coherently excited via picosecond thermal modification of the exchange energy. Importantly, this precession is recorded as a change in reflectance caused by the dynamic magnetoelectric effect. Thus, transient reflectance provides a sensitive probe of magnetization dynamics in materials with strong magnetoelectric coupling, such as multiferroics, revealing new possibilities for application in spintronics and ultrafast manipulation of magnetic moments.
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Affiliation(s)
- D Talbayev
- Center for Integrated Nanotechnologies, MS K771, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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45
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Chen HT, Lu H, Azad AK, Averitt RD, Gossard AC, Trugman SA, O'Hara JF, Taylor AJ. Electronic control of extraordinary terahertz transmission through subwavelength metal hole arrays. Opt Express 2008; 16:7641-7648. [PMID: 18545471 DOI: 10.1364/oe.16.007641] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We describe the electronic control of extraordinary terahertz transmission through subwavelength metal hole arrays fabricated on doped semiconductor substrates. The hybrid metal-semiconductor forms a Schottky diode structure, where the active depletion region modifies the substrate conductivity in real-time by applying an external voltage bias. This enables effective control of the resonance enhanced terahertz transmission. Our proof of principle device achieves an intensity modulation depth of 52% by changing the voltage bias between 0 and 16 volts. Further optimization may result in improvement of device performance and practical applications. This approach can be also translated to the other optical frequency ranges.
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Affiliation(s)
- Hou-Tong Chen
- Los Alamos National Laboratory, MPA-CINT, MS K771, Los Alamos, New Mexico 87545, USA.
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46
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Tao H, Landy NI, Bingham CM, Zhang X, Averitt RD, Padilla WJ. A metamaterial absorber for the terahertz regime: design, fabrication and characterization. Opt Express 2008; 16:7181-8. [PMID: 18545422 DOI: 10.1364/oe.16.007181] [Citation(s) in RCA: 258] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We present a metamaterial that acts as a strongly resonant absorber at terahertz frequencies. Our design consists of a bilayer unit cell which allows for maximization of the absorption through independent tuning of the electrical permittivity and magnetic permeability. An experimental absorptivity of 70% at 1.3 terahertz is demonstrated. We utilize only a single unit cell in the propagation direction, thus achieving an absorption coefficient alpha = 2000 cm(-1). These metamaterials are promising candidates as absorbing elements for thermally based THz imaging, due to their relatively low volume, low density, and narrow band response.
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Affiliation(s)
- Hu Tao
- Department of Manufacturing Engineering, Boston University,Brookline, Massachusetts 02446, USA
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47
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Prasankumar RP, Attaluri RS, Averitt RD, Urayama J, Weisse-Bernstein N, Rotella P, Stintz AD, Krishna S, Taylor AJ. Ultrafast carrier dynamics in an InAs/InGaAs quantum dots-in-a-well heterostructure. Opt Express 2008; 16:1165-1173. [PMID: 18542190 DOI: 10.1364/oe.16.001165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Ultrafast differential transmission spectroscopy is used to explore temperature-dependent carrier dynamics in an InAs/InGaAs quantum dots-in-a-well heterostructure. Electron-hole pairs are optically injected into the three dimensional GaAs barriers, after which we monitor carrier relaxation into the two dimensional InGaAs quantum wells and the zero dimensional InAs quantum dots by tuning the probe photon energy. We find that carrier capture and relaxation are dominated by Auger carrier-carrier scattering at low temperatures, with thermal emission playing an increasing role with temperature. Our experiments provide essential insight into carrier relaxation across multiple spatial dimensions.
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Affiliation(s)
- R P Prasankumar
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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48
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Burch KS, Chia EEM, Talbayev D, Sales BC, Mandrus D, Taylor AJ, Averitt RD. Coupling between an optical phonon and the Kondo effect. Phys Rev Lett 2008; 100:026409. [PMID: 18232899 DOI: 10.1103/physrevlett.100.026409] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Indexed: 05/25/2023]
Abstract
We explore the ultrafast optical response of Yb14MnSb11, providing further evidence that this compound is the first d-electron, ferromagnetic, underscreened Kondo lattice. These results also provide the first demonstration of coupling between an optical phonon mode and the Kondo effect.
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Affiliation(s)
- K S Burch
- Los Alamos National Laboratory, MS K771, MPA-CINT, Los Alamos, New Mexico 87545, USA.
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Hilton DJ, Prasankumar RP, Fourmaux S, Cavalleri A, Brassard D, El Khakani MA, Kieffer JC, Taylor AJ, Averitt RD. Enhanced photosusceptibility near Tc for the light-induced insulator-to-metal phase transition in vanadium dioxide. Phys Rev Lett 2007; 99:226401. [PMID: 18233305 DOI: 10.1103/physrevlett.99.226401] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Indexed: 05/22/2023]
Abstract
We use optical-pump terahertz-probe spectroscopy to investigate the near-threshold behavior of the photoinduced insulator-to-metal (IM) transition in vanadium dioxide thin films. Upon approaching Tc a reduction in the fluence required to drive the IM transition is observed, consistent with a softening of the insulating state due to an increasing metallic volume fraction (below the percolation limit). This phase coexistence facilitates the growth of a homogeneous metallic conducting phase following superheating via photoexcitation. A simple dynamic model using Bruggeman effective medium theory describes the observed initial condition sensitivity.
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Affiliation(s)
- D J Hilton
- Center for Integrated Nanotechnologies, MS K771, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Chia EEM, Zhu JX, Talbayev D, Averitt RD, Taylor AJ, Oh KH, Jo IS, Lee SI. Observation of competing order in a high-Tc superconductor using femtosecond optical pulses. Phys Rev Lett 2007; 99:147008. [PMID: 17930711 DOI: 10.1103/physrevlett.99.147008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Indexed: 05/25/2023]
Abstract
We present studies of the photoexcited quasiparticle dynamics in Tl(2)Ba(2)Ca(2)Cu(3)O(y) (Tl-2223) using femtosecond optical techniques. Deep into the superconducting state (below 40 K), a dramatic change occurs in the temporal dynamics associated with photoexcited quasiparticles rejoining the condensate. This is suggestive of entry into a coexistence phase which, as our analysis reveals, opens a gap in the density of states (in addition to the superconducting gap), and furthermore, competes with superconductivity resulting in a depression of the superconducting gap.
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Affiliation(s)
- Elbert E M Chia
- MPA-CINT and T-11, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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