1
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Huber M, Lin Y, Marini G, Moreschini L, Jozwiak C, Bostwick A, Calandra M, Lanzara A. Ultrafast creation of a light-induced semimetallic state in strongly excited 1T-TiSe 2. SCIENCE ADVANCES 2024; 10:eadl4481. [PMID: 38728393 PMCID: PMC11086600 DOI: 10.1126/sciadv.adl4481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 04/09/2024] [Indexed: 05/12/2024]
Abstract
Screening, a ubiquitous phenomenon associated with the shielding of electric fields by surrounding charges, has been widely adopted as a means to modify a material's properties. While most studies have relied on static changes of screening through doping or gating thus far, here we demonstrate that screening can also drive the onset of distinct quantum states on the ultrafast timescale. By using time- and angle-resolved photoemission spectroscopy, we show that intense optical excitation can drive 1T-TiSe2, a prototypical charge density wave material, almost instantly from a gapped into a semimetallic state. By systematically comparing changes in band structure over time and excitation strength with theoretical calculations, we find that the appearance of this state is likely caused by a dramatic reduction of the screening length. In summary, this work showcases how optical excitation enables the screening-driven design of a nonequilibrium semimetallic phase in TiSe2, possibly providing a general pathway into highly screened phases in other strongly correlated materials.
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Affiliation(s)
- Maximilian Huber
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Yi Lin
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487, USA
| | - Giovanni Marini
- Graphene Labs, Fondazione Istituto Italiano di Tecnologia, I-16163 Genova, Italy
- Department of Physics, University of Trento, 38123 Povo, Italy
| | - Luca Moreschini
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Chris Jozwiak
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Aaron Bostwick
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Matteo Calandra
- Graphene Labs, Fondazione Istituto Italiano di Tecnologia, I-16163 Genova, Italy
- Department of Physics, University of Trento, 38123 Povo, Italy
- Sorbonne Universite, CNRS, Institut des Nanosciences de Paris, F-75252 Paris, France
| | - Alessandra Lanzara
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Physics Department, University of California, Berkeley, Berkeley, CA 94720, USA
- Kavli Energy NanoScience Institute, Berkeley, CA 94720, USA
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2
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Bange JP, Schmitt D, Bennecke W, Meneghini G, AlMutairi A, Watanabe K, Taniguchi T, Steil D, Steil S, Weitz RT, Jansen GSM, Hofmann S, Brem S, Malic E, Reutzel M, Mathias S. Probing electron-hole Coulomb correlations in the exciton landscape of a twisted semiconductor heterostructure. SCIENCE ADVANCES 2024; 10:eadi1323. [PMID: 38324690 PMCID: PMC10849592 DOI: 10.1126/sciadv.adi1323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 01/10/2024] [Indexed: 02/09/2024]
Abstract
In two-dimensional semiconductors, cooperative and correlated interactions determine the material's excitonic properties and can even lead to the creation of correlated states of matter. Here, we study the fundamental two-particle correlated exciton state formed by the Coulomb interaction between single-particle holes and electrons. We find that the ultrafast transfer of an exciton's hole across a type II band-aligned semiconductor heterostructure leads to an unexpected sub-200-femtosecond upshift of the single-particle energy of the electron being photoemitted from the two-particle exciton state. While energy relaxation usually leads to an energetic downshift of the spectroscopic signature, we show that this upshift is a clear fingerprint of the correlated interaction of the electron and hole parts of the exciton. In this way, time-resolved photoelectron spectroscopy is straightforwardly established as a powerful method to access electron-hole correlations and cooperative behavior in quantum materials. Our work highlights this capability and motivates the future study of optically inaccessible correlated excitonic and electronic states of matter.
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Affiliation(s)
- Jan Philipp Bange
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - David Schmitt
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Wiebke Bennecke
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Giuseppe Meneghini
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
| | | | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Daniel Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Sabine Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - R. Thomas Weitz
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- International Center for Advanced Studies of Energy Conversion (ICASEC), University of Göttingen, Göttingen, Germany
| | - G. S. Matthijs Jansen
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Stephan Hofmann
- Department of Engineering, University of Cambridge, Cambridge CB3 0FA, UK
| | - Samuel Brem
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
| | - Ermin Malic
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
- Department of Physics, Chalmers University of Technology, Gothenburg, Sweden
| | - Marcel Reutzel
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Stefan Mathias
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- International Center for Advanced Studies of Energy Conversion (ICASEC), University of Göttingen, Göttingen, Germany
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3
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Huang Y, Lv S, Liu H, Cheng Q, Biao Y, Lu H, Lin X, Wang Z, Yang H, Chen H, Weng YX. Observation of photoinduced polarons in semimetal 1T-TiSe 2. NANOTECHNOLOGY 2023; 34:235707. [PMID: 36877995 DOI: 10.1088/1361-6528/acc188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 03/05/2023] [Indexed: 06/18/2023]
Abstract
In this work, ultrafast carrier dynamics of mechanically exfoliated 1T-TiSe2flakes from the high-quality single crystals with self-intercalated Ti atoms are investigated by femtosecond transient absorption spectroscopy. The observed coherent acoustic and optical phonon oscillations after ultrafast photoexcitation reveal the strong electron-phonon coupling in 1T-TiSe2. The ultrafast carrier dynamics probed in both visible and mid-infrared regions indicate that some photogenerated carriers localize near the intercalated Ti atoms and form small polarons rapidly within several picoseconds after photoexcitation due to the strong and short-range electron-phonon coupling. The formation of polarons leads to a reduction of carrier mobility and a long-time relaxation process of photoexcited carriers for several nanoseconds. The formation and dissociation rates of the photoinduced polarons are dependent on both the pump fluence and the thickness of TiSe2sample. This work offers new insights into the photogenerated carrier dynamics of 1T-TiSe2, and emphasizes the effects of intercalated atoms on the electron and lattice dynamics after photoexcitation.
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Affiliation(s)
- Yin Huang
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Senhao Lv
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Heyuan Liu
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Qiuzhen Cheng
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Yi Biao
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Hongliang Lu
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Xiao Lin
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Zhuan Wang
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Haitao Yang
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, People's Republic of China
| | - Hailong Chen
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, People's Republic of China
| | - Yu-Xiang Weng
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, People's Republic of China
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4
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Huber M, Lin Y, Dale N, Sailus R, Tongay S, Kaindl RA, Lanzara A. Revealing the order parameter dynamics of 1T-TiSe[Formula: see text] following optical excitation. Sci Rep 2022; 12:15860. [PMID: 36151110 PMCID: PMC9508156 DOI: 10.1038/s41598-022-19319-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 08/26/2022] [Indexed: 11/09/2022] Open
Abstract
The formation of a charge density wave state is characterized by an order parameter. The way it is established provides unique information on both the role that correlation plays in driving the charge density wave formation and the mechanism behind its formation. Here we use time and angle resolved photoelectron spectroscopy to optically perturb the charge-density phase in 1T-TiSe[Formula: see text] and follow the recovery of its order parameter as a function of energy, momentum and excitation density. Our results reveal that two distinct orders contribute to the gap formation, a CDW order and pseudogap-like order, manifested by an overall robustness to optical excitation. A detailed analysis of the magnitude of the the gap as a function of excitation density and delay time reveals the excitonic long-range nature of the CDW gap and the short-range Jahn-Teller character of the pseudogap order. In contrast to the gap, the intensity of the folded Se[Formula: see text]* band can only give access to the excitonic order. These results provide new information into the the long standing debate on the origin of the gap in TiSe[Formula: see text] and place it in the same context of other quantum materials where a pseudogap phase appears to be a precursor of long-range order.
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Affiliation(s)
- Maximilian Huber
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Yi Lin
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Nicholas Dale
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
- Physics Department, University of California Berkeley, Berkeley, CA 94720 USA
| | - Renee Sailus
- Materials Science and Engineering Department, Arizona State University, Phoenix, AZ 85281 USA
| | - Sefaattin Tongay
- Materials Science and Engineering Department, Arizona State University, Phoenix, AZ 85281 USA
| | - Robert A. Kaindl
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
- Department of Physics and CXFEL Labs, Arizona State University, Phoenix, AZ 85287 USA
| | - Alessandra Lanzara
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
- Physics Department, University of California Berkeley, Berkeley, CA 94720 USA
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5
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Düvel M, Merboldt M, Bange JP, Strauch H, Stellbrink M, Pierz K, Schumacher HW, Momeni D, Steil D, Jansen GSM, Steil S, Novko D, Mathias S, Reutzel M. Far-from-Equilibrium Electron-Phonon Interactions in Optically Excited Graphene. NANO LETTERS 2022; 22:4897-4904. [PMID: 35649249 DOI: 10.1021/acs.nanolett.2c01325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Comprehending far-from-equilibrium many-body interactions is one of the major goals of current ultrafast condensed matter physics research. Here, a particularly interesting but barely understood situation occurs during a strong optical excitation, where the electron and phonon systems can be significantly perturbed and the quasiparticle distributions cannot be described with equilibrium functions. In this work, we use time- and angle-resolved photoelectron spectroscopy to study such far-from-equilibrium many-body interactions for the prototypical material graphene. In accordance with theoretical simulations, we find remarkable transient renormalizations of the quasiparticle self-energy caused by the photoinduced nonequilibrium conditions. These observations can be understood by ultrafast scatterings between nonequilibrium electrons and strongly coupled optical phonons, which signify the crucial role of ultrafast nonequilibrium dynamics on many-body interactions. Our results advance the understanding of many-body physics in extreme conditions, which is important for any endeavor to optically manipulate or create non-equilibrium states of matter.
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Affiliation(s)
- Marten Düvel
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Marco Merboldt
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Jan Philipp Bange
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Hannah Strauch
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Michael Stellbrink
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Klaus Pierz
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
| | | | - Davood Momeni
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
| | - Daniel Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - G S Matthijs Jansen
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Sabine Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Dino Novko
- Institute of Physics, HR-10000 Zagreb, Croatia
| | - Stefan Mathias
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- International Center for Advanced Studies of Energy Conversion (ICASEC), University of Göttingen, 37077 Göttingen, Germany
| | - Marcel Reutzel
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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6
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Tian X, Wei R, Ma Z, Qiu J. Broadband Nonlinear Optical Absorption Induced by Bandgap Renormalization in CVD-Grown Monolayer MoSe 2. ACS APPLIED MATERIALS & INTERFACES 2022; 14:8274-8281. [PMID: 35113533 DOI: 10.1021/acsami.1c23053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Optical modulation on ultrashort time scales is both of central importance and an essential operation for applications in photonics and optoelectronics. Here, with a giant bandgap renormalization due to a high density of carrier injected by a femtosecond pulse, we realize an expected broadband saturable absorption in chemical vapor deposition grown monolayer transition-metal dichalcogenide MoSe2. Our findings reveal the band edge shift from ∼1.53 to ∼0.52 eV under the pump excitation of 0.80 eV, which is induced by the nonequilibrium occupation of electron-hole states after a Mott transition as well as the increase of carrier temperature.
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Affiliation(s)
| | - Rongfei Wei
- Department of Physics, Zhejiang Normal University, Jinhua, Zhejiang 321004, P.R. China
| | - Zhijun Ma
- Zhejiang Laboratory, Hangzhou 311100, P.R. China
| | - Jianrong Qiu
- State Key Laboratory of Modern Optical Instrumentation, College of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, P.R. China
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7
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Otto MR, Pöhls JH, René de Cotret LP, Stern MJ, Sutton M, Siwick BJ. Mechanisms of electron-phonon coupling unraveled in momentum and time: The case of soft phonons in TiSe 2. SCIENCE ADVANCES 2021; 7:7/20/eabf2810. [PMID: 33980488 PMCID: PMC8115930 DOI: 10.1126/sciadv.abf2810] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 03/26/2021] [Indexed: 06/12/2023]
Abstract
The complex coupling between charge carriers and phonons is responsible for diverse phenomena in condensed matter. We apply ultrafast electron diffuse scattering to unravel electron-phonon coupling phenomena in 1T-TiSe2 in both momentum and time. We are able to distinguish effects due to the real part of the many-body bare electronic susceptibility, [Formula: see text], from those due to the electron-phonon coupling vertex, g q , by following the response of semimetallic (normal-phase) 1T-TiSe2 to the selective photo-doping of carriers into the electron pocket at the Fermi level. Quasi-impulsive and wave vector-specific renormalization of soft zone-boundary phonon frequencies (stiffening) is observed, followed by wave vector-independent electron-phonon equilibration. These results unravel the underlying mechanisms driving the phonon softening that is associated with the charge density wave transition at lower temperatures.
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Affiliation(s)
- Martin R Otto
- Department of Physics, Center for the Physics of Materials, McGill University, 3600 rue Université, Montréal, Québec H3A 2T8, Canada
| | - Jan-Hendrik Pöhls
- Department of Physics, Center for the Physics of Materials, McGill University, 3600 rue Université, Montréal, Québec H3A 2T8, Canada
| | - Laurent P René de Cotret
- Department of Physics, Center for the Physics of Materials, McGill University, 3600 rue Université, Montréal, Québec H3A 2T8, Canada
| | - Mark J Stern
- Department of Physics, Center for the Physics of Materials, McGill University, 3600 rue Université, Montréal, Québec H3A 2T8, Canada
| | - Mark Sutton
- Department of Physics, Center for the Physics of Materials, McGill University, 3600 rue Université, Montréal, Québec H3A 2T8, Canada
| | - Bradley J Siwick
- Department of Physics, Center for the Physics of Materials, McGill University, 3600 rue Université, Montréal, Québec H3A 2T8, Canada.
- Department of Chemistry, McGill University, 801 rue Sherbrooke Ouest, Montréal, Québec H3A 0B8, Canada
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8
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Biswas D, Jones AJH, Majchrzak P, Choi BK, Lee TH, Volckaert K, Feng J, Marković I, Andreatta F, Kang CJ, Kim HJ, Lee IH, Jozwiak C, Rotenberg E, Bostwick A, Sanders CE, Zhang Y, Karras G, Chapman RT, Wyatt AS, Springate E, Miwa JA, Hofmann P, King PDC, Chang YJ, Lanatà N, Ulstrup S. Ultrafast Triggering of Insulator-Metal Transition in Two-Dimensional VSe 2. NANO LETTERS 2021; 21:1968-1975. [PMID: 33600187 DOI: 10.1021/acs.nanolett.0c04409] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The transition-metal dichalcogenide VSe2 exhibits an increased charge density wave transition temperature and an emerging insulating phase when thinned to a single layer. Here, we investigate the interplay of electronic and lattice degrees of freedom that underpin these phases in single-layer VSe2 using ultrafast pump-probe photoemission spectroscopy. In the insulating state, we observe a light-induced closure of the energy gap, which we disentangle from the ensuing hot carrier dynamics by fitting a model spectral function to the time-dependent photoemission intensity. This procedure leads to an estimated time scale of 480 fs for the closure of the gap, which suggests that the phase transition in single-layer VSe2 is driven by electron-lattice interactions rather than by Mott-like electronic effects. The ultrafast optical switching of these interactions in SL VSe2 demonstrates the potential for controlling phase transitions in 2D materials with light.
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Affiliation(s)
- Deepnarayan Biswas
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Alfred J H Jones
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Paulina Majchrzak
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Byoung Ki Choi
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
| | - Tsung-Han Lee
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08856, United States
| | - Klara Volckaert
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Jiagui Feng
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, U.K
- Suzhou Institute of Nano-Tech. and Nanobionics (SINANO), CAS, 398 Ruoshui Road, SEID, SIP, Suzhou 215123, China
| | - Igor Marković
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, U.K
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Federico Andreatta
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Chang-Jong Kang
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08856, United States
| | - Hyuk Jin Kim
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
| | - In Hak Lee
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
| | - Chris Jozwiak
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Eli Rotenberg
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Aaron Bostwick
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Charlotte E Sanders
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Yu Zhang
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Gabriel Karras
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Richard T Chapman
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Adam S Wyatt
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Emma Springate
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Jill A Miwa
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Philip Hofmann
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Phil D C King
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, U.K
| | - Young Jun Chang
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
- Department of Smart Cities, University of Seoul, Seoul, 02504, Republic of Korea
| | - Nicola Lanatà
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
- Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, 10691 Stockholm, Sweden
| | - Søren Ulstrup
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
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9
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Yang LX, Rohde G, Hanff K, Stange A, Xiong R, Shi J, Bauer M, Rossnagel K. Bypassing the Structural Bottleneck in the Ultrafast Melting of Electronic Order. PHYSICAL REVIEW LETTERS 2020; 125:266402. [PMID: 33449703 DOI: 10.1103/physrevlett.125.266402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 11/23/2020] [Indexed: 06/12/2023]
Abstract
Impulsive optical excitation generally results in a complex nonequilibrium electron and lattice dynamics that involves multiple processes on distinct timescales, and a common conception is that for times shorter than about 100 fs the gap in the electronic spectrum is not seriously affected by lattice vibrations. Here, however, by directly monitoring the photoinduced collapse of the spectral gap in a canonical charge-density-wave material, the blue bronze Rb_{0.3}MoO_{3}, we find that ultrafast (∼60 fs) vibrational disordering due to efficient hot-electron energy dissipation quenches the gap significantly faster than the typical structural bottleneck time corresponding to one half-cycle oscillation (∼315 fs) of the coherent charge-density-wave amplitude mode. This result not only demonstrates the importance of incoherent lattice motion in the photoinduced quenching of electronic order, but also resolves the perennial debate about the nature of the spectral gap in a coupled electron-lattice system.
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Affiliation(s)
- L X Yang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
| | - G Rohde
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - K Hanff
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - A Stange
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - R Xiong
- Department of Physics, Wuhan University, Wuhan 430072, People's Republic of China
| | - J Shi
- Department of Physics, Wuhan University, Wuhan 430072, People's Republic of China
| | - M Bauer
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - K Rossnagel
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
- Ruprecht-Haensel-Labor, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
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10
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Maklar J, Dong S, Beaulieu S, Pincelli T, Dendzik M, Windsor YW, Xian RP, Wolf M, Ernstorfer R, Rettig L. A quantitative comparison of time-of-flight momentum microscopes and hemispherical analyzers for time- and angle-resolved photoemission spectroscopy experiments. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:123112. [PMID: 33379994 DOI: 10.1063/5.0024493] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/26/2020] [Indexed: 06/12/2023]
Abstract
Time-of-flight-based momentum microscopy has a growing presence in photoemission studies, as it enables parallel energy- and momentum-resolved acquisition of the full photoelectron distribution. Here, we report table-top extreme ultraviolet time- and angle-resolved photoemission spectroscopy (trARPES) featuring both a hemispherical analyzer and a momentum microscope within the same setup. We present a systematic comparison of the two detection schemes and quantify experimentally relevant parameters, including pump- and probe-induced space-charge effects, detection efficiency, photoelectron count rates, and depth of focus. We highlight the advantages and limitations of both instruments based on exemplary trARPES measurements of bulk WSe2. Our analysis demonstrates the complementary nature of the two spectrometers for time-resolved ARPES experiments. Their combination in a single experimental apparatus allows us to address a broad range of scientific questions with trARPES.
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Affiliation(s)
- J Maklar
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - S Dong
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - S Beaulieu
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - T Pincelli
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - M Dendzik
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Y W Windsor
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - R P Xian
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - M Wolf
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - R Ernstorfer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - L Rettig
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
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11
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Keunecke M, Möller C, Schmitt D, Nolte H, Jansen GSM, Reutzel M, Gutberlet M, Halasi G, Steil D, Steil S, Mathias S. Time-resolved momentum microscopy with a 1 MHz high-harmonic extreme ultraviolet beamline. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:063905. [PMID: 32611056 DOI: 10.1063/5.0006531] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 06/04/2020] [Indexed: 06/11/2023]
Abstract
Recent progress in laser-based high-repetition rate extreme ultraviolet (EUV) light sources and multidimensional photoelectron spectroscopy enables the build-up of a new generation of time-resolved photoemission experiments. Here, we present a setup for time-resolved momentum microscopy driven by a 1 MHz fs EUV table-top light source optimized for the generation of 26.5 eV photons. The setup provides simultaneous access to the temporal evolution of the photoelectron's kinetic energy and in-plane momentum. We discuss opportunities and limitations of our new experiment based on a series of static and time-resolved measurements on graphene.
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Affiliation(s)
- Marius Keunecke
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Christina Möller
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - David Schmitt
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Hendrik Nolte
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - G S Matthijs Jansen
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Marcel Reutzel
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Marie Gutberlet
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Gyula Halasi
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Daniel Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Sabine Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Stefan Mathias
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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12
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Lian C, Zhang SJ, Hu SQ, Guan MX, Meng S. Ultrafast charge ordering by self-amplified exciton-phonon dynamics in TiSe 2. Nat Commun 2020; 11:43. [PMID: 31896745 PMCID: PMC6940384 DOI: 10.1038/s41467-019-13672-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Accepted: 11/14/2019] [Indexed: 11/24/2022] Open
Abstract
The origin of charge density waves (CDWs) in TiSe\documentclass[12pt]{minimal}
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\begin{document}$${}_{2}$$\end{document}2 has long been debated, mainly due to the difficulties in identifying the timescales of the excitonic pairing and electron–phonon coupling (EPC). Without a time-resolved and microscopic mechanism, one has to assume simultaneous appearance of CDW and periodic lattice distortions (PLD). Here, we accomplish a complete separation of ultrafast exciton and PLD dynamics and unravel their interplay in our real-time time-dependent density functional theory simulations. We find that laser pulses knock off the exciton order and induce a homogeneous bonding–antibonding transition in the initial 20 fs, then the weakened electronic order triggers ionic movements antiparallel to the original PLD. The EPC comes into play after the initial 20 fs, and the two processes mutually amplify each other leading to a complete inversion of CDW ordering. The self-amplified dynamics reproduces the evolution of band structures in agreement with photoemission experiments. Hence we resolve the key processes in the initial dynamics of CDWs that help elucidate the underlying mechanism. The physical origins of charge density waves in 1T-TiSe2 and their response to ultrafast excitation have long been a topic of theoretical and experimental debate. Here the authors present an ab initio theory that successfully captures the observed dynamics of charge density wave formation.
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Affiliation(s)
- Chao Lian
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Sheng-Jie Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Shi-Qi Hu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Meng-Xue Guan
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Sheng Meng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China. .,School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, P. R. China. .,Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, P. R. China.
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13
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Wei R, Tian X, Yang L, Yang D, Ma Z, Guo H, Qiu J. Ultrafast and large optical nonlinearity of a TiSe 2 saturable absorber in the 2 μm wavelength region. NANOSCALE 2019; 11:22277-22285. [PMID: 31570910 DOI: 10.1039/c9nr06374a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The non-equilibrium state of correlated electron materials is crucial for both scientific research and practical applications in optoelectronic and photonic devices. Because of the weak optical nonlinearity of most materials even under a dense optical excitation, it is desirable to achieve a significant nonlinear optical response with ultrafast and large optical nonlinearity utilizing a common material. Here, an ultrafast response and large optical nonlinearity induced by non-equilibrium electrons in typical transition metal dichalcogenides, TiSe2, are investigated in the 1.55-2.0 μm wavelength region. Significantly, we observe an ultrafast transient dynamics of 491 femtoseconds as well as a large optical nonlinearity with a saturable coefficient of -0.17 cm GW-1 (1.55 μm) and -0.10 cm GW-1 (2.0 μm). Upon increasing pump fluence, TiSe2 exhibits an enhanced bleaching response amplitude up to 563%. Furthermore, a stable Q-switched fiber laser in the 2.0 μm wavelength region is achieved by employing the TiSe2-saturable absorber. The findings offer the potential design to enhance the optical nonlinearity via non-equilibrium electrons for advanced photonic devices.
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Affiliation(s)
- Rongfei Wei
- Department of Physics, Zhejiang Normal University, Jinhua, Zhejiang 321004, China.
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14
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Chávez-Cervantes M, Topp GE, Aeschlimann S, Krause R, Sato SA, Sentef MA, Gierz I. Charge Density Wave Melting in One-Dimensional Wires with Femtosecond Subgap Excitation. PHYSICAL REVIEW LETTERS 2019; 123:036405. [PMID: 31386485 DOI: 10.1103/physrevlett.123.036405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 05/16/2019] [Indexed: 06/10/2023]
Abstract
Charge density waves (CDWs) are symmetry-broken ground states that commonly occur in low-dimensional metals due to strong electron-electron and/or electron-phonon coupling. The nonequilibrium carrier distribution established via photodoping with femtosecond laser pulses readily quenches these ground states and induces an ultrafast insulator-to-metal phase transition. To date, CDW melting has been mainly investigated in the single-photon regime with pump photon energies bigger than the gap size. The recent development of strong-field midinfrared sources now enables the investigation of CDW dynamics following subgap excitation. Here we excite prototypical one-dimensional indium wires with a CDW gap of ∼300 meV with midinfrared pulses at ℏω=190 meV with MV/cm field strength and probe the transient electronic structure with time- and angle-resolved photoemission spectroscopy. We find that the CDW gap is filled on a timescale short compared to our temporal resolution of 300 fs and that the band structure changes are completed within ∼1 ps. Supported by a minimal theoretical model we attribute our findings to multiphoton absorption across the CDW gap.
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Affiliation(s)
- M Chávez-Cervantes
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - G E Topp
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - S Aeschlimann
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - R Krause
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - S A Sato
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - M A Sentef
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - I Gierz
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
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15
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Stadtmüller B, Emmerich S, Jungkenn D, Haag N, Rollinger M, Eich S, Maniraj M, Aeschlimann M, Cinchetti M, Mathias S. Strong modification of the transport level alignment in organic materials after optical excitation. Nat Commun 2019; 10:1470. [PMID: 30931921 PMCID: PMC6443800 DOI: 10.1038/s41467-019-09136-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 02/25/2019] [Indexed: 11/20/2022] Open
Abstract
Organic photovoltaic devices operate by absorbing light and generating current. These two processes are governed by the optical and transport properties of the organic semiconductor. Despite their common microscopic origin-the electronic structure-disclosing their dynamical interplay is far from trivial. Here we address this issue by time-resolved photoemission to directly investigate the correlation between the optical and transport response in organic materials. We reveal that optical generation of non-interacting excitons in a fullerene film results in a substantial redistribution of all transport levels (within 0.4 eV) of the non-excited molecules. As all observed dynamics evolve on identical timescales, we conclude that optical and transport properties are completely interlinked. This finding paves the way for developing novel concepts for transport level engineering on ultrafast time scales that could lead to novel functional optoelectronic devices.
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Affiliation(s)
- Benjamin Stadtmüller
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany.
- Graduate School of Excellence Materials Science in Mainz, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany.
| | - Sebastian Emmerich
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany
- Graduate School of Excellence Materials Science in Mainz, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany
| | - Dominik Jungkenn
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany
| | - Norman Haag
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany
| | - Markus Rollinger
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany
| | - Steffen Eich
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany
| | - Mahalingam Maniraj
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany
| | - Martin Aeschlimann
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany
| | - Mirko Cinchetti
- Experimentelle Physik VI, Technische Universität Dortmund, 44221, Dortmund, Germany
| | - Stefan Mathias
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany
- International Center for Advanced Studies of Energy Conversion (ICASEC), Georg-August-Universität Göttingen, 37077, Göttingen, Germany
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16
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Buss JH, Wang H, Xu Y, Maklar J, Joucken F, Zeng L, Stoll S, Jozwiak C, Pepper J, Chuang YD, Denlinger JD, Hussain Z, Lanzara A, Kaindl RA. A setup for extreme-ultraviolet ultrafast angle-resolved photoelectron spectroscopy at 50-kHz repetition rate. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:023105. [PMID: 30831755 DOI: 10.1063/1.5079677] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Time- and angle-resolved photoelectron spectroscopy (trARPES) is a powerful method to track the ultrafast dynamics of quasiparticles and electronic bands in energy and momentum space. We present a setup for trARPES with 22.3 eV extreme-ultraviolet (XUV) femtosecond pulses at 50-kHz repetition rate, which enables fast data acquisition and access to dynamics across momentum space with high sensitivity. The design and operation of the XUV beamline, pump-probe setup, and ultra-high vacuum endstation are described in detail. By characterizing the effect of space-charge broadening, we determine an ultimate source-limited energy resolution of 60 meV, with typically 80-100 meV obtained at 1-2 × 1010 photons/s probe flux on the sample. The instrument capabilities are demonstrated via both equilibrium and time-resolved ARPES studies of transition-metal dichalcogenides. The 50-kHz repetition rate enables sensitive measurements of quasiparticles at low excitation fluences in semiconducting MoSe2, with an instrumental time resolution of 65 fs. Moreover, photo-induced phase transitions can be driven with the available pump fluence, as shown by charge density wave melting in 1T-TiSe2. The high repetition-rate setup thus provides a versatile platform for sensitive XUV trARPES, from quenching of electronic phases down to the perturbative limit.
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Affiliation(s)
- Jan Heye Buss
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - He Wang
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Yiming Xu
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Julian Maklar
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Frederic Joucken
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Lingkun Zeng
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Sebastian Stoll
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Chris Jozwiak
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - John Pepper
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Yi-De Chuang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jonathan D Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Zahid Hussain
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Alessandra Lanzara
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Robert A Kaindl
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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17
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Hedayat H, Bugini D, Karbassi S, Friedmann S, van Wezel J, Clark SR, Sayers C, Da Como E, Cerullo G, Dallera C, Carpene E. Charge-density-wave in 1T-TiSe2: exciton-phonon separation by femtosecond valence band dynamics. EPJ WEB OF CONFERENCES 2019. [DOI: 10.1051/epjconf/201920504008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the driving mechanism leading to charge-density-wave transition in 1T-TiSe2 single crystals. Our results show that both exciton instability and phonons cooperate to develop the charge ordered phase below 202 K.
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18
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Photo-induced semimetallic states realised in electron-hole coupled insulators. Nat Commun 2018; 9:4322. [PMID: 30333495 PMCID: PMC6192982 DOI: 10.1038/s41467-018-06801-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 09/14/2018] [Indexed: 11/08/2022] Open
Abstract
Using light to manipulate materials into desired states is one of the goals in condensed matter physics, since light control can provide ultrafast and environmentally friendly photonics devices. However, it is generally difficult to realise a photo-induced phase which is not merely a higher entropy phase corresponding to a high-temperature phase at equilibrium. Here, we report realisation of photo-induced insulator-to-metal transitions in Ta2Ni(Se1-xSx)5 including the excitonic insulator phase using time- and angle-resolved photoemission spectroscopy. From the dynamic properties of the system, we determine that screening of excitonic correlations plays a key role in the timescale of the transition to the metallic phase, which supports the existence of an excitonic insulator phase at equilibrium. The non-equilibrium metallic state observed unexpectedly in the direct-gap excitonic insulator opens up a new avenue to optical band engineering in electron-hole coupled systems.
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19
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Corder C, Zhao P, Bakalis J, Li X, Kershis MD, Muraca AR, White MG, Allison TK. Ultrafast extreme ultraviolet photoemission without space charge. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2018; 5:054301. [PMID: 30246049 PMCID: PMC6127013 DOI: 10.1063/1.5045578] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 08/16/2018] [Indexed: 05/27/2023]
Abstract
Time- and Angle-resolved photoelectron spectroscopy from surfaces can be used to record the dynamics of electrons and holes in condensed matter on ultrafast time scales. However, ultrafast photoemission experiments using extreme-ultraviolet (XUV) light have previously been limited by either space-charge effects, low photon flux, or limited tuning range. In this article, we describe XUV photoelectron spectroscopy experiments with up to 5 nA of average sample current using a tunable cavity-enhanced high-harmonic source operating at 88 MHz repetition rate. The source delivers >1011 photons/s in isolated harmonics to the sample over a broad photon energy range from 18 to 37 eV with a spot size of 58 × 100 μm2. From photoelectron spectroscopy data, we place conservative upper limits on the XUV pulse duration and photon energy bandwidth of 93 fs and 65 meV, respectively. The high photocurrent, lack of strong space charge distortions of the photoelectron spectra, and excellent isolation of individual harmonic orders allow us to observe laser-induced modifications of the photoelectron spectra at the 10-4 level, enabling time-resolved XUV photoemission experiments in a qualitatively new regime.
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Affiliation(s)
| | - Peng Zhao
- Stony Brook University, Stony Brook, New York 11794-3400, USA
| | - Jin Bakalis
- Stony Brook University, Stony Brook, New York 11794-3400, USA
| | - Xinlong Li
- Stony Brook University, Stony Brook, New York 11794-3400, USA
| | | | - Amanda R Muraca
- Stony Brook University, Stony Brook, New York 11794-3400, USA
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20
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Tian X, Wei R, Liu M, Zhu C, Luo Z, Wang F, Qiu J. Ultrafast saturable absorption in TiS 2 induced by non-equilibrium electrons and the generation of a femtosecond mode-locked laser. NANOSCALE 2018; 10:9608-9615. [PMID: 29749417 DOI: 10.1039/c8nr01573b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Non-equilibrium electrons induced by ultrafast laser excitation in a correlated electron material can disturb the Fermi energy as well as optical nonlinearity. Here, non-equilibrium electrons translate a semiconductor TiS2 material into a plasma to generate broad band nonlinear optical saturable absorption with a sub-picosecond recovery time of ∼768 fs (corresponding to modulation frequencies over 1.3 THz) and a modulation response up to ∼145%. Based on this optical nonlinear modulator, a stable femtosecond mode-locked pulse with a pulse duration of ∼402 fs and a pulse train with a period of ∼175.5 ns is observed in the all-optical system. The findings indicate that non-equilibrium electrons can promote a TiS2-based saturable absorber to be an ultrafast switch for a femtosecond pulse output.
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Affiliation(s)
- Xiangling Tian
- State Key Laboratory of Luminescent Materials and Devices and School of Materials Science and Engineering, South China University of Technology, Wushan Road 381, Guangzhou 510641, PR China
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21
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Eich S, Plötzing M, Rollinger M, Emmerich S, Adam R, Chen C, Kapteyn HC, Murnane MM, Plucinski L, Steil D, Stadtmüller B, Cinchetti M, Aeschlimann M, Schneider CM, Mathias S. Band structure evolution during the ultrafast ferromagnetic-paramagnetic phase transition in cobalt. SCIENCE ADVANCES 2017; 3:e1602094. [PMID: 28378016 PMCID: PMC5365247 DOI: 10.1126/sciadv.1602094] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 02/09/2017] [Indexed: 05/29/2023]
Abstract
The evolution of the electronic band structure of the simple ferromagnets Fe, Co, and Ni during their well-known ferromagnetic-paramagnetic phase transition has been under debate for decades, with no clear and even contradicting experimental observations so far. Using time- and spin-resolved photoelectron spectroscopy, we can make a movie on how the electronic properties change in real time after excitation with an ultrashort laser pulse. This allows us to monitor large transient changes in the spin-resolved electronic band structure of cobalt for the first time. We show that the loss of magnetization is not only found around the Fermi level, where the states are affected by the laser excitation, but also reaches much deeper into the electronic bands. We find that the ferromagnetic-paramagnetic phase transition cannot be explained by a loss of the exchange splitting of the spin-polarized bands but instead shows rapid band mirroring after the excitation, which is a clear signature of extremely efficient ultrafast magnon generation. Our result helps to understand band structure formation in these seemingly simple ferromagnetic systems and gives first clear evidence of the transient processes relevant to femtosecond demagnetization.
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Affiliation(s)
- Steffen Eich
- University of Kaiserslautern and Research Center OPTIMAS, 67663 Kaiserslautern, Germany
| | - Moritz Plötzing
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI 6), 52425 Jülich, Germany
- Experimentalphysik Universität Duisburg-Essen, Lotharstraße 1, 47057 Duisburg,Germany
| | - Markus Rollinger
- University of Kaiserslautern and Research Center OPTIMAS, 67663 Kaiserslautern, Germany
| | - Sebastian Emmerich
- University of Kaiserslautern and Research Center OPTIMAS, 67663 Kaiserslautern, Germany
- Graduate School MAINZ, Gottlieb-Daimler-Strasse 47, 67663 Kaiserslautern, Germany
| | - Roman Adam
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI 6), 52425 Jülich, Germany
| | - Cong Chen
- JILA, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309–0440, USA
| | - Henry Cornelius Kapteyn
- JILA, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309–0440, USA
| | - Margaret M. Murnane
- JILA, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309–0440, USA
| | - Lukasz Plucinski
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI 6), 52425 Jülich, Germany
- Experimentalphysik Universität Duisburg-Essen, Lotharstraße 1, 47057 Duisburg,Germany
| | - Daniel Steil
- Georg-August-Universität Göttingen, I. Physikalisches Institut, 37077 Göttingen, Germany
| | - Benjamin Stadtmüller
- University of Kaiserslautern and Research Center OPTIMAS, 67663 Kaiserslautern, Germany
- Graduate School MAINZ, Gottlieb-Daimler-Strasse 47, 67663 Kaiserslautern, Germany
| | - Mirko Cinchetti
- Experimentelle Physik VI, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - Martin Aeschlimann
- University of Kaiserslautern and Research Center OPTIMAS, 67663 Kaiserslautern, Germany
| | - Claus M. Schneider
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI 6), 52425 Jülich, Germany
- Experimentalphysik Universität Duisburg-Essen, Lotharstraße 1, 47057 Duisburg,Germany
| | - Stefan Mathias
- Georg-August-Universität Göttingen, I. Physikalisches Institut, 37077 Göttingen, Germany
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