1
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Reinhard M, Kunnus K, Ledbetter K, Biasin E, Zederkof DB, Alonso-Mori R, van Driel TB, Nelson S, Kozina M, Borkiewicz OJ, Lorenc M, Cammarata M, Collet E, Sokaras D, Cordones AA, Gaffney KJ. Observation of a Picosecond Light-Induced Spin Transition in Polymeric Nanorods. ACS NANO 2024. [PMID: 38833689 DOI: 10.1021/acsnano.3c10042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
Spin transition (ST) materials are attractive for developing photoswitchable devices, but their slow material transformations limit device applications. Size reduction could enable faster switching, but the photoinduced dynamics at the nanoscale remains poorly understood. Here, we report a femtosecond optical pump multimodal X-ray probe study of polymeric nanorods. Simultaneously tracking the ST order parameter with X-ray emission spectroscopy and structure with X-ray diffraction, we observe photodoping of the low-spin-lattice within ∼150 fs. Above a ∼16% photodoping threshold, the transition to the high-spin phase occurs following an incubation period assigned to vibrational energy redistribution within the nanorods activating the molecular spin switching. Above ∼60% photodoping, the incubation period disappears, and the transition completes within ∼50 ps, preceded by the elastic nanorod expansion in response to the photodoping. These results support the feasibility of ST material-based GHz optical switching applications.
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Affiliation(s)
- Marco Reinhard
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Kristjan Kunnus
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Kathryn Ledbetter
- Department of Physics, Stanford University, Stanford, California 94305, United States
| | - Elisa Biasin
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | | | - Roberto Alonso-Mori
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Tim Brandt van Driel
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Silke Nelson
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Michael Kozina
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Olaf J Borkiewicz
- X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Maciej Lorenc
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes)─UMR 6251, 35000 Rennes, France
| | - Marco Cammarata
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes)─UMR 6251, 35000 Rennes, France
| | - Eric Collet
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes)─UMR 6251, 35000 Rennes, France
| | - Dimosthenis Sokaras
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Amy A Cordones
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Kelly J Gaffney
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
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2
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Lee SY, Seo HK, Jeong SY, Yang MK. Improved Electrical Characteristics of Field Effect Transistors with GeSeTe-Based Ovonic Threshold Switching Devices. MATERIALS (BASEL, SWITZERLAND) 2023; 16:4315. [PMID: 37374499 DOI: 10.3390/ma16124315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/05/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023]
Abstract
Hyper-field effect transistors (hyper-FETs) are crucial in the development of low-power logic devices. With the increasing significance of power consumption and energy efficiency, conventional logic devices can no longer achieve the required performance and low-power operation. Next-generation logic devices are designed based on complementary metal-oxide-semiconductor circuits, and the subthreshold swing of existing metal-oxide semiconductor field effect transistors (MOSFETs) cannot be reduced below 60 mV/dec at room temperature owing to the thermionic carrier injection mechanism in the source region. Therefore, new devices must be developed to overcome these limitations. In this study, we present a novel threshold switch (TS) material, which can be applied to logic devices by employing ovonic threshold switch (OTS) materials, failure control of insulator-metal transition materials, and structural optimization. The proposed TS material is connected to a FET device to evaluate its performance. The results demonstrate that commercial transistors connected in series with GeSeTe-based OTS devices exhibit significantly lower subthreshold swing values, high on/off current ratios, and high durability of up to 108.
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Affiliation(s)
- Su Yeon Lee
- Artificial Intelligence Convergence Research Laboratory, Sahmyook University, Seoul 01795, Republic of Korea
| | - Hyun Kyu Seo
- Artificial Intelligence Convergence Research Laboratory, Sahmyook University, Seoul 01795, Republic of Korea
| | - Se Yeon Jeong
- Artificial Intelligence Convergence Research Laboratory, Sahmyook University, Seoul 01795, Republic of Korea
| | - Min Kyu Yang
- Artificial Intelligence Convergence Research Laboratory, Sahmyook University, Seoul 01795, Republic of Korea
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3
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Qaderi F, Rosca T, Burla M, Leuthold J, Flandre D, Ionescu AM. Millimeter-wave to near-terahertz sensors based on reversible insulator-to-metal transition in VO 2. COMMUNICATIONS MATERIALS 2023; 4:34. [PMID: 38665394 PMCID: PMC11041681 DOI: 10.1038/s43246-023-00350-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 03/21/2023] [Indexed: 04/28/2024]
Abstract
In the quest for low power bio-inspired spiking sensors, functional oxides like vanadium dioxide are expected to enable future energy efficient sensing. Here, we report uncooled millimeter-wave spiking detectors based on the sensitivity of insulator-to-metal transition threshold voltage to the incident wave. The detection concept is demonstrated through actuation of biased VO2 switches encapsulated in a pair of coupled antennas by interrupting coplanar waveguides for broadband measurements, on silicon substrates. Ultimately, we propose an electromagnetic-wave-sensitive voltage-controlled spike generator based on VO2 switches in an astable spiking circuit. The fabricated sensors show responsivities of around 66.3 MHz.W-1 at 1 μW, with a low noise equivalent power of 5 nW.Hz-0.5 at room temperature, for a footprint of 2.5 × 10-5 mm2. The responsivity in static characterizations is 76 kV.W-1. Based on experimental statistical data measured on robust fabricated devices, we discuss stochastic behavior and noise limits of VO2 -based spiking sensors applicable for wave power sensing in mm-wave and sub-terahertz range.
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Affiliation(s)
- Fatemeh Qaderi
- Nanoelectronic devices laboratory (Nanolab), Department of Electrical Engineering, École polytechnique fédérale de Lausanne (EPFL), EPFL STI IEL NANOLAB, ELB 335, Station 11, Lausanne, 1015 Switzerland
| | - Teodor Rosca
- Nanoelectronic devices laboratory (Nanolab), Department of Electrical Engineering, École polytechnique fédérale de Lausanne (EPFL), EPFL STI IEL NANOLAB, ELB 335, Station 11, Lausanne, 1015 Switzerland
| | - Maurizio Burla
- Institute of Electromagnetic Fields (IEF), Eidgenössische Technische Hochschule Zürich (ETHZ), ETZ K 82, Gloriastrasse 35, Zürich, 8092 Switzerland
| | - Juerg Leuthold
- Institute of Electromagnetic Fields (IEF), Eidgenössische Technische Hochschule Zürich (ETHZ), ETZ K 82, Gloriastrasse 35, Zürich, 8092 Switzerland
| | - Denis Flandre
- ICTEAM, Ecole Polytechnique de Louvain (UCLouvain), ELEN, Place du Levant 3/L5.03.02, Louvain-la-Neuve, 1348 Belgium
| | - Adrian M. Ionescu
- Nanoelectronic devices laboratory (Nanolab), Department of Electrical Engineering, École polytechnique fédérale de Lausanne (EPFL), EPFL STI IEL NANOLAB, ELB 335, Station 11, Lausanne, 1015 Switzerland
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4
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Transient dynamics of the phase transition in VO 2 revealed by mega-electron-volt ultrafast electron diffraction. Nat Commun 2023; 14:1265. [PMID: 36882433 PMCID: PMC9992676 DOI: 10.1038/s41467-023-37000-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 02/20/2023] [Indexed: 03/09/2023] Open
Abstract
Vanadium dioxide (VO2) exhibits an insulator-to-metal transition accompanied by a structural transition near room temperature. This transition can be triggered by an ultrafast laser pulse. Exotic transient states, such as a metallic state without structural transition, were also proposed. These unique characteristics let VO2 have great potential in thermal switchable devices and photonic applications. Although great efforts have been made, the atomic pathway during the photoinduced phase transition is still not clear. Here, we synthesize freestanding quasi-single-crystal VO2 films and examine their photoinduced structural phase transition with mega-electron-volt ultrafast electron diffraction. Leveraging the high signal-to-noise ratio and high temporal resolution, we observe that the disappearance of vanadium dimers and zigzag chains does not coincide with the transformation of crystal symmetry. After photoexcitation, the initial structure is strongly modified within 200 femtoseconds, resulting in a transient monoclinic structure without vanadium dimers and zigzag chains. Then, it continues to evolve to the final tetragonal structure in approximately 5 picoseconds. In addition, only one laser fluence threshold instead of two thresholds suggested in polycrystalline samples is observed in our quasi-single-crystal samples. Our findings provide essential information for a comprehensive understanding of the photoinduced ultrafast phase transition in VO2.
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5
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Kim YJ, Nho HW, Ji S, Lee H, Ko H, Weissenrieder J, Kwon OH. Femtosecond-resolved imaging of a single-particle phase transition in energy-filtered ultrafast electron microscopy. SCIENCE ADVANCES 2023; 9:eadd5375. [PMID: 36706188 PMCID: PMC9882981 DOI: 10.1126/sciadv.add5375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 12/20/2022] [Indexed: 06/18/2023]
Abstract
Using an energy filter in transmission electron microscopy has enabled elemental mapping at the atomic scale and improved the precision of structural determination by gating inelastic and elastic imaging electrons, respectively. Here, we use an energy filter in ultrafast electron microscopy to enhance the temporal resolution toward the domain of atomic motion. Visualizing transient structures with femtosecond temporal precision was achieved by selecting imaging electrons in a narrow energy distribution from dense chirped photoelectron packets with broad longitudinal momentum distributions and thus typically exhibiting picosecond durations. In this study, the heterogeneous ultrafast phase transitions of vanadium dioxide (VO2) nanoparticles, a representative strongly correlated system, were filmed and attributed to the emergence of a transient, low-symmetry metallic phase caused by different local strains. Our approach enables electron microscopy to access the time scale of elementary nuclear motion to visualize the onset of the structural dynamics of matter at the nanoscale.
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Affiliation(s)
- Ye-Jin Kim
- Department of Chemistry, College of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea
- Center for Soft and Living Matter, Institute for Basic Science, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Hak-Won Nho
- Department of Chemistry, College of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea
- Center for Soft and Living Matter, Institute for Basic Science, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Shaozheng Ji
- Materials and Nano Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
| | - Hyejin Lee
- School of Energy and Chemical Engineering, UNIST, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Hyunhyub Ko
- School of Energy and Chemical Engineering, UNIST, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Jonas Weissenrieder
- Materials and Nano Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
| | - Oh-Hoon Kwon
- Department of Chemistry, College of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea
- Center for Soft and Living Matter, Institute for Basic Science, 50 UNIST-gil, Ulsan 44919, Republic of Korea
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6
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Pivotal role of reversible NiO 6 geometric conversion in oxygen evolution. Nature 2022; 611:702-708. [PMID: 36289339 DOI: 10.1038/s41586-022-05296-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/31/2022] [Indexed: 01/20/2023]
Abstract
Realizing an efficient electron transfer process in the oxygen evolution reaction by modifying the electronic states around the Fermi level is crucial in developing high-performing and robust electrocatalysts1-3. Typically, electron transfer proceeds solely through either a metal redox chemistry (an adsorbate evolution mechanism (AEM), with metal bands around the Fermi level) or an oxygen redox chemistry (a lattice oxygen oxidation mechanism (LOM), with oxygen bands around the Fermi level), without the concurrent occurrence of both metal and oxygen redox chemistries in the same electron transfer pathway1-15. Here we report an electron transfer mechanism that involves a switchable metal and oxygen redox chemistry in nickel-oxyhydroxide-based materials with light as the trigger. In contrast to the traditional AEM and LOM, the proposed light-triggered coupled oxygen evolution mechanism requires the unit cell to undergo reversible geometric conversion between octahedron (NiO6) and square planar (NiO4) to achieve electronic states (around the Fermi level) with alternative metal and oxygen characters throughout the oxygen evolution process. Utilizing this electron transfer pathway can bypass the potential limiting steps, that is, oxygen-oxygen bonding in AEM and deprotonation in LOM1-5,8. As a result, the electrocatalysts that operate through this route show superior activity compared with previously reported electrocatalysts. Thus, it is expected that the proposed light-triggered coupled oxygen evolution mechanism adds a layer of understanding to the oxygen evolution research scene.
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7
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Abstract
Photoinduced phase transition (PIPT) is always treated as a coherent process, but ultrafast disordering in PIPT is observed in recent experiments. Utilizing the real-time time-dependent density functional theory method, here we track the motion of individual vanadium (V) ions during PIPT in VO2 and uncover that their coherent or disordered dynamics can be manipulated by tuning the laser fluence. We find that the photoexcited holes generate a force on each V-V dimer to drive their collective coherent motion, in competing with the thermal-induced vibrations. If the laser fluence is so weak that the photoexcited hole density is too low to drive the phase transition alone, the PIPT is a disordered process due to the interference of thermal phonons. We also reveal that the photoexcited holes populated by the V-V dimerized bonding states will become saturated if the laser fluence is too strong, limiting the timescale of photoinduced phase transition.
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8
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Sood A, Shen X, Shi Y, Kumar S, Park SJ, Zajac M, Sun Y, Chen LQ, Ramanathan S, Wang X, Chueh WC, Lindenberg AM. Universal phase dynamics in VO 2 switches revealed by ultrafast operando diffraction. Science 2021; 373:352-355. [PMID: 34437156 DOI: 10.1126/science.abc0652] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/07/2021] [Indexed: 11/02/2022]
Abstract
Understanding the pathways and time scales underlying electrically driven insulator-metal transitions is crucial for uncovering the fundamental limits of device operation. Using stroboscopic electron diffraction, we perform synchronized time-resolved measurements of atomic motions and electronic transport in operating vanadium dioxide (VO2) switches. We discover an electrically triggered, isostructural state that forms transiently on microsecond time scales, which is shown by phase-field simulations to be stabilized by local heterogeneities and interfacial interactions between the equilibrium phases. This metastable phase is similar to that formed under photoexcitation within picoseconds, suggesting a universal transformation pathway. Our results establish electrical excitation as a route for uncovering nonequilibrium and metastable phases in correlated materials, opening avenues for engineering dynamical behavior in nanoelectronics.
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Affiliation(s)
- Aditya Sood
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA. .,Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Xiaozhe Shen
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Yin Shi
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Suhas Kumar
- Hewlett Packard Labs, Palo Alto, CA 94304, USA
| | - Su Ji Park
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Marc Zajac
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Yifei Sun
- School of Materials Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Long-Qing Chen
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Shriram Ramanathan
- School of Materials Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Xijie Wang
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - William C Chueh
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.,Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Aaron M Lindenberg
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA. .,Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.,SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
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9
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Nanoscale-femtosecond dielectric response of Mott insulators captured by two-color near-field ultrafast electron microscopy. Nat Commun 2020; 11:5770. [PMID: 33188192 PMCID: PMC7666229 DOI: 10.1038/s41467-020-19636-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 10/26/2020] [Indexed: 11/09/2022] Open
Abstract
Characterizing and controlling the out-of-equilibrium state of nanostructured Mott insulators hold great promises for emerging quantum technologies while providing an exciting playground for investigating fundamental physics of strongly-correlated systems. Here, we use two-color near-field ultrafast electron microscopy to photo-induce the insulator-to-metal transition in a single VO2 nanowire and probe the ensuing electronic dynamics with combined nanometer-femtosecond resolution (10−21 m ∙ s). We take advantage of a femtosecond temporal gating of the electron pulse mediated by an infrared laser pulse, and exploit the sensitivity of inelastic electron-light scattering to changes in the material dielectric function. By spatially mapping the near-field dynamics of an individual nanowire of VO2, we observe that ultrafast photo-doping drives the system into a metallic state on a timescale of ~150 fs without yet perturbing the crystalline lattice. Due to the high versatility and sensitivity of the electron probe, our method would allow capturing the electronic dynamics of a wide range of nanoscale materials with ultimate spatiotemporal resolution. The fs control of an insulator-to-metal transition down to a few nanometers and its real-time/real space observation remain a challenge. Here, the authors demonstrate a method based on ultrafast electron microscopy to provide a nm/fs resolved view of the electronic dynamics in a single VO2 nanowire.
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10
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Li W, Naik GV. Large Optical Tunability from Charge Density Waves in 1T-TaS 2 under Incoherent Illumination. NANO LETTERS 2020; 20:7868-7873. [PMID: 32816498 DOI: 10.1021/acs.nanolett.0c02234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Strongly correlated materials possess a complex energy landscape and host many interesting physical phenomena, including charge density waves (CDWs). CDWs have been observed and extensively studied in many materials since their first discovery in 1972. Yet they present ample opportunities for discovery. Here, we report a large tunability in the optical response of a quasi-2D CDW material, 1T-TaS2, upon incoherent light illumination at room temperature. We hypothesize that the observed tunability is a consequence of light-induced rearrangement of CDW stacking across the layers of 1T-TaS2. Our model, based on this hypothesis, agrees reasonably well with experiments suggesting that the interdomain CDW interaction is a vital potentially knob to control the phase of strongly correlated materials.
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Affiliation(s)
- Weijian Li
- Applied Physics Graduate Program, Smalley-Curl Institute, Rice University, Houston, Texas 77005, United States
| | - Gururaj V Naik
- Electrical & Computer Engineering, Rice University, Houston, Texas 77005, United States
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11
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Non-thermal resistive switching in Mott insulator nanowires. Nat Commun 2020; 11:2985. [PMID: 32532988 PMCID: PMC7293290 DOI: 10.1038/s41467-020-16752-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 05/20/2020] [Indexed: 11/26/2022] Open
Abstract
Resistive switching can be achieved in a Mott insulator by applying current/voltage, which triggers an insulator-metal transition (IMT). This phenomenon is key for understanding IMT physics and developing novel memory elements and brain-inspired technology. Despite this, the roles of electric field and Joule heating in the switching process remain controversial. Using nanowires of two archetypal Mott insulators—VO2 and V2O3 we unequivocally show that a purely non-thermal electrical IMT can occur in both materials. The mechanism behind this effect is identified as field-assisted carrier generation leading to a doping driven IMT. This effect can be controlled by similar means in both VO2 and V2O3, suggesting that the proposed mechanism is generally applicable to Mott insulators. The energy consumption associated with the non-thermal IMT is extremely low, rivaling that of state-of-the-art electronics and biological neurons. These findings pave the way towards highly energy-efficient applications of Mott insulators. Despite intensive research on the electrically driven insulator-to-metal transition, this phenomenon is not well understood. Using quasi 1D nanowires of two Mott insulators, the authors reveal the central role of defects in enabling a non-thermal doping driven insulator-to metal transition.
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12
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Mogunov IA, Lysenko S, Fedianin AE, Fernández FE, Rúa A, Kent AJ, Akimov AV, Kalashnikova AM. Large non-thermal contribution to picosecond strain pulse generation using the photo-induced phase transition in VO 2. Nat Commun 2020; 11:1690. [PMID: 32245951 PMCID: PMC7125085 DOI: 10.1038/s41467-020-15372-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 03/05/2020] [Indexed: 11/10/2022] Open
Abstract
Picosecond strain pulses are a versatile tool for investigation of mechanical properties of meso- and nano-scale objects with high temporal and spatial resolutions. Generation of such pulses is traditionally realized via ultrafast laser excitation of a light-to-strain transducer involving thermoelastic, deformation potential, or inverse piezoelectric effects. These approaches unavoidably lead to heat dissipation and a temperature rise, which can modify delicate specimens, like biological tissues, and ultimately destroy the transducer itself limiting the amplitude of generated picosecond strain. Here we propose a non-thermal mechanism for generating picosecond strain pulses via ultrafast photo-induced first-order phase transitions (PIPTs). We perform experiments on vanadium dioxide VO2 films, which exhibit a first-order PIPT accompanied by a lattice change. We demonstrate that during femtosecond optical excitation of VO2 the PIPT alone contributes to ultrafast expansion of this material as large as 0.45%, which is not accompanied by heat dissipation, and, for excitation density of 8 mJ cm−2, exceeds the contribution from thermoelastic effect by a factor of five. Ultrafast driving of vanadium dioxide can induce a large structural phase transition, which can be used to generate picosecond strain pulses. Here the authors show that the photo-induced phase transition can contribute 0.45% strain without causing undesirable heating.
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Affiliation(s)
| | - Sergiy Lysenko
- Department of Physics, University of Puerto Rico, Mayaguez, PR, 00681, USA
| | | | - Félix E Fernández
- Department of Physics, University of Puerto Rico, Mayaguez, PR, 00681, USA
| | - Armando Rúa
- Department of Physics, University of Puerto Rico, Mayaguez, PR, 00681, USA
| | - Anthony J Kent
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Andrey V Akimov
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
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13
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Stoica VA, Laanait N, Dai C, Hong Z, Yuan Y, Zhang Z, Lei S, McCarter MR, Yadav A, Damodaran AR, Das S, Stone GA, Karapetrova J, Walko DA, Zhang X, Martin LW, Ramesh R, Chen LQ, Wen H, Gopalan V, Freeland JW. Optical creation of a supercrystal with three-dimensional nanoscale periodicity. NATURE MATERIALS 2019; 18:377-383. [PMID: 30886403 DOI: 10.1038/s41563-019-0311-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 02/04/2019] [Indexed: 06/09/2023]
Abstract
Stimulation with ultrafast light pulses can realize and manipulate states of matter with emergent structural, electronic and magnetic phenomena. However, these non-equilibrium phases are often transient and the challenge is to stabilize them as persistent states. Here, we show that atomic-scale PbTiO3/SrTiO3 superlattices, counterpoising strain and polarization states in alternate layers, are converted by sub-picosecond optical pulses to a supercrystal phase. This phase persists indefinitely under ambient conditions, has not been created via equilibrium routes, and can be erased by heating. X-ray scattering and microscopy show this unusual phase consists of a coherent three-dimensional structure with polar, strain and charge-ordering periodicities of up to 30 nm. By adjusting only dielectric properties, the phase-field model describes this emergent phase as a photo-induced charge-stabilized supercrystal formed from a two-phase equilibrium state. Our results demonstrate opportunities for light-activated pathways to thermally inaccessible and emergent metastable states.
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Affiliation(s)
- V A Stoica
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA
| | - N Laanait
- Center for Nanophase Materials Sciences, Oak Ridge, TN, USA
| | - C Dai
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA
| | - Z Hong
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA
| | - Y Yuan
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA
| | - Z Zhang
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - S Lei
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA
| | - M R McCarter
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - A Yadav
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - A R Damodaran
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - S Das
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - G A Stone
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA
| | - J Karapetrova
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - D A Walko
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - X Zhang
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - L W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - R Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - L-Q Chen
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA
| | - H Wen
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - V Gopalan
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA.
| | - J W Freeland
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA.
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14
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Otto MR, René de Cotret LP, Valverde-Chavez DA, Tiwari KL, Émond N, Chaker M, Cooke DG, Siwick BJ. How optical excitation controls the structure and properties of vanadium dioxide. Proc Natl Acad Sci U S A 2019; 116:450-455. [PMID: 30587594 PMCID: PMC6329972 DOI: 10.1073/pnas.1808414115] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We combine ultrafast electron diffraction and time-resolved terahertz spectroscopy measurements to link structure and electronic transport properties during the photoinduced insulator-metal transitions in vanadium dioxide. We determine the structure of the metastable monoclinic metal phase, which exhibits antiferroelectric charge order arising from a thermally activated, orbital-selective phase transition in the electron system. The relative contribution of the photoinduced monoclinic and rutile metals to the time-dependent and pump-fluence-dependent multiphase character of the film is established, as is the respective impact of these two distinct phase transitions on the observed changes in terahertz conductivity. Our results represent an important example of how light can control the properties of strongly correlated materials and demonstrate that multimodal experiments are essential when seeking a detailed connection between ultrafast changes in optical-electronic properties and lattice structure.
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Affiliation(s)
- Martin R Otto
- Department of Physics, Center for the Physics of Materials, McGill University, Montreal, QC, Canada H3A 2T8;
| | - Laurent P René de Cotret
- Department of Physics, Center for the Physics of Materials, McGill University, Montreal, QC, Canada H3A 2T8
| | - David A Valverde-Chavez
- Department of Physics, Center for the Physics of Materials, McGill University, Montreal, QC, Canada H3A 2T8
| | - Kunal L Tiwari
- Department of Physics, Center for the Physics of Materials, McGill University, Montreal, QC, Canada H3A 2T8
| | - Nicolas Émond
- Institut National de la Recherche Scientifique, Centre Énergie Matériaux et Télécommunications, Université du Québec, Varennes, QC, Canada J3X 1S2
| | - Mohamed Chaker
- Institut National de la Recherche Scientifique, Centre Énergie Matériaux et Télécommunications, Université du Québec, Varennes, QC, Canada J3X 1S2
| | - David G Cooke
- Department of Physics, Center for the Physics of Materials, McGill University, Montreal, QC, Canada H3A 2T8
| | - Bradley J Siwick
- Department of Physics, Center for the Physics of Materials, McGill University, Montreal, QC, Canada H3A 2T8
- Department of Chemistry, McGill University, Montreal, QC, Canada H3A 0B8
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15
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Pontius N, Beye M, Trabant C, Mitzner R, Sorgenfrei F, Kachel T, Wöstmann M, Roling S, Zacharias H, Ivanov R, Treusch R, Buchholz M, Metcalf P, Schüßler-Langeheine C, Föhlisch A. Probing the non-equilibrium transient state in magnetite by a jitter-free two-color X-ray pump and X-ray probe experiment. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2018; 5:054501. [PMID: 30310825 PMCID: PMC6158032 DOI: 10.1063/1.5042847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 08/23/2018] [Indexed: 06/08/2023]
Abstract
We present a general experimental concept for jitter-free pump and probe experiments at free electron lasers. By generating pump and probe pulse from one and the same X-ray pulse using an optical split-and-delay unit, we obtain a temporal resolution that is limited only by the X-ray pulse lengths. In a two-color X-ray pump and X-ray probe experiment with sub 70 fs temporal resolution, we selectively probe the response of orbital and charge degree of freedom in the prototypical functional oxide magnetite after photoexcitation. We find electronic order to be quenched on a time scale of (30 ± 30) fs and hence most likely faster than what is to be expected for any lattice dynamics. Our experimental result hints to the formation of a short lived transient state with decoupled electronic and lattice degree of freedom in magnetite. The excitation and relaxation mechanism for X-ray pumping is discussed within a simple model leading to the conclusion that within the first 10 fs the original photoexcitation decays into low-energy electronic excitations comparable to what is achieved by optical pump pulse excitation. Our findings show on which time scales dynamical decoupling of degrees of freedom in functional oxides can be expected and how to probe this selectively with soft X-ray pulses. Results can be expected to provide crucial information for theories for ultrafast behavior of materials and help to develop concepts for novel switching devices.
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Affiliation(s)
- N Pontius
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - M Beye
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - C Trabant
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - R Mitzner
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - F Sorgenfrei
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - T Kachel
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - M Wöstmann
- WWU Münster, Physikalisches Institut, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
| | - S Roling
- WWU Münster, Physikalisches Institut, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
| | - H Zacharias
- WWU Münster, Physikalisches Institut, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
| | - R Ivanov
- Deutsches Elektronen-Synchrotron, Notkestr. 85, 22607 Hamburg, Germany
| | - R Treusch
- Deutsches Elektronen-Synchrotron, Notkestr. 85, 22607 Hamburg, Germany
| | - M Buchholz
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
| | - P Metcalf
- School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, USA
| | - C Schüßler-Langeheine
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - A Föhlisch
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
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16
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Wang Y, Sun X, Chen Z, Cai Z, Zhou H, Lu TM, Shi J. Defect-engineered epitaxial VO 2±δ in strain engineering of heterogeneous soft crystals. SCIENCE ADVANCES 2018; 4:eaar3679. [PMID: 29806024 PMCID: PMC5969812 DOI: 10.1126/sciadv.aar3679] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 04/17/2018] [Indexed: 05/16/2023]
Abstract
The success of strain engineering has made a step further for the enhancement of material properties and the introduction of new physics, especially with the discovery of the critical roles of strain in the heterogeneous interface between two dissimilar materials (for example, FeSe/SrTiO3). On the other hand, the strain manipulation has been limited to chemical epitaxy and nanocomposites that, to a large extent, limit the possible material systems that can be explored. By defect engineering, we obtained, for the first time, dense three-dimensional strongly correlated VO2±δ epitaxial nanoforest arrays that can be used as a novel "substrate" for dynamic strain engineering, due to its metal-insulator transition. The highly dense nanoforest is promising for the possible realization of bulk strain similar to the effect of nanocomposites. By growing single-crystalline halide perovskite CsPbBr3, a mechanically soft and emerging semiconducting material, onto the VO2±δ, a heterogeneous interface is created that can entail a ~1% strain transfer upon the metal-insulator transition of VO2±δ. This strain is large enough to trigger a structural phase transition featured by PbX6 octahedral tilting along with a modification of the photoluminescence energy landscape in halide perovskite. Our findings suggest a promising strategy of dynamic strain engineering in a heterogeneous interface carrying soft and strain-sensitive semiconductors that can happen at a larger volumetric value surpassing the conventional critical thickness limit.
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Affiliation(s)
- Yiping Wang
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Xin Sun
- Department of Physics, Applied Physics, and Astronomy Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Zhizhong Chen
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Zhonghou Cai
- X-ray Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Hua Zhou
- X-ray Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Toh-Ming Lu
- Department of Physics, Applied Physics, and Astronomy Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Jian Shi
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
- Corresponding author.
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17
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Hwang IH, Jin Z, Park CI, Han SW. The influence of structural disorder and phonon on metal-to-insulator transition of VO 2. Sci Rep 2017; 7:14802. [PMID: 29093503 PMCID: PMC5666023 DOI: 10.1038/s41598-017-14235-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 10/06/2017] [Indexed: 11/09/2022] Open
Abstract
We used temperature-dependent x-ray absorption fine structure (XAFS) measurements to examine the local structural properties around vanadium atoms at the V K edge from VO2 films. A direct comparison of the simultaneously-measured resistance and XAFS regarding the VO2 films showed that the thermally-driven structural transition occurred prior to the resistance transition during a heating, while this change simultaneously occured during a cooling. Extended-XAFS (EXAFS) analysis revealed significant increases of the Debye-Waller factors of the V-O and V-V pairs in the {111} direction of the R-phase VO2 that are due to the phonons of the V-V arrays along the same direction in a metallic phase. The existance of a substantial amount of structural disorder on the V-V pairs along the c-axis in both M1 and R phases indicates the structural instability of V-V arrays in the axis. The anomalous structural disorder that was observed on all atomic sites at the structural phase transition prevents the migration of the V 3d1 electrons, resulting in a Mott insulator in the M2-phase VO2.
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Affiliation(s)
- In-Hui Hwang
- Department of Physics Education and Institute of Fusion Science, Jeonbuk(Chonbuk) National University, Jeonju, 54896, Korea
| | - Zhenlan Jin
- Department of Physics Education and Institute of Fusion Science, Jeonbuk(Chonbuk) National University, Jeonju, 54896, Korea
| | - Chang-In Park
- Department of Physics Education and Institute of Fusion Science, Jeonbuk(Chonbuk) National University, Jeonju, 54896, Korea
| | - Sang-Wook Han
- Department of Physics Education and Institute of Fusion Science, Jeonbuk(Chonbuk) National University, Jeonju, 54896, Korea.
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18
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Zhou F, Williams J, Ruan CY. Femtosecond electron spectroscopy in an electron microscope with high brightness beams. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.03.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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19
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Photoinduced Strain Release and Phase Transition Dynamics of Solid-Supported Ultrathin Vanadium Dioxide. Sci Rep 2017; 7:10045. [PMID: 28855670 PMCID: PMC5577108 DOI: 10.1038/s41598-017-10217-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 08/04/2017] [Indexed: 11/22/2022] Open
Abstract
The complex phase transitions of vanadium dioxide (VO2) have drawn continual attention for more than five decades. Dynamically, ultrafast electron diffraction (UED) with atomic-scale spatiotemporal resolution has been employed to study the reaction pathway in the photoinduced transition of VO2, using bulk and strain-free specimens. Here, we report the UED results from 10-nm-thick crystalline VO2 supported on Al2O3(0001) and examine the influence of surface stress on the photoinduced structural transformation. An ultrafast release of the compressive strain along the surface-normal direction is observed at early times following the photoexcitation, accompanied by faster motions of vanadium dimers that are more complex than simple dilation or bond tilting. Diffraction simulations indicate that the reaction intermediate involved on picosecond times may not be a single state, which implies non-concerted atomic motions on a multidimensional energy landscape. At longer times, a laser fluence multiple times higher than the thermodynamic enthalpy threshold is required for complete conversion from the initial monoclinic structure to the tetragonal lattice. For certain crystalline domains, the structural transformation is not seen even on nanosecond times following an intense photoexcitation. These results signify a time-dependent energy distribution among various degrees of freedom and reveal the nature of and the impact of strain on the photoinduced transition of VO2.
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20
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Choe HS, Suh J, Ko C, Dong K, Lee S, Park J, Lee Y, Wang K, Wu J. Enhancing Modulation of Thermal Conduction in Vanadium Dioxide Thin Film by Nanostructured Nanogaps. Sci Rep 2017; 7:7131. [PMID: 28769057 PMCID: PMC5540922 DOI: 10.1038/s41598-017-07466-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 06/23/2017] [Indexed: 11/09/2022] Open
Abstract
Efficient thermal management at the nanoscale is important for reducing energy consumption and dissipation in electronic devices, lab-on-a-chip platforms and energy harvest/conversion systems. For many of these applications, it is much desired to have a solid-state structure that reversibly switches thermal conduction with high ON/OFF ratios and at high speed. Here we describe design and implementation of a novel, all-solid-state thermal switching device by nanostructured phase transformation, i.e., modulation of contact pressure and area between two poly-silicon surfaces activated by microstructural change of a vanadium dioxide (VO2) thin film. Our solid-state devices demonstrate large and reversible alteration of cross-plane thermal conductance as a function of temperature, achieving a conductance ratio of at least 2.5. Our new approach using nanostructured phase transformation provides new opportunities for applications that require advanced temperature and heat regulations.
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Affiliation(s)
- Hwan Sung Choe
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Joonki Suh
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Changhyun Ko
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Kaichen Dong
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA.,Department of Precision Instrument, Tsinghua University, Beijing, 100084, China
| | - Sangwook Lee
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Joonsuk Park
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Yeonbae Lee
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Kevin Wang
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Junqiao Wu
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA. .,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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21
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Williams J, Zhou F, Sun T, Tao Z, Chang K, Makino K, Berz M, Duxbury PM, Ruan CY. Active control of bright electron beams with RF optics for femtosecond microscopy. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2017; 4:044035. [PMID: 28868325 PMCID: PMC5565489 DOI: 10.1063/1.4999456] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 08/08/2017] [Indexed: 06/07/2023]
Abstract
A frontier challenge in implementing femtosecond electron microscopy is to gain precise optical control of intense beams to mitigate collective space charge effects for significantly improving the throughput. Here, we explore the flexible uses of an RF cavity as a longitudinal lens in a high-intensity beam column for condensing the electron beams both temporally and spectrally, relevant to the design of ultrafast electron microscopy. Through the introduction of a novel atomic grating approach for characterization of electron bunch phase space and control optics, we elucidate the principles for predicting and controlling the phase space dynamics to reach optimal compressions at various electron densities and generating conditions. We provide strategies to identify high-brightness modes, achieving ∼100 fs and ∼1 eV resolutions with 106 electrons per bunch, and establish the scaling of performance for different bunch charges. These results benchmark the sensitivity and resolution from the fundamental beam brightness perspective and also validate the adaptive optics concept to enable delicate control of the density-dependent phase space structures to optimize the performance, including delivering ultrashort, monochromatic, high-dose, or coherent electron bunches.
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Affiliation(s)
- J Williams
- Department of Physics and Astronomy, East Lansing, Michigan 48824, USA
| | - F Zhou
- Department of Physics and Astronomy, East Lansing, Michigan 48824, USA
| | - T Sun
- Department of Physics and Astronomy, East Lansing, Michigan 48824, USA
| | - Z Tao
- Department of Physics and Astronomy, East Lansing, Michigan 48824, USA
| | - K Chang
- Department of Physics and Astronomy, East Lansing, Michigan 48824, USA
| | - K Makino
- Department of Physics and Astronomy, East Lansing, Michigan 48824, USA
| | - M Berz
- Department of Physics and Astronomy, East Lansing, Michigan 48824, USA
| | - P M Duxbury
- Department of Physics and Astronomy, East Lansing, Michigan 48824, USA
| | - C-Y Ruan
- Department of Physics and Astronomy, East Lansing, Michigan 48824, USA
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