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Applied physics Letters 2017年第9期110卷

作者： Bergeron, Hadallia Sangwan, Vinod K. McMorrow, Julian J. Campbell, Gavin P. Balla, Itamar Liu, Xiaolong Bedzyk, Michael J. Marks, Tobin J. Hersam, Mark C. Department of Materials Science and Engineering Northwestern University EvanstonIllinois60208 United States Applied Physics Graduate Program Northwestern University EvanstonIllinois60208 United States Department of Physics and Astronomy Northwestern University EvanstonIllinois60208 United States Department of Chemistry Northwestern University EvanstonIllinois60208 United States Department of Electrical Engineering and Computer Science Northwestern University EvanstonIllinois60208 United States

This article was originally published online on 30 January 2017. Due to a production error, outdated versions of Figures 1 and 4 appeared in the article as orig

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Irregular oscillatory patterns in the early-time region of coherent phonon generation in silicon

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Physical Review B 2017年第12期96卷 125204-125204页

作者： Yohei Watanabe Ken-ichi Hino Muneaki Hase Nobuya Maeshima Doctoral Program in Materials Science Graduate School of Pure and Applied Sciences University of Tsukuba Tsukuba Ibaraki 305-8573 Japan Division of Materials Science Faculty of Pure and Applied Sciences University of Tsukuba Tsukuba 305-8573 Japan Center for Computational Sciences University of Tsukuba Tsukuba 305-8577 Japan Division of Applied Physics Faculty of Pure and Applied Sciences University of Tsukuba Tsukuba 305-8573 Japan

Coherent phonon (CP) generation in an undoped Si crystal is theoretically investigated to shed light on unexplored quantum-mechanical effects in the early-time region immediately after the irradiation of ultrashort laser pulses. We examine time signals attributed to an induced charge density of an ionic core, placing the focus on the effects of the Rabi frequency Ω0cv on the signals; this frequency corresponds to the peak electric-field of the pulse. It is found that at specific Ω0cv's, where the energy of plasmon caused by photoexcited carriers coincides with the longitudinal-optical phonon energy, the energetically resonant interaction between these two modes leads to striking anticrossings, revealing irregular oscillations with anomalously enhanced amplitudes in the observed time signals. Also, the oscillatory pattern is subject to the Rabi flopping of the excited carrier density that is controlled by Ω0cv. These findings show that the early-time region is enriched with quantum-mechanical effects inherent in the CP generation, though experimental signals are more or less masked by the so-called coherent artifact due to nonlinear optical effects.

关键词： Electron-phonon coupling Optical phonons Plasma oscillations Ultrafast phenomena Elemental semiconductors Optical absorption spectroscopy

Superconductivity and frozen electronic states at the (111) LaAlO3/SrTiO3 interface

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arXiv 2017年

作者： Davis, S. Huang, Z. Han, K. Ariando Venkatesan, T. Chandrasekhar, V. Graduate Program in Applied Physics Department of Physics and Astronomy Northwestern University 2145 Sheridan Road EvanstonIL60208 United States NUSNNI-Nanocore National University of Singapore 117411 Singapore Department of Physics National University of Singapore 117551 Singapore NUS Graduate School for Integrative Sciences & Engineering National University of Singapore 117456 Singapore NUSNNI-NanoCore National University of Singapore 117411 Singapore Department of Physics National University of Singapore 117542 Singapore Department of Electrical and Computer Engineering National University of Singapore 117576 Singapore Department of Material Science and Engineering National University of Singapore 117575 Singapore

In spite of Anderson’s theorem1, disorder is known to affect superconductivity in conventional s-wave superconductors2–11. In most superconductors, the degree of disorder is fixed during sample preparation. Here we report measurements of the superconducting properties of the two-dimensional gas that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) in the (111) crystal orientation, a system that permits in situ tuning of carrier density and disorder by means of a back gate voltage Vg. Like the (001) oriented LAO/STO interface12–15, superconductivity at the (111) LAO/STO interface can be tuned by Vg. In contrast to the (001) interface, superconductivity in these (111) samples is anisotropic, being different along different interface crystal directions, consistent with the strong anisotropy already observed other transport properties at the (111) LAO/STO interface16,17. In addition, we find that the (111) interface samples "remember" the backgate voltage VF at which they are cooled at temperatures near the superconducting transition temperature Tc, even if Vg is subsequently changed at lower temperatures. The low energy scale and other characteristics of this memory effect ( Copyright © 2017, The Authors. All rights reserved.

关键词： Aluminum compounds

Radial acceleration relation between baryons and dark or phantom matter in the super-critical acceleration regime of nearly spherical galaxies

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arXiv 2017年

作者： Chae, Kyu-Hyun Bernardi, Mariangela Sheth, Ravi K. Gong, In-Taek Department of Physics and Astronomy Sejong University 209 Neungdong-ro Gwangjin-gu Seoul05006 Korea Republic of Graduate Program of Astronomy and Space Science Sejong University 209 Neungdong-ro Gwangjin-gu Seoul05006 Korea Republic of Department of Physics and Astronomy University of Pennsylvania 209 South 33rd Street PhiladelphiaPA19104 United States

The central regions of nearby elliptical galaxies are dominated by baryons (stars) and provide interesting laboratories for studying the radial acceleration relation (RAR). We carry out exploratory analyses and discuss the possibility of constraining the RAR in the super-critical acceleration range (10-9.5, 10-8) m s-2using a sample of nearly round pure-bulge (spheroidal, dispersion-dominated) galaxies including 24 ATLAS3D galaxies and 4201 SDSS galaxies covering a wide range of masses, sizes and luminosity density profiles. We consider a range of current possibilities for the stellar mass-to- light ratio (M∗/L), its gradient and dark or phantom matter (DM/PM) halo profiles. We obtain the probability density functions (PDFs) of the parameters of the considered models via Bayesian infer- ence based on spherical Jeans Monte Carlo modeling of the observed velocity dispersions. We then constrain the DM/PM-to-baryon acceleration ratio aX/aB from the PDFs. Unless we ignore observed radial gradients in M∗/L, or assume unreasonably strong gradients, marginalization over nuisance fac- tors suggests aX/aB= 10p(aB/a+1)qwith p = -1.00 ± 0.03 (stat) +0.11-0.06(sys) and q = -1.02 ± 0.09 (stat) +0.16-0.00(sys) around a super-critical acceleration a+1 = 1.2 × 10-9 m s-2. In the context of the ΛCDM paradigm, this RAR suggests that the NFW DM halo profile is a reasonable description of galactic halos even after the processes of galaxy formation and evolution. In the context of the MOND paradigm, this RAR favors the Simple interpolating function but is inconsistent with the vast majority of other theoretical proposals and fitting functions motivated mainly from sub-critical acceleration data. Copyright © 2017, The Authors. All rights reserved.

关键词： Galaxies

Photovoltaic Devices: High Performance Roll‐to‐Roll Produced Fullerene‐Free Organic Photovoltaic Devices via Temperature‐Controlled Slot Die Coating (Adv. Funct. Mater. 6/2019)

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Advanced Functional Materials 2019年第6期29卷

作者： Seok‐In Na You‐Hyun Seo Yoon‐Chae Nah Seok‐Soon Kim Hyojung Heo Jueng‐Eun Kim Nicholas Rolston Reinhold H. Dauskardt Mei Gao Youngu Lee Doojin Vak CSIRO Manufacturing Bag 10 Clayton South Victoria 3168 Australia Professional Graduate School of Flexible and Printable Electronics and Polymer Materials Fusion Research Center Chonbuk National University Deokjin‐dong 664‐14 Jeonju‐si Jeollabuk‐do 561‐756 Republic of Korea Interdisciplinary Program in Creative Engineering School of Energy Materials and Chemical Engineering Korea University of Technology and Education Cheonan 31253 Korea Department of Nano & Chemical Engineering Kunsan National University 290–2 Miryong‐dong Gunsan‐si Jeollabuk‐do 573‐701 Republic of Korea Department of Energy Science and Engineering Daegu Gyeongbuk Institute of Science and Technology (DGIST) Daegu 42988 Korea Department of Applied Physics Stanford University Stanford CA 94305 USA Department of Materials Science and Engineering Stanford University Stanford CA 94305 USA

Water Splitting: Creation of 3D Textured Graphene/Si Schottky Junction Photocathode for Enhanced Photo‐Electrochemical Efficiency and Stability (Adv. Energy Mater. 29/2019)

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Advanced Energy Materials 2019年第29期9卷

作者： Che‐Kuei Ku Po‐Hsien Wu Cheng‐Chu Chung Chun‐Chi Chen Kai‐Jie Tsai Hung‐Ming Chen Yu‐Cheng Chang Cheng‐Hao Chuang Chuan‐Yu Wei Cheng‐Yen Wen Tzu‐Yao Lin Hsuen‐Li Chen Yen‐Shang Wang Zhe‐Yu Lee Jun‐Ru Chang Chih‐Wei Luo Di‐Yan Wang Bing Joe Hwang Chun‐Wei Chen Department of Materials Science and Engineering National Taiwan University Taipei 10617 Taiwan Department of Chemical Engineering National Taiwan University of Science and Technology Taipei 106 Taiwan Gingen Technology Co. Ltd New Taipei City 11054 Taiwan Department of Physics Tamkang University Tamsui 25137 Taiwan Department of Electrophysics National Chiao Tung University No. 1001 University Rd. Hsinchu 300 Taiwan Department of Chemistry Tunghai University Taichung 40704 Taiwan Center for Nanoscience and Technology Tunghai University Taichung 40704 Taiwan National Synchrotron Radiation Research Center Hsinchu 30076 Taiwan Center of Atomic Initiative for New Materials (AI‐MAT) National Taiwan University Taipei 10617 Taiwan International Graduate Program of Molecular Science and Technology National Taiwan University (NTU‐MST) Taipei 10617 Taiwan

Understanding the students’ conception about electric current, voltage, and resistance

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AIP Conference Proceedings 2018年第1期2014卷

作者： Dewanta Arya Nugraha Arifian Dimas Nita Depit Setyani A. Suparmi Retno Winarni 1Natural Sciences Education Doctoral Program Universitas Sebelas Maret Surakarta INDONESIA 2Science Education Graduate Program Universitas Sebelas Maret Surakarta INDONESIA 3Departemen of Physics Universitas Sebelas Maret Surakarta INDONESIA 4Primary School Teacher Education Departement (PGSD) Faculty of Teacher Training and Education Universitas Sebelas Maret INDONESIA

The purpose of this study is to explore the understanding of the concept of students in understanding the concept of dynamic electricity. The subjects were 32 physics students of Universitas Sebelas Maret, Surakarta, Indonesia. The instrument used is a conceptual question about the electrical dynamic. Data collected from student tests and arguments. Based on the research data, on the discussion of electric current, as much as 43,13% of students have correct conception. In the discussion voltage, as much as 46,09% of students have an accurate understanding. In the discussion of resistance, as much as 55,21% of students have correct conception. It can conclude that there are still many students who have difficulty in understanding the concept of electrical current, electric voltage, and electrical resistance. Advised to do further research to explore the causes of misconceptions experienced by students to find the best way to teach the concept.

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Riddling: Chimera's dilemma

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arXiv 2018年

作者： Santos, V. Szezech, J.D. Batista, A.M. Iarosz, K.C. Baptista, M.S. Ren, H.P. Grebogi, C. Viana, R.L. Caldas, I.L. Maistrenko, Y.L. Kurths, J. Graduate in Science Program State University of Ponta Grossa Ponta Grossa Paraná84030-900 Brazil Department of Mathematics and Statistics State University of Ponta Grossa Ponta Grossa Paraná84030-900 Brazil Potsdam Institute for Climate Impact Research Potsdam Brandenburg14473 Germany Institute of Physics University of São Paulo São Paulo05508-900 Brazil Department of Physics Humboldt University Berlin Brandenburg12489 Germany Institute for Complex Systems and Mathematical Biology SUPA University of Aberdeen Aberdeen ScotlandAB24 3UE United Kingdom Shaanxi Key Laboratory of Complex System Control and Intelligent Information Processing Xian University of Technology Xi'an710048 China Xian Technological University Xi'an710021 China Department of Physics Federal University of Paraná Curitiba Paraná80060-000 Brazil Institute of Mathematics Centre for Medical and Biotechnical Research National Academy of Sciences of Ukraine Tereshchenkivska St. 3 Kyiv01030 Ukraine

We investigate the basin of attraction properties and its boundaries for chimera states in a circulant network of Hénon maps. It is known that coexisting basins of attraction lead to a hysteretic behaviour in the diagrams of the density of states as a function of a varying parameter. Chimera states, for which coherent and incoherent domains occur simultaneously, emerge as a consequence of the coexistence of basin of attractions for each state. Consequently, the distribution of chimera states can remain invariant by a parameter change, as well as it can suffer subtle changes when one of the basins ceases to exist. A similar phenomenon is observed when perturbations are applied in the initial conditions. By means of the uncertainty exponent, we characterise the basin boundaries between the coherent and chimera states, and between the incoherent and chimera states, respectively. This way, we show that the density of chimera states can be not only moderately sensitive but also highly sensitive to initial conditions. This chimera's dilemma is a consequence of the fractal and riddled nature of the basins boundaries. Coupled dynamical systems have been used to describe the behaviour of real complex systems, such as power grids, neuronal networks, economics, and chemical reactions. Furthermore, these systems can exhibit various kinds of interesting nonlinear dynamics, e.g. synchronisation, chaotic oscillations, and chimera states. The chimera state is a spatio-temporal pattern characterised by the coexistence of coherent and incoherent dynamics. It has been observed in a great variety of systems, ranging from theoretical and experimental arrays of oscillators, to in phenomena such as the unihemispheric sleep of cetaceans. We study the chimera state in a circulant network of Hénon maps, seeking to determine how the density of states in the network depends on the system parameters and the initial conditions. We have found that, as expected, the density of states might be inva

关键词： Neurons

Potential Fluctuations at Low Temperatures in Mesoscopic-Scale SmTiO3/SrTiO3/SmTiO3 Quantum Well Structures

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arXiv 2017年

作者： Hardy, Will J. Isaac, Brandon Marshall, Patrick Mikheev, Evgeny Zhou, Panpan Stemmer, Susanne Natelson, Douglas Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX United States Materials Department University of California Santa BarbaraCA United States Department of Physics and Astronomy Rice University HoustonTX United States Department of Electrical and Computer Engineering Rice University HoustonTX United States Department of Materials Science and Nanoengineering Rice University HoustonTX United States

Heterointerfaces of SrTiO3 with other transition metal oxides make up an intriguing family of systems with a bounty of coexisting and competing physical orders. Some examples, such as LaAlO3/SrTiO3, support a high carrier density electron gas at the interface whose electronic properties are determined by a combination of lattice distortions, spin-orbit coupling, defects, and various regimes of magnetic and charge ordering. Here, we study electronic transport in mesoscale devices made with heterostructures of SrTiO3 sandwiched between layers of SmTiO3, in which the transport properties can be tuned from a regime of Fermi-liquid like resistivity (ρ ∝ T2) to a non-Fermi liquid (ρ ∝ T5/3) by controlling the SrTiO3 thickness. In mesoscale devices at low temperatures, we find unexpected voltage fluctuations that grow in magnitude as T is decreased below 20 K, are suppressed with increasing contact electrode size, and are independent of the drive current and contact spacing distance. Magnetoresistance fluctuations are also observed, which are reminiscent of universal conductance fluctuations but not entirely consistent with their conventional properties. Candidate explanations are considered, and a mechanism is suggested based on mesoscopic temporal fluctuations of the Seebeck coefficient. An improved understanding of charge transport in these model systems, especially their quantum coherent properties, may lead to insights into the nature of transport in strongly correlated materials that deviate from Fermi liquid theory. Copyright © 2017, The Authors. All rights reserved.

关键词： Rare earths

Hypostatic jammed packings of frictionless nonspherical particles

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arXiv 2017年

作者： VanderWerf, Kyle Jin, Weiwei Shattuck, Mark D. O'Hern, Corey S. Department of Physics Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department City College of New York New YorkNY10031 United States Department of Mechanics and Engineering Science Peking University Beijing100871 China Department of Mechanical Engineering & Materials Science Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States

We perform computational studies of static packings of a variety of nonspherical particles including circulo-lines, circulo-polygons, ellipses, asymmetric dimers, dumbbells, and others to determine which shapes form packings with fewer contacts than degrees of freedom (hypostatic packings) and which have equal numbers of contacts and degrees of freedom (isostatic packings), and to understand why hypostatic packings of nonspherical particles can be mechanically stable despite having fewer contacts than that predicted from naïve constraint counting. To generate highly accurate force- and torque-balanced packings of circulo-lines and -polygons, we developed an interparticle potential that gives continuous forces and torques as a function of the particle coordinates. We show that the packing fraction and coordination number at jamming onset obey a master-like form for all of the nonspherical particle packings we studied when plotted versus the particle asphericity A, which is proportional to the ratio of the squared perimeter to the area of the particle. Further, the eigenvalue spectra of the dynamical matrix for packings of different particle shapes collapse when plotted at the same A. For hypostatic packings of nonspherical particles, we verify that the number of "quartic" modes along which the potential energy increases as the fourth power of the perturbation amplitude matches the number of missing contacts relative to the isostatic value. We show that the fourth derivatives of the total potential energy in the directions of the quartic modes remain nonzero as the pressure of the packings is decreased to zero. In addition, we calculate the principal curvatures of the inequality constraints for each contact in circulo-line packings and identify specific types of contacts with inequality constraints that possess convex curvature. These contacts can constrain multiple degrees of freedom and allow hypostatic packings of nonspherical particles to be mechanically stable. C

关键词： Degrees of freedom (mechanics)