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Condensed Matter Physics Commons™

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Atomic, Molecular and Optical Physics

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Articles 211 - 240 of 303

Full-Text Articles in Condensed Matter Physics

Experimental Design And Construction For Critical Velocity Measurement In Spin-Orbit Coupled Bose-Einstein Condensates, Ting-Wei Hsu, Yong P. Chen Aug 2015

Experimental Design And Construction For Critical Velocity Measurement In Spin-Orbit Coupled Bose-Einstein Condensates, Ting-Wei Hsu, Yong P. Chen

The Summer Undergraduate Research Fellowship (SURF) Symposium

Quantum simulation using ultra-cold atoms, such as Bose-Einstein Condensates (BECs), offers a very flexible and well controlled environment to simulate physics in different systems. For example, to simulate the effects of spin orbit coupling (SOC) on electrons in solid state systems, we can make a SOC BEC which mimics the behavior of SOC electrons. The goal of this project is to see how the superfluid property of BECs change in the presence of SOC. In particular, we plan to measure the critical velocity of an 87Rb BEC with and without SOC by stirring it with a laser. This laser needs …

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Retrieving Spin Textures On Curved Magnetic Thin Films With Full-Field Soft X-Ray Microscopies, Robert Streubel, Florian Kronast, Peter Fischer, Dula Parkinson, Oliver G. Schmidt, Denys Makarov Jul 2015

Retrieving Spin Textures On Curved Magnetic Thin Films With Full-Field Soft X-Ray Microscopies, Robert Streubel, Florian Kronast, Peter Fischer, Dula Parkinson, Oliver G. Schmidt, Denys Makarov

Robert Streubel Papers

X-ray tomography is a well-established technique to characterize 3D structures in material sciences and biology; its magnetic analogue - magnetic X-ray tomography - is yet to be developed. Here we demonstrate the visualization and reconstruction of magnetic domain structures in a 3D curved magnetic thin films with tubular shape by means of full-field soft X-ray microscopies. The 3D arrangement of the magnetization is retrieved from a set of 2D projections by analysing the evolution of the magnetic contrast with varying projection angle. Using reconstruction algorithms to analyse the angular evolution of 2D projections provides quantitative information about domain patterns and …

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Plotting The Van Der Waals Fluid In Pseudo-3d And The Maxwell Construction, Carl W. David Jul 2015

Plotting The Van Der Waals Fluid In Pseudo-3d And The Maxwell Construction, Carl W. David

Chemistry Education Materials

The van der Waals (from his thesis of 1873) equation is a cubic in the molar volume. Plotting the equation in pseudo 3 dimensions is quite simple to do, but including tie lines is quite difficult. Employing the solutions to the cubic van der Waals equation, the tie lines are readily available and can be easily incorporated into the aforementioned 3D plots.

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Modelling Transient Terahertz Magneto-Spectroscopy Measurements Of P-Type Cvd Graphene Leading To A Negative Photoconductivity., Rhyan Foo Kune May 2015

Modelling Transient Terahertz Magneto-Spectroscopy Measurements Of P-Type Cvd Graphene Leading To A Negative Photoconductivity., Rhyan Foo Kune

Macalester Journal of Physics and Astronomy

Ultrafast Terahertz (THz) Magneto-Spectroscopy (UTMS) measurements were performed on p-type CVD graphene sample to investigate the intrinsic carrier dynamics of the material. We investigated static and time-resolved THz transmission measurements, in which the sample was photo-excited by a near infrared (NIR) pump pulse, in order to study its behavior in a magnetic field. In these measurements the free carriers were probed to independently measure the carrier density and scattering rate in this film. We observed, in our graphene sample, an increase in transmission related to a negative photoconductivity (decrease in conductivity after photoexcitation) consistent with previous research. This decrease is …

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Enhancement Of Local Piezoresponse In Polymer Ferroelectrics Via Nanoscale Control Of Microstructure, Yoon-Young Choi, Pankaj Sharma, Charudatta Phatak, David J. Gosztola, Yunya Liu, Joonseok Lee, Byeongdu Lee, Jiangyu Li, Alexei Gruverman, Stephen Ducharme, Seungbum Hong Feb 2015

Enhancement Of Local Piezoresponse In Polymer Ferroelectrics Via Nanoscale Control Of Microstructure, Yoon-Young Choi, Pankaj Sharma, Charudatta Phatak, David J. Gosztola, Yunya Liu, Joonseok Lee, Byeongdu Lee, Jiangyu Li, Alexei Gruverman, Stephen Ducharme, Seungbum Hong

Stephen Ducharme Publications

Polymer ferroelectrics are flexible and lightweight electromechanical materials that are widely studied due to their potential application as sensors, actuators, and energy harvesters. However, one of the biggest challenges is their low piezoelectric coefficient. Here, we report a mechanical annealing effect based on local pressure induced by a nanoscale tip that enhances the local piezoresponse. This process can control the nanoscale material properties over a microscale area at room temperature. We attribute this improvement to the formation and growth of β-phase extended chain crystals via sliding diffusion and crystal alignment along the scan axis under high mechanical stress. We believe …

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Magnetic Force Microscopy Study Of Zr2co11-Based Nanocrystalline Materials: Effect Of Mo Addition, Lanping Yue, Yunlong Jin, Wenyong Zhang, David J. Sellmyer Jan 2015

Magnetic Force Microscopy Study Of Zr2co11-Based Nanocrystalline Materials: Effect Of Mo Addition, Lanping Yue, Yunlong Jin, Wenyong Zhang, David J. Sellmyer

Nebraska Center for Materials and Nanoscience: Faculty Publications

The addition of Molybdenum was used to modify the nanostructure and enhance coercivity of rare-earth-free Zr2Co11-based nanocrystalline permanent magnets. The effect of Mo addition on magnetic domain structures of melt spun nanocrystalline Zr16Co84−xMox (𝑥 = 0, 0.5, 1, 1.5, and 2.0) ribbons has been investigated. It was found that magnetic properties and local domain structures are strongly influenced by Mo doping. The coercivity of the samples increases with the increase in Mo content (𝑥 ≤ 1.5). The maximum energy product (𝐵𝐻)max increases with increasing 𝑥 from 0.5 MGOe for 𝑥 …

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Magnetic Chiral Spin Textures By Imprinting, Robert Streubel, F. Kronast, U. Rössler, O. G. Schmidt, P. Fischer, D. Makarov Jan 2015

Magnetic Chiral Spin Textures By Imprinting, Robert Streubel, F. Kronast, U. Rössler, O. G. Schmidt, P. Fischer, D. Makarov

Robert Streubel Papers

The unique properties of non-trivial topological states, e.g. magnetic skyrmions [1] may path the way towards novel spintronic devices [2]. However, these spin textures have only been observed in special classes of materials possessing non-centrosymmetric crystal structure [1,3-6] and at low temperatures, which limits their application potential. We offer an alternate route to design synthetic magnetic heterostructures that resemble swirls, vortices or skyrmions with distinct topological charge densities at room temperature. By vertically stacking two magnetic nanopatterns with in-and out-of-plane magnetization and tailoring the interlayer exchange coupling, non-collinear spin textures with tunable topological charge can be imprinted (Fig. 1a).

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Manipulating Topological States By Imprinting Non-Collinear Spin Textures, Robert Streubel, Luyang Han, Mi Young Im, Florian Kronast, Ulrich K. Rößler, Florin Radu, Radu Abrudan, Gungun Lin, Oliver G. Schmidt, Peter Fischer, Denys Makarov Jan 2015

Manipulating Topological States By Imprinting Non-Collinear Spin Textures, Robert Streubel, Luyang Han, Mi Young Im, Florian Kronast, Ulrich K. Rößler, Florin Radu, Radu Abrudan, Gungun Lin, Oliver G. Schmidt, Peter Fischer, Denys Makarov

Robert Streubel Papers

Topological magnetic states, such as chiral skyrmions, are of great scientific interest and show huge potential for novel spintronics applications, provided their topological charges can be fully controlled. So far skyrmionic textures have been observed in noncentrosymmetric crystalline materials with low symmetry and at low temperatures. We propose theoretically and demonstrate experimentally the design of spin textures with topological charge densities that can be tailored at ambient temperatures. Tuning the interlayer coupling in vertically stacked nanopatterned magnetic heterostructures, such as a model system of a Co/Pd multilayer coupled to Permalloy, the in-plane non-collinear spin texture of one layer can be …

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Multiferroic Tunnel Junctions And Ferroelectric Control Of Magnetic State At Interface, Y. W. Yin, M. Raju, W. J. Hu, John D. Burton, Y.-M. Kim, A. Y. Borisevich, S. J. Pennycook, S. M. Yang, T. W. Noh, Alexei Gruverman, X. G. Li, Z. D. Zhang, Evgeny Y. Tsymbal, Qi Li Jan 2015

Multiferroic Tunnel Junctions And Ferroelectric Control Of Magnetic State At Interface, Y. W. Yin, M. Raju, W. J. Hu, John D. Burton, Y.-M. Kim, A. Y. Borisevich, S. J. Pennycook, S. M. Yang, T. W. Noh, Alexei Gruverman, X. G. Li, Z. D. Zhang, Evgeny Y. Tsymbal, Qi Li

Alexei Gruverman Publications

As semiconductor devices reach ever smaller dimensions, the challenge of power dissipation and quantum effect place a serious limit on the future device scaling. Recently, a multiferroic tunnel junction (MFTJ) with a ferroelectric barrier sandwiched between two ferromagnetic electrodes has drawn enormous interest due to its potential applications not only in multi-level data storage but also in electric field controlled spintronics and nanoferronics. Here, we present our investigations on four-level resistance states, giant tunneling electroresistance (TER) due to interfacial magnetoelectric coupling, and ferroelectric control of spin polarized tunneling in MFTJs. Coexistence of large tunneling magnetoresistance and TER has been observed …

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Electrostatic Charge On Flying Hummingbirds And Its Potential Role In Pollination, Marc Badger, Victor Manuel Ortega-Jimenez, Lisa Von Ribenau, Ashley Smiley, Robert Dudley, Alexei Gruverman , Editor Jan 2015

Electrostatic Charge On Flying Hummingbirds And Its Potential Role In Pollination, Marc Badger, Victor Manuel Ortega-Jimenez, Lisa Von Ribenau, Ashley Smiley, Robert Dudley, Alexei Gruverman , Editor

Alexei Gruverman Publications

Electrostatic phenomena are known to enhance both wind- and insect-mediated pollination, but have not yet been described for nectar-feeding vertebrates. Here we demonstrate that wild Anna's Hummingbirds (Calypte anna) can carry positive charges up to 800 pC while in flight (mean ± s.d.: 66 ± 129 pC). Triboelectric charging obtained by rubbing an isolated hummingbird wing against various plant structures generated charges up to 700 pC. A metal hummingbird model charged to 400 pC induced bending of floral stamens in four plants (Nicotiana, Hemerocallis, Penstemon, and Aloe spp.), and also attracted falling Lycopodium spores at distances of < 2 mm. Electrostatic forces may therefore influence pollen transfer onto nectar-feeding birds.

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Magnetic Soft X-Ray Tomography Of Magnetic Swiss Roll Architectures, Robert Streubel, F. Kronast, P. Fischer, O. G. Schmidt, D. Makarov Jan 2015

Magnetic Soft X-Ray Tomography Of Magnetic Swiss Roll Architectures, Robert Streubel, F. Kronast, P. Fischer, O. G. Schmidt, D. Makarov

Robert Streubel Papers

A further increase in performance of state-of-the-art spin-electronics can be achieved by either miniaturizing its functional components or harnessing the third dimension. The first route, however, faces physical limitations as properties of nanostructures and their response to external stimuli can drastically change in reduced dimensions. An alternative way is to go from planar 2D structures to 3D architectures [1]. Such 3D functional elements can be obtained for example by rolling up initially planar strained thin films into Swiss roll like objects with multiple windings (Fig. 1a). A major advantage of this technology platform is the possibility to fabricate compact multifunctional …

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Wigner High-Electron-Correlation Regime Of Nonuniform Density Systems: A Quantal-Density-Functional-Theory Study, Douglas Achan, Lou Massa, Viraht Sahni Aug 2014

Wigner High-Electron-Correlation Regime Of Nonuniform Density Systems: A Quantal-Density-Functional-Theory Study, Douglas Achan, Lou Massa, Viraht Sahni

Publications and Research

The Wigner regime of a system of electrons in an external field is characterized by a low electron density and a high electron-interaction energy relative to the kinetic energy. The low-correlation regime is in turn described by a high electron density and an electron-interaction energy smaller than the kinetic energy. The Wigner regime of a nonuniform-electron-density system is investigated via quantal density functional theory (QDFT). Within QDFT, the contributions of electron correlations due to the Pauli exclusion principle, Coulomb repulsion, and correlation-kinetic effects are separately delineated and explicitly defined. The nonuniform-electron-density system studied is that of the Hooke's atom in …

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Environmental Testing Of Lasers For Jpl's Cold Atom Laboratory, Carey L. Baxter Aug 2014

Environmental Testing Of Lasers For Jpl's Cold Atom Laboratory, Carey L. Baxter

STAR Program Research Presentations

NASA’s Cold Atom Lab (CAL) is a multi-user facility designed to study ultra-cold quantum gases in the microgravity environment of the International Space Station (ISS). One of the main goals of CAL is to explore the unknown territory of extremely low temperatures—possibly as low as the picokelvin range!—where new and fascinating quantum phenomena can be observed. At such temperatures matter stops behaving as particles and instead becomes macroscopic matter waves. CAL will be remotely controlled to perform a multitude of experiments and is scheduled to launch in 2016. In order to anticipate problems that might occur during and post-launch, including …

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First-Principles Atomistic Simulations Of Energetic Materials, Aaron Christopher Landerville Apr 2014

First-Principles Atomistic Simulations Of Energetic Materials, Aaron Christopher Landerville

USF Tampa Graduate Theses and Dissertations

This dissertation is concerned with the understanding of physico-chemical properties of energetic materials (EMs). Recently, a substantial amount of work has been directed towards calculations of equations of state and structural changes upon compression of existing EMs, as well as elucidating the underlying chemistry of initiation in detonating EMs. This work contributes to this effort by 1) predicting equations of state and thermo-physical properties of EMs, 2) predicting new phases of novel EMs, and 3) examining the initial stages of chemistry that result in detonation in EMs. The motivation for the first thrust, is to provide thermodynamic properties as input …

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A Low-Power Optical Electron Switch, Wayne Cheng-Wei Huang, Roger Bach, Peter Beierle, Herman Batelaan Feb 2014

A Low-Power Optical Electron Switch, Wayne Cheng-Wei Huang, Roger Bach, Peter Beierle, Herman Batelaan

Department of Physics and Astronomy: Faculty Publications

An electron beam is deflected when it passes over a silicon-nitride surface, if the surface is illuminated by a low-power continuous-wave diode laser. A deflection angle of up to 1.2 mrad is achieved for an electron beam of 29 μrad divergence. A mechanical beam-stop is used to demonstrate that the effect can act as an optical electron switch with a rise and fall time of 6 μs. Such a switch provides an alternative means to control electron beams, which may be useful in electron lithography and microscopy.

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Wave Function For Harmonically Confined Electrons In Time-Dependent Electric And Magnetostatic Fields, Hong-Ming Zhu, Jin-Wang Chen, Xiao-Yin Pan, Viraht Sahni Jan 2014

Wave Function For Harmonically Confined Electrons In Time-Dependent Electric And Magnetostatic Fields, Hong-Ming Zhu, Jin-Wang Chen, Xiao-Yin Pan, Viraht Sahni

Publications and Research

We derive via the interaction “representation” the many-body wave function for harmonically confined electrons in the presence of a magnetostatic field and perturbed by a spatially homogeneous time-dependent electric field—the Generalized Kohn Theorem (GKT) wave function. In the absence of the harmonic confinement – the uniform electron gas – the GKT wave function reduces to the Kohn Theorem wave function. Without the magnetostatic field, the GKTwave function is the Harmonic Potential Theorem wave function. We further prove the validity of the connection between the GKT wave function derived and the system in an accelerated frame of reference. Finally, we provide …

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Structural And Electronic Origin Of The Magnetic Structures In Hexagonal Lufeo3, Hongwei Wang, Igor V. Solovyev, Wenbin Wang, Xiao Wang, Philip J. Ryan, David J. Keavney, Jong-Woo Kim, Thomas Z. Ward, Leyi Zhu, Jian Shen, X. M. Cheng, Lixin He, Xiaoshan Xu, Xifan Wu Jan 2014

Structural And Electronic Origin Of The Magnetic Structures In Hexagonal Lufeo3, Hongwei Wang, Igor V. Solovyev, Wenbin Wang, Xiao Wang, Philip J. Ryan, David J. Keavney, Jong-Woo Kim, Thomas Z. Ward, Leyi Zhu, Jian Shen, X. M. Cheng, Lixin He, Xiaoshan Xu, Xifan Wu

Xiaoshan Xu Papers

Using combined theoretical and experimental approaches, we studied the structural and electronic origin of the magnetic structure in hexagonal LuFeO3. Besides showing the strong exchange coupling that is consistent with the high magnetic ordering temperature, the previously observed spin reorientation transition is explained by the theoretically calculated magnetic phase diagram. The structural origin of this spin reorientation that is responsible for the appearance of spontaneous magnetization, is identified by theory and verified by x-ray diffraction and absorption experiments.

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Multiferroic Hexagonal Ferrites (H-Rfeo3, R=Y, Dy-Lu): An Experimental Review, Xiaoshan Xu, Wenbin Wang Jan 2014

Multiferroic Hexagonal Ferrites (H-Rfeo3, R=Y, Dy-Lu): An Experimental Review, Xiaoshan Xu, Wenbin Wang

Xiaoshan Xu Papers

Hexagonal ferrites (h-RFeO3, R=Y, Dy-Lu) have recently been identified as a new family of multiferroic complex oxides. The coexisting spontaneous electric and magnetic polarizations make h-RFeO3 rare-case ferroelectric ferromagnets at low temperature. Plus the room-temperature mul- tiferroicity and predicted magnetoelectric effect, h-RFeO3 are promising materials for multiferroic applications. Here we review the structural, ferroelectric, magnetic, and magnetoelectric properties of h-RFeO3. The thin film growth is also discussed because it is critical in making high quality single crystalline materials for studying intrinsic properties.

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Spin Density Waves In Periodically Strained Graphene Nanoribbons, Nabil M. Al-Aqtash, Renat F. Sabirianov Jan 2014

Spin Density Waves In Periodically Strained Graphene Nanoribbons, Nabil M. Al-Aqtash, Renat F. Sabirianov

Nebraska Center for Materials and Nanoscience: Faculty Publications

Zigzag graphene nanoribbons (ZGNRs) are antiferromagnetic in the ground state with zero net magnetization due to the compensation of contributions from opposite edges. Uniform deformations (both shear and axial) do not produce magnetization due to symmetry restrictions. However, we report the results of first-principles calculations that predict the induction of spin density waves (SDWs) in ZGNRs under non-uniform periodic strain. Using the density functional theory (DFT) method, we show that a sinusoidal magnetization variation along the axis of the ribbon occurs under a sinusoidal transversal shear strain. SDWs appear due to the presence of a strain gradient that induced asymmetry …

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Active Control Of Magnetoresistance Of Organic Spin Valves Using Ferroelectricity, Dali Sun, Mei Fang, Xiaoshan Xu, Lu Jiang, Hangwen Guo, Yanmei Wang, Wenting Yang, Lifeng Yin, Paul C. Snijders, T. Z. Ward, Zheng Gai, X. -G. Zhang, Ho Nyung Lee, Jian Shen Jan 2014

Active Control Of Magnetoresistance Of Organic Spin Valves Using Ferroelectricity, Dali Sun, Mei Fang, Xiaoshan Xu, Lu Jiang, Hangwen Guo, Yanmei Wang, Wenting Yang, Lifeng Yin, Paul C. Snijders, T. Z. Ward, Zheng Gai, X. -G. Zhang, Ho Nyung Lee, Jian Shen

Xiaoshan Xu Papers

Organic spintronic devices have been appealing because of the long spin lifetime of the charge carriers in the organic materials and their low cost, flexibility and chemical diversity. In previous studies, the control of resistance of organic spin valves is generally achieved by the alignment of the magnetization directions of the two ferromagnetic electrodes, generating magnetoresistance. Here we employ a new knob to tune the resistance of organic spin valves by adding a thin ferroelectric interfacial layer between the ferromagnetic electrode and the organic spacer: the magnetoresistance of the spin valve depends strongly on the history of the bias voltage, …

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Positive Exchange Bias In Epitaxial Permalloy/Mgo Integrated With Si (100), S. S. Rao, J. T. Prater, Fan Wu, S. Nori, D. Kumar, Lanping Yue, Sy_Hwang Liou, Jagdish Narayan Jan 2014

Positive Exchange Bias In Epitaxial Permalloy/Mgo Integrated With Si (100), S. S. Rao, J. T. Prater, Fan Wu, S. Nori, D. Kumar, Lanping Yue, Sy_Hwang Liou, Jagdish Narayan

Sy-Hwang Liou Publications

In magnetic random access memory (MRAM) devices, soft magnetic thin film elements such as permalloy (Py) are used as unit cells of information. The epitaxial integration of these elements with the technologically important substrate Si (100) and a thorough understanding of their magnetic properties are critical for CMOS-based magnetic devices. We report on the epitaxial growth of Ni82.5Fe17.5 (permalloy, Py) on Si (100) using a TiN/MgO buffer layer. Initial stages of growth are characterized by the formation of discrete islands that gradually merge into a continuous film as deposition times are extended. Interestingly, we find that the …

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Coplanar Switching Of Polarization In Thin Films Of Vinylidene Fluoride Oligomers, Pankaj Sharma, Alexandra Fursina, Shashi Poddar, Stephen Ducharme, Alexei Gruverman Jan 2014

Coplanar Switching Of Polarization In Thin Films Of Vinylidene Fluoride Oligomers, Pankaj Sharma, Alexandra Fursina, Shashi Poddar, Stephen Ducharme, Alexei Gruverman

Stephen Ducharme Publications

Switching characteristics of vinylidene fluoride oligomer thin films with molecular chains aligned normal to the substrate and exhibiting a preferential in-plane polarization have been investigated using coplanar geometry of inter-digital electrodes via high-resolution piezoresponse force microscopy. It has been shown that in-plane switching proceeds via non-180 rotation of dipoles mediated by non-stochastic nucleation, expansion, and coalescence of domains. Asgrown multidomain configuration is found to be strongly pinned aided by charged domain walls, and the electrically induced (in-plane) mono-domain states relax to the as-grown state. The observed coercive field (approximately 0.6 MV/m) is two to three orders of magnitude smaller than …

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Laboratory Manual For Physics Of Lasers And Modern Optics, 13th Ed, Stephen Ducharme Jan 2014

Laboratory Manual For Physics Of Lasers And Modern Optics, 13th Ed, Stephen Ducharme

Stephen Ducharme Publications

You will encounter challenging puzzles and explore new and exciting physical phenomena. You will be provided with sufficient tools, guidance and other resources, but what you learn depends on your inquisitiveness and creativity. This laboratory course is designed to serve two purposes: 1) To explore a variety of physical principles using the fascinating and diverse behavior of light. 2) To learn some of the principles behind the pervasive and expanding area of optical and laser technology. This course is suitable for students of science, life sciences, and engineering, or any student who is curious about light. The prerequisites are the …

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The Spin State Of A Molecular Adsorbate Driven By The Ferroelectric Substrate Polarization†, Xin Zhang, Tatiana Palamarciuc, Jean-François Létard, Patrick Rosa, Eduardo Vega Lozada, Fernand Torres, Luis G. Rosa, Bernard Doudin, Peter A. Dowben Jan 2014

The Spin State Of A Molecular Adsorbate Driven By The Ferroelectric Substrate Polarization†, Xin Zhang, Tatiana Palamarciuc, Jean-François Létard, Patrick Rosa, Eduardo Vega Lozada, Fernand Torres, Luis G. Rosa, Bernard Doudin, Peter A. Dowben

Peter Dowben Publications

The spin state of [Fe(H2B(pz)2)2(bipy)] thin films is mediated by changes in the electric field at the interface of organic ferroelectric polyvinylidene fluoride with trifluoroethylene (PVDF–TrFE). Signatures of the molecular crossover transition are evident in changes in the unoccupied states and the related shift from diamagnetic to paramagnetic characteristics. This may point the way to the molecular magneto-electric effect on devices.

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Imaging Molecular Structures With Atomic Force Microscopy, Unurbat Erdenemunkh, Tyler Flanagan Oct 2013

Imaging Molecular Structures With Atomic Force Microscopy, Unurbat Erdenemunkh, Tyler Flanagan

Student Works

As part of the LEEP project we repaired the Atomic Force Microscopy (AFM), and wrote a user manual on using AFM. Then we scanned Self Assembly of Copolymer Films collaboration with Prof. Sergio Granados –Focil and Copper Oxide Nanocubes with Professor Prof.Luis Smith.

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Wave Function For Time-Dependent Harmonically Confined Electrons In A Time-Dependent Electric Field, Yu-Qi Li, Xiao-Yin Pan, Viraht Sahni Sep 2013

Wave Function For Time-Dependent Harmonically Confined Electrons In A Time-Dependent Electric Field, Yu-Qi Li, Xiao-Yin Pan, Viraht Sahni

Publications and Research

The many-body wave function of a system of interacting particles confined by a time-dependent harmonic potential and perturbed by a time-dependent spatially homogeneous electric field is derived via the Feynman path-integral method. The wave function is comprised of a phase factor times the solution to the unperturbed time-dependent Schrödinger equation with the latter being translated by a time-dependent value that satisfies the classical driven equation of motion. The wave function reduces to that of the Harmonic Potential Theorem wave function for the case of the time-independent harmonic confining potential.

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Use Of Zwitterionic Molecules For Forming A Hole Or Electron Transport Layer, Bernard Doudin, Pierre Braunstein, Lucie Routaboul, Guillaume Dalmas, Zhengzheng Zhang, Peter Dowben Aug 2013

Use Of Zwitterionic Molecules For Forming A Hole Or Electron Transport Layer, Bernard Doudin, Pierre Braunstein, Lucie Routaboul, Guillaume Dalmas, Zhengzheng Zhang, Peter Dowben

Peter Dowben Publications

The invention relates to the use of zwitterionic molecules for forming a hole or electron transport layer. The preferred zwitterionic molecules of the invention are derivatives of p-benzoquinonemonoimines. The invention is useful in the field of electronic devices in particular.

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Strain-Mediated Elastic Coupling In Magnetoelectric Nickel/Barium-Titanate Heterostructures, Robert Streubel, Denny Köhler, Rudolf Schäfer, Lukas M. Eng Feb 2013

Strain-Mediated Elastic Coupling In Magnetoelectric Nickel/Barium-Titanate Heterostructures, Robert Streubel, Denny Köhler, Rudolf Schäfer, Lukas M. Eng

Robert Streubel Papers

Multiferroic nanomaterials bear the potential for assembling a manifold of novel and smart devices. For room temperature (RT) applications, however, only the BiFeO3 single-phase perovskites are potential candidates to date. Nevertheless, vertical heterostructures separating magnetic and ferroelectric functionality into different layers are now widely proposed to circumvent this lack in materials' availability. We show here that the second approach is very profitable as illustrated by the strain-mediated coupling between such two layers, i.e., a ferroelectric barium titanate single-crystal (BTO) and a magnetostrictive nickel (Ni) thin film. Applying an electric field across the BTO substrate forces the magnetic easy axis in …

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Adherent Cells Avoid Polarization Gradients On Periodically Poled Litao3 Ferroelectrics, Christof Christophis, Elisabetta Ada Cavalcanti-Adam, Maximilian Hanke, Kenji Kitamura, Alexei Gruverman, Michael Grunze, Peter A. Dowben, Axel Rosenhahn Jan 2013

Adherent Cells Avoid Polarization Gradients On Periodically Poled Litao3 Ferroelectrics, Christof Christophis, Elisabetta Ada Cavalcanti-Adam, Maximilian Hanke, Kenji Kitamura, Alexei Gruverman, Michael Grunze, Peter A. Dowben, Axel Rosenhahn

Peter Dowben Publications

The response of fibroblast cells to periodically poled LiTaO3 ferroelectric crystals has been studied. While fibroblast cells do not show morphological differences on the two polarization directions, they show a tendency to avoid the field gradients that occur between polarization domains of the ferroelectric. The response to the field gradients is fully established after one hour, a time at which fibroblasts form their first focal contacts. If suspension cells, with a lower tendency to establish strong surface contacts are used, no influence of the field gradients is observed.

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Proton Transfer In Surface-Stabilized Chiral Motifs Of Croconic Acid, Donna A. Kunkel, James Hooper, Scott Simpson, Geoffrey Rojas, Stephen Ducharme, Timothy Usher, Eva Zurek, Axel Enders Jan 2013

Proton Transfer In Surface-Stabilized Chiral Motifs Of Croconic Acid, Donna A. Kunkel, James Hooper, Scott Simpson, Geoffrey Rojas, Stephen Ducharme, Timothy Usher, Eva Zurek, Axel Enders

Stephen Ducharme Publications

The structure and cooperative proton ordering of two-dimensional sheets of croconic acid were studied with scanning tunneling microscopy and first-principles calculations. Unlike in the crystalline form, which exhibits a pleated, densely packed polar sheet structure, the confinement of the molecules to the surface results in hydrogenbonded chiral clusters and networks. First-principles calculations suggest that the surface stabilizes networks of configurational isomers, which arise from direct hydrogen transfer between their constituent croconic acid monomers. Some of these configurations have a net polarization. It is demonstrated through constrained molecular dynamics simulations that simultaneous proton transfer between any two molecules can occur spontaneously. …

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