Open Access. Powered by Scholars. Published by Universities.^{®}
 Discipline

 Condensed Matter Physics (26)
 Quantum Physics (18)
 Engineering (6)
 Nanoscience and Nanotechnology (5)
 Statistical, Nonlinear, and Soft Matter Physics (4)

 Cosmology, Relativity, and Gravity (3)
 Optics (3)
 Atomic, Molecular and Optical Physics (3)
 Astrophysics and Astronomy (3)
 Other Physics (2)
 Probability (1)
 Fluid Dynamics (1)
 Plasma and Beam Physics (1)
 Other Materials Science and Engineering (1)
 Applied Mathematics (1)
 Materials Science and Engineering (1)
 Statistics and Probability (1)
 Numerical Analysis and Computation (1)
 Institution

 Syracuse University (43)
 Dartmouth College (27)
 Selected Works (11)
 University of Pennsylvania (2)
 Old Dominion University (2)

 Portland State University (2)
 Claremont Colleges (1)
 The University of Akron (1)
 Louisiana State University (1)
 Marshall University (1)
 University of Arkansas, Fayetteville (1)
 University of Tennessee, Knoxville (1)
 University of Central Florida (1)
 University of Nebraska  Lincoln (1)
 Seattle Pacific University (1)
 University of Colorado, Boulder (1)
 New Jersey Institute of Technology (1)
 West Virginia University (1)
 James Madison University (1)
 Publication Year
 Publication

 Physics (43)
 Open Dartmouth: Faculty Open Access Scholarship (27)
 Anthony Roy Day (3)
 Physics Faculty Publications and Presentations (2)
 Physics Faculty Publications (2)

 Department of Physics Papers (2)
 Sergey Kravchenko (2)
 Doctoral Dissertations (1)
 Electronic Theses and Dissertations (1)
 Arun Bansil (1)
 Dissertations (1)
 Honors Projects (1)
 Hsin Lin (1)
 LSU Doctoral Dissertations (1)
 Theses and Dissertations (1)
 Matthias Fuchs Publications (1)
 Xiaojuan Fan (1)
 Undergraduate Honors Theses (1)
 Department of Physics and Astronomy  Faculty Scholarship (1)
 Physics Faculty Research (1)
 Pomona Faculty Publications and Research (1)
 David R. Nelson (1)
 Thomas E. Wilson (1)
 Bernardo Barbiellini (1)
 Faculty Scholarship (1)
 Williams Honors College, Honors Research Projects (1)
 Publication Type
 File Type
Articles 1  30 of 100
FullText Articles in Physics
Nonlinear Optical Studies Of Bulk And Thin Film Complex Materials, Joel E. Taylor
Nonlinear Optical Studies Of Bulk And Thin Film Complex Materials, Joel E. Taylor
LSU Doctoral Dissertations
Nonlinear optical studies of bulk and thin film materials provide a vast playground for physical and dynamical characterization. In this thesis, we have implemented experimental methods to probe novel phase transitions in single crystals using rotational anisotropic second harmonic generation (RASHG) and carrier dynamics in thin films with timeresolved pumpprobe reflectivity. Furthermore, a novel low temperature ultrahigh vacuum system coupled to nonlinear optics has been developed to extend lab capabilities. Doping (Bi_{1x}Sb_{x})_{2}Se_{3} with antimony, the surface electronic reconstruction near x=80% was identified with RASHG by deviations in the sixfold and threefold polarization anisotropic ...
Modelling Potential Fluctuations In Double Layer Graphene Systems As A Periodic Oscillation In Electron Density & Its Effect On Coulomb Drag, Ryan Bogucki
Williams Honors College, Honors Research Projects
An expression for the drag transresistivity in a graphene double layer system exhibiting potential ﬂuctuations modelled as a periodic oscillation in electron density is derived. Our model starts from the Coulombic interaction and we derive the correlation between a sinusoidal ﬂuctuation in electron density in the ﬁrst layer and the induced electron density in the second layer. Previous models in the literature have employed an arbitrary correlation between each layer’s electron density, and the model presented is the ﬁrst attempt in the literature to explicitly derive this correlation. Recent experiments have found that the drag transresistivity in graphene double ...
Universality Class Of Explosive Percolation In BarabásiAlbert Networks, Habib E. Islam, M. K. Hassan
Universality Class Of Explosive Percolation In BarabásiAlbert Networks, Habib E. Islam, M. K. Hassan
Physics Faculty Publications
In this work, we study explosive percolation (EP) in BarabásiAlbert (BA) network, in which nodes are born with degree k = m, for both product rule (PR) and sum rule (SR) of the Achlioptas process. For m = 1 we find that the critical point t_{c} = 1 which is the maximum possible value of the relative link density t; Hence we cannot have access to the other phase like percolation in one dimension. However, for m > 1 we find that t_{c} decreases with increasing m and the critical exponents ν, α, β and γ for m > 1 are found to ...
Granular Convection And Crystallization Of A TwoDimensional Granular Medium, Donley S. Cormode
Granular Convection And Crystallization Of A TwoDimensional Granular Medium, Donley S. Cormode
Honors Projects
Granular media are everywhere from beaches to factories to your kitchen cabinets. There are a rich array of phenomena to study with granular media. These include granular convection, jamming, and crystallization. The systems tend to be macroscopic, so it is easy to collect data. The supplies are lowcost and easy to obtain. Studying granular media gives researchers the opportunity to explore foundational ideas in fields such as crystallography and condensed matter. This paper describes a simple, low cost apparatus used to study a vertically shaken twodimensional granular medium of glass beads. This paper will also describe a few preliminary studies ...
Effect Of Interstitial Fluid On The Fraction Of Flow Microstates That Precede Clogging In Granular Hoppers, Juha Koivisto, Douglas J. Durian
Effect Of Interstitial Fluid On The Fraction Of Flow Microstates That Precede Clogging In Granular Hoppers, Juha Koivisto, Douglas J. Durian
Department of Physics Papers
We report on the nature of flow events for the gravitydriven discharge of glass beads through a hole that is small enough that the hopper is susceptible to clogging. In particular, we measure the average and standard deviation of the distribution of discharged masses as a function of both hole and grain sizes. We do so in air, which is usual, but also with the system entirely submerged under water. This damps the grain dynamics and could be expected to dramatically affect the distribution of the flow events, which are described in prior work as avalanchelike. Though the flow is ...
Discrimination Between SpinDependent Charge Transport And SpinDependent Recombination In ΠConjugated Polymers By Correlated Current And ElectroluminescenceDetected Magnetic Resonance, Marzieh Kavand, Douglas Baird, Kipp Van Schooten, Hans Malissa
Discrimination Between SpinDependent Charge Transport And SpinDependent Recombination In ΠConjugated Polymers By Correlated Current And ElectroluminescenceDetected Magnetic Resonance, Marzieh Kavand, Douglas Baird, Kipp Van Schooten, Hans Malissa
Open Dartmouth: Faculty Open Access Scholarship
Spindependent processes play a crucial role in organic electronic devices. Spin coherence can give rise to spin mixing due to a number of processes such as hyperfine coupling, and leads to a range of magnetic field effects. However, it is not straightforward to differentiate between pure singlecarrier spindependent transport processes which control the current and therefore the electroluminescence, and spindependent electronhole recombination which determines the electroluminescence yield and in turn modulates the current. We therefore investigate the correlation between the dynamics of spindependent electric current and spindependent electroluminescence in two derivatives of the conjugated polymer poly(phenylenevinylene) using simultaneously measured ...
Exact Solution Of Quadratic Fermionic Hamiltonians For Arbitrary Boundary Conditions, Abhijeet Alase, Emilio Cobanera, Gerardo Ortiz, Lorenza Viola
Exact Solution Of Quadratic Fermionic Hamiltonians For Arbitrary Boundary Conditions, Abhijeet Alase, Emilio Cobanera, Gerardo Ortiz, Lorenza Viola
Open Dartmouth: Faculty Open Access Scholarship
We present a procedure for exactly diagonalizing finiterange quadratic fermionic Hamiltonians with arbitrary boundary conditions in one of D dimensions, and periodic in the remaining D−1. The key is a Hamiltoniandependent separation of the bulk from the boundary. By combining information from the two, we identify a matrix function that fully characterizes the solutions, and may be used to construct an efficiently computable indicator of bulkboundary correspondence. As an illustration, we show how our approach correctly describes the zeroenergy Majorana modes of a timereversalinvariant swave twoband superconductor in a Josephson ring configuration, and predicts that a fractional 4πperiodic Josephson ...
Divergence Of Voronoi Cell Anisotropy Vector: A ThresholdFree Characterization Of Local Structure In Amorphous Materials, Jennifer M. Rieser, Carl P. Goodrich, Andrea J. Liu, Douglas J. Durian
Divergence Of Voronoi Cell Anisotropy Vector: A ThresholdFree Characterization Of Local Structure In Amorphous Materials, Jennifer M. Rieser, Carl P. Goodrich, Andrea J. Liu, Douglas J. Durian
Department of Physics Papers
Characterizing structural inhomogeneity is an essential step in understanding the mechanical response of amorphous materials. We introduce a thresholdfree measure based on the field of vectors pointing from the center of each particle to the centroid of the Voronoi cell in which the particle resides. These vectors tend to point in toward regions of high free volume and away from regions of low free volume, reminiscent of sinks and sources in a vector field. We compute the local divergence of these vectors, where positive values correspond to overpacked regions and negative values identify underpacked regions within the material. Distributions of ...
Identification Of Photocurrents In Topological Insulators, Derek A. Bas, Rodrigo A. Muniz, Sercan Babakiray, David Lederman, J. E. Sipe, Alan D. Bristow
Identification Of Photocurrents In Topological Insulators, Derek A. Bas, Rodrigo A. Muniz, Sercan Babakiray, David Lederman, J. E. Sipe, Alan D. Bristow
Faculty Scholarship
Optical injection and detection of charge currents is an alternative to conventional transport and photoemission measurements, avoiding the necessity of invasive contact that may disturb the system being examined. This is a particular concern for analyzing the surface states of topological insulators. In this work one and twocolor sources of photocurrents are isolated and examined in epitaxial thin films of Bi2Se3. We demonstrate that optical excitation and terahertz detection simultaneously captures one and twocolor photocurrent contributions, which has not been required for other material systems. A method is devised to extract the two components, and in doing so each can ...
Monte Carlo Studies Of Underconstrained Magnetism In Ultracold Fermionic Alkaline Earth Atomic Gases, Pavao Santak
Monte Carlo Studies Of Underconstrained Magnetism In Ultracold Fermionic Alkaline Earth Atomic Gases, Pavao Santak
Undergraduate Honors Theses
Physicists have been trying to create artificial magnetic systems using ultracold atomic gases as their simulators. However, behavior of many ultracold atomic systems is not very well understood yet. Ultracold fermionic alkaline earth atomic (AEA) gases are one of those systems. In this thesis, we study the effects of thermal fluctuations on the overall macroscopic behavior of ultracold fermionic AEA gases using a particular semiclassical model. We study the AEA systems on a square lattice with periodic boundary conditions. To investigate the behavior of AEA systems under the effects of thermal fluctuations, we analyze several different types of correlation functions ...
Effective Microscopic Models For Sympathetic Cooling Of Atomic Gases, Roberto Onofrio, Bala Sundaram
Effective Microscopic Models For Sympathetic Cooling Of Atomic Gases, Roberto Onofrio, Bala Sundaram
Open Dartmouth: Faculty Open Access Scholarship
Thermalization of a system in the presence of a heat bath has been the subject of many theoretical investigations especially in the framework of solidstate physics. In this setting, the presence of a large bandwidth for the frequency distribution of the harmonic oscillators schematizing the heat bath is crucial, as emphasized in the CaldeiraLeggett model. By contrast, ultracold gases in atomic traps oscillate at welldefined frequencies and therefore seem to lie outside the CaldeiraLeggett paradigm. We introduce interaction Hamiltonians which allow us to adapt the model to an atomic physics framework. The intrinsic nonlinearity of these models differentiates them from ...
Engineering The Ground State Of Complex Oxides, Derek Joseph Meyers
Engineering The Ground State Of Complex Oxides, Derek Joseph Meyers
Theses and Dissertations
Transition metal oxides featuring strong electronelectron interactions have been at the forefront of condensed matter physics research in the past few decades due to the myriad of novel and exciting phases derived from their competing interactions. Beyond their numerous intriguing properties displayed in the bulk they have also shown to be quite susceptible to externally applied perturbation in various forms. The dominant theme of this work is the exploration of three emerging methods for engineering the ground states of these materials to access both their applicability and their deficiencies.
The first of the three methods involves a relatively new set ...
Dynamical Generation Of Floquet Majorana Flat Bands In SWave Superconductors, A. Poudel, G. Ortiz, L. Viola
Dynamical Generation Of Floquet Majorana Flat Bands In SWave Superconductors, A. Poudel, G. Ortiz, L. Viola
Open Dartmouth: Faculty Open Access Scholarship
We present quantum control techniques to engineer flat bands of symmetryprotected Majorana edge modes in s wave superconductors. Specifically, we show how periodic control may be employed for designing timeindependent effective Hamiltonians, which support Floquet Majorana flat bands, starting from equilibrium conditions that are either topologically trivial or only support individual Majorana pairs. In the first approach, a suitable modulation of the chemical potential simultaneously induces Majorana flat bands and dynamically activates a preexisting chiral symmetry which is responsible for their protection. In the second approach, the application of effective parity kicks dynamically generates a desired chiral symmetry by suppressing ...
Below Gap Optical Absorption In Gaas Driven By Intense, SingleCycle Coherent Transition Radiation, J. Goodfellow, Matthias Fuchs, D. Daranciang, S. Ghimire, F. Chen, H. Loos, D. A. Reis, A. S. Fisher, A. M. Lindenberg
Below Gap Optical Absorption In Gaas Driven By Intense, SingleCycle Coherent Transition Radiation, J. Goodfellow, Matthias Fuchs, D. Daranciang, S. Ghimire, F. Chen, H. Loos, D. A. Reis, A. S. Fisher, A. M. Lindenberg
Matthias Fuchs Publications
Singlecycle terahertz fields generated by coherent transition radiation from a relativistic electron beam are used to study the high field optical response of single crystal GaAs. Large amplitude changes in the subbandgap optical absorption are induced and probed dynamically by measuring the absorption of a broadband optical beam generated by transition radiation from the same electron bunch, providing an absolutely synchronized pump and probe geometry. This modification of the optical properties is consistent with strongfieldinduced electroabsorption. These processes are pertinent to a wide range of nonlinear terahertzdriven lightmatter interactions anticipated at acceleratorbased sources.
The Jahn–Teller Effect And Electron–Phonon Interaction In La0.25ca0.75mn1−Xcrxo3, H. Zhou, G. Li, H. Chen, R. Zheng, Xiaojuan Fan, X. Li
The Jahn–Teller Effect And Electron–Phonon Interaction In La0.25ca0.75mn1−Xcrxo3, H. Zhou, G. Li, H. Chen, R. Zheng, Xiaojuan Fan, X. Li
Xiaojuan Fan
The ultrasonic (longitudinal and transverse) velocities and the transport and magnetic properties of polycrystalline La0.25Ca0.75Mn1xCrxO3 (x = 0, 0.03, 0.05, and 0.07) have been studied systematically. It was found that with increasing Cr content, the resistivity increases, the chargeordering transition temperature TCO shifts to low temperature, and the magnetic moment of the system is strengthened. From the temperature dependence of the ultrasonic velocities, one can establish that the JahnTeller energy and phonon exchange constant decrease with increasing Cr content.
Majorana Flat Bands In S Wave Gapless Topological Superconductors, Shusa Deng, Gerardo Ortiz, Amrit Poudel, Lorenza Viola
Majorana Flat Bands In S Wave Gapless Topological Superconductors, Shusa Deng, Gerardo Ortiz, Amrit Poudel, Lorenza Viola
Open Dartmouth: Faculty Open Access Scholarship
We demonstrate how the nontrivial interplay between spinorbit coupling and nodeless swave superconductivity can drive a fully gapped twoband topological insulator into a timereversal invariant gapless topological superconductor supporting symmetryprotected Majorana flat bands. We characterize topological phase diagrams by a Z2×Z2 partial Berryphase invariant, and show that, despite the trivial crystal geometry, no unique bulkboundary correspondence exists. We trace this behavior to the anisotropic quasiparticle bulk gap closing, linear vs quadratic, and argue that this provides a unifying principle for gapless topological superconductivity. Experimental implications for tunneling conductance measurements are addressed, relevant for lead chalcogenide materials.
Superlattice Ultrasonic Generation, Thomas E. Wilson, M. Oehme, E. Kasper, HJ. L. Gossmann
Superlattice Ultrasonic Generation, Thomas E. Wilson, M. Oehme, E. Kasper, HJ. L. Gossmann
Thomas E. Wilson
We report the first experimental evidence for the resonant excitation of coherent highfrequency acoustic phonons in semiconducting doping superstructures by farinfrared laser radiation. After a gratingcoupled deltadoped silicon doping superlattice is illuminated with ~1 kW/mm2 nanosecondpulsed 246 GHz laser radiation, a delayed nanosecond pulse is detected by a superconducting bolometer at a time corresponding to the appropriate timeofflight for ballistic longitudinal acoustic phonons across the (100) silicon substrate. The absorbed phonon power density in the microbolometer is observed to be ~10 μW/mm2, in agreement with theory. The phonon pulse duration also matches the laser pulse duration. The absence ...
Universal Quantum Fluctuations Of A Cavity Mode Driven By A Josephson Junction, A. D. Armour, M. P. Blencowe, E. Brahimi, A. J. Rimberg
Universal Quantum Fluctuations Of A Cavity Mode Driven By A Josephson Junction, A. D. Armour, M. P. Blencowe, E. Brahimi, A. J. Rimberg
Open Dartmouth: Faculty Open Access Scholarship
We analyze the quantum dynamics of a superconducting cavity coupled to a voltagebiased Josephson junction. The cavity is strongly excited at resonances where the voltage energy lost by a Cooper pair traversing the circuit is a multiple of the cavity photon energy. We find that the resonances are accompanied by substantial squeezing of the quantum fluctuations of the cavity over a broad range of parameters and are able to identify regimes where the fluctuations in the system take on universal values.
Multiband S Wave Topological Superconductors: Role Of Dimensionality And Magnetic Field Response, Shusa Deng, Gerardo Ortiz, Lorenza Viola
Multiband S Wave Topological Superconductors: Role Of Dimensionality And Magnetic Field Response, Shusa Deng, Gerardo Ortiz, Lorenza Viola
Open Dartmouth: Faculty Open Access Scholarship
We further investigate a class of timereversalinvariant twoband swave topological superconductors introduced earlier [Deng, Viola, and Ortiz, Phys. Rev. Lett. 108, 036803 (2012)]. Provided that a sign reversal between the two superconducting pairing gaps is realized, the topological phase diagram can be determined exactly (within mean field) in one and two dimensions as well as in three dimensions upon restricting to the excitation spectrum of timereversalinvariant momentum modes. We show how, in the presence of timereversal symmetry, Z2 invariants that distinguish between trivial and nontrivial quantum phases can be constructed by considering only one of the Kramers’ sectors in which ...
Vortex Physics In Confined Geometries, M. Cristina Marchetti, David R. Nelson
Vortex Physics In Confined Geometries, M. Cristina Marchetti, David R. Nelson
David R. Nelson
Patterned irradiation of cuprate superconductors with columnar defects allows a new generation of experiments which can probe the properties of vortex liquids by forcing them to flow in confined geometries. Such experiments can be used to distinguish experimentally between continuous disorderdriven glass transitions of vortex matter, such as the vortex glass or the Bose glass transition, and nonequilibrium polymerlike glass transitions driven by interaction and entanglement. For continuous glass transitions, an analysis of such experiments that combines an inhomogeneous scaling theory with the hydrodynamic description of viscous flow of vortex liquids can be used to infer the critical behavior. After ...
Origin Of The Low Frequency Radiation Emitted By Radiative Polaritons Excited By Infrared Radiation In Planar La2o3 Films, Anita J. VincentJohnson, Yosep Schwab, Harkirat S. Mann, Mathieu Francoeur, James S. Hammonds Jr., Giovanna Scarel
Origin Of The Low Frequency Radiation Emitted By Radiative Polaritons Excited By Infrared Radiation In Planar La2o3 Films, Anita J. VincentJohnson, Yosep Schwab, Harkirat S. Mann, Mathieu Francoeur, James S. Hammonds Jr., Giovanna Scarel
Department of Physics and Astronomy  Faculty Scholarship
Upon excitation in thin oxide films by infrared radiation, radiative polaritons are formed with complex angular frequency ω, according to the theory of Kliewer and Fuchs (1966 Phys. Rev. 150 573). We show that radiative polaritons leak radiation with frequency ωi to the space surrounding the oxide film. The frequency ωi is the imaginary part of ω. The effects of the presence of the radiation leaked out at frequency ωi are observed experimentally and numerically in the infrared spectra of La2O3 films on silicon upon excitation by infrared radiation of the 0TH type radiative polariton. The frequency ωi is found ...
Theoretical Studies Of Structural And Electronic Properties In Transition Metal Oxides, Tsezar F. Seman
Theoretical Studies Of Structural And Electronic Properties In Transition Metal Oxides, Tsezar F. Seman
Dissertations
The following studies are presented: theory of Kedge resonant inelastic xray scattering and its application for La_{0.5}Sr_{1.5}MnO_{4}, effects of rare earth ion size on the stability of the coherent JahnTeller distortions in undoped perovskite manganites, and symmetrymodebased classical and quantum mechanical formalism of lattice dynamics.
The formula based on tightbinding approach for the calculation of Kedge resonant inelastic xray scattering (RIXS) spectrum for transition metal oxides is presented first, by extending the previous existing result to include explicit momentum dependence and a basis with multiple corehole sites. This formula is applied to layered ...
Structure And Dynamics Of High Temperature Superconductors, Jennifer Lynn Niedziela
Structure And Dynamics Of High Temperature Superconductors, Jennifer Lynn Niedziela
Doctoral Dissertations
High temperature superconductivity in iron based compounds has presented a series of complex problems to condensed matter physics since being discovered in 2008. The stalwart basis of condensed matter physics is the “strength in numbers" aspect of crystalline periodicity. Perfect crystalline periodicity has made possible the reduction of the questions of structural and electronic properties to single dimensions, increasing the tractability of these problems. Nevertheless, modern complex materials stretch these assumptions to their limits, and it is at this point where our work starts. Using neutron and xray scattering, we have conducted a series of studies on the structural disorder ...
Nanomechanical Resonator Coupled Linearly Via Its Momentum To A Quantum Point Contact, Latchezar L. Benatov, Miles P. Blencowe
Nanomechanical Resonator Coupled Linearly Via Its Momentum To A Quantum Point Contact, Latchezar L. Benatov, Miles P. Blencowe
Open Dartmouth: Faculty Open Access Scholarship
We use a BornMarkov approximated master equation approach to study the symmetrizedinfrequency current noise spectrum and the oscillator steady state of a nanoelectromechanical system where a nanoscale resonator is coupled linearly via its momentum to a quantum point contact (QPC). Our current noise spectra exhibit clear signatures of the quantum correlations between the QPC current and the backaction force on the oscillator at a value of the relative tunneling phase (η=−π/2) where such correlations are expected to be maximized. We also show that the steady state of the oscillator obeys a classical FokkerPlanck equation, but can experience thermomechanical ...
Information Content Of Spontaneous Symmetry Breaking, Marcelo Gleiser, Nikitas Stamatopoulos
Information Content Of Spontaneous Symmetry Breaking, Marcelo Gleiser, Nikitas Stamatopoulos
Open Dartmouth: Faculty Open Access Scholarship
We propose a measure of order in the context of nonequilibrium field theory and argue that this measure, which we call relative configurational entropy (RCE), may be used to quantify the emergence of coherent lowentropy configurations, such as timedependent or timeindependent topological and nontopological spatially extended structures. As an illustration, we investigate the nonequilibrium dynamics of spontaneous symmetry breaking in three spatial dimensions. In particular, we focus on a model where a real scalar field, prepared initially in a symmetric thermal state, is quenched to a brokensymmetric state. For a certain range of initial temperatures, spatially localized, longlived structures known ...
Direct Observation Of Localization Of The MinoritySpinBand Electrons In Magnetite Below The Verwey Temperature, Hisao Kobayashi, Toshihiro Nagao, Masayoshi Itou, Sakae Todo, Bernardo Barbiellini, Peter E. Mijnarends, Arun Bansil, Nobuhiko Sakai
Direct Observation Of Localization Of The MinoritySpinBand Electrons In Magnetite Below The Verwey Temperature, Hisao Kobayashi, Toshihiro Nagao, Masayoshi Itou, Sakae Todo, Bernardo Barbiellini, Peter E. Mijnarends, Arun Bansil, Nobuhiko Sakai
Bernardo Barbiellini
Twodimensional spinuncompensated momentum density distributions, $\rho_{\rm s}^{2D}({\bf p})$s, were reconstructed in magnetite at 12K and 300K from several measured directional magnetic Compton profiles. Mechanical detwinning was used to overcome severe twinning in the single crystal sample below the Verwey transition. The reconstructed $\rho_{\rm s}^{2D}({\bf p})$ in the first Brillouin zone changes from being negative at 300 K to positive at 12 K. This result provides the first clear evidence that electrons with low momenta in the minority spin bands in magnetite are localized below the Verwey transition temperature.
Topics In Electronic Structure And Spectroscopy Of Cuprates, Hsin Lin
Topics In Electronic Structure And Spectroscopy Of Cuprates, Hsin Lin
Hsin Lin
I have applied firstprinciples calculations to investigate several interrelated problems concerned with the electronic structure and spectroscopy of cuprates. The specific topics addressed in this thesis are as follows. 1. By properly including doping effects beyond rigid band filling, a longstanding problem of the missing BiO pocket in the electronic structure of Bi$_2$Sr$_2$CaCu$_2$O$_{8}$ (Bi2212) is solved. The doping effect is explained in terms of Coulombic effect between layers and is a generic property of all cuprates. 2. A systematic study for Pb/O and rareearth doping in Bi2212 is carried out to ...
Majorana Modes In TimeReversal Invariant S Wave Topological Superconductors, Shusa Deng, Lorenza Viola, Gerardo Ortiz
Majorana Modes In TimeReversal Invariant S Wave Topological Superconductors, Shusa Deng, Lorenza Viola, Gerardo Ortiz
Open Dartmouth: Faculty Open Access Scholarship
We present a timereversal invariant swave superconductor supporting Majorana edge modes. The multiband character of the model together with spinorbit coupling are key to realizing such a topological superconductor. We characterize the topological phase diagram by using a partial Chern number sum, and show that the latter is physically related to the parity of the fermion number of the timereversal invariant modes. By taking the selfconsistency constraint on the swave pairing gap into account, we also establish the possibility of a direct topological superconductortotopological insulator quantum phase transition.
Experimental Characterization Of Coherent Magnetization Transport In A OneDimensional Spin System, Chandrasekhar Ramanathan, Paola Cappellaro, Lorenza Viola, David G. Cory
Experimental Characterization Of Coherent Magnetization Transport In A OneDimensional Spin System, Chandrasekhar Ramanathan, Paola Cappellaro, Lorenza Viola, David G. Cory
Open Dartmouth: Faculty Open Access Scholarship
We experimentally characterize the nonequilibrium, roomtemperature magnetization dynamics of a spin chain evolving under an effective doublequantum (DQ) Hamiltonian. We show that the Liouville space operators corresponding to the magnetization and the twospin correlations evolve 90 degrees out of phase with each other, and drive the transport dynamics. For a nearestneighborcoupled Nspin chain, the dynamics are found to be restricted to a Liouville operator space whose dimension scales only as N^{2}, leading to a slow growth of multispin correlations. Even though longrange couplings are present in the real system, we find excellent agreement between the analytical predictions and ...
Generic Phases Of CrossLinked Active Gels: Relaxation, Oscillation And Contractility, Shiladitya Banerjee, Tanniemola B. Liverpool, M. C. Marchetti
Generic Phases Of CrossLinked Active Gels: Relaxation, Oscillation And Contractility, Shiladitya Banerjee, Tanniemola B. Liverpool, M. C. Marchetti
Physics
We study analytically and numerically a generic continuum model of an isotropic active solid with internal stresses generated by nonequilibrium `active' mechanochemical reactions. Our analysis shows that the gel can be tuned through three classes of dynamical states by increasing motor activity: a constant unstrained state of homogeneous density, a state where the local density exhibits sustained oscillations, and a steadystate which is spontaneously contracted, with a uniform mean density.