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Full-Text Articles in Physics
Full Dyon Excitation Spectrum In Extended Levin-Wen Models, Yuting Hu, Alexandra Tebbs, Yong-Shi Wu
Full Dyon Excitation Spectrum In Extended Levin-Wen Models, Yuting Hu, Alexandra Tebbs, Yong-Shi Wu
Mathematics and Statistics Faculty Publications
In Levin-Wen (LW) models, a wide class of exactly solvable discrete models, for two-dimensional topological phases, it is relatively easy to describe only single-fluxon excitations, but not the charge and dyonic as well as many-fluxon excitations. To incorporate charged and dyonic excitations in (doubled) topological phases, an extension of the LW models is proposed in this paper. We first enlarge the Hilbert space with adding a tail on one of the edges of each trivalent vertex to describe the internal charge degrees of freedom at the vertex. Then, we study the full dyon spectrum of the extended LW models, including …
Reconstructions At The Interface In Complex Oxide Heterostructures With Strongly Correlated Electrons, Benjamin Gray
Reconstructions At The Interface In Complex Oxide Heterostructures With Strongly Correlated Electrons, Benjamin Gray
Graduate Theses and Dissertations
Strongly correlated oxides exhibit a rich spectrum of closely competing orders near the localized-itinerant Mott insulator transition leaving their ground states ripe with instabilities susceptible to small perturbations such as lattice distortions, variation in stoichiometry, magnetic and electric fields, etc. As the field of interfacial engineering has matured, these underlying instabilities in the electronic structure of correlated oxides continue to be leveraged to manipulate existing phases or search for emergent ones. The central theme is matching materials across the interface with disparate physical, chemical, electronic, or magnetic structure to harness interfacial reconstructions in the strongly coupled charge, spin, orbital, and …
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
Dartmouth Scholarship
We further investigate a class of time-reversal-invariant two-band s-wave 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 time-reversal-invariant momentum modes. We show how, in the presence of time-reversal symmetry, Z2 invariants that distinguish between trivial and nontrivial quantum phases can be constructed by considering only one of the Kramers’ sectors …
Numerical Study Of The Transition Metal Oxides And The Transport Properties Of Iron Pnictides, Shuhua Liang
Numerical Study Of The Transition Metal Oxides And The Transport Properties Of Iron Pnictides, Shuhua Liang
Doctoral Dissertations
Strongly correlated materials such as the manganites and iron pnictides are studied here with several computational techniques. Both types of materials contain transition metals. Thus, our computational models are based on the double exchange mechanism, the super exchange mechanism and the crystal field theory to describe the d electrons. In manganites, we focus on its multiferroic properties induced by the Dzyaloshinskii-Moriya interaction. In the BiFeO3 , we use classical Monte Carlo simulations to study the magnetic critical transition transition. In iron pnictides, we study the interplay between the Fermi surface orbital order and the ground state magnetic order.
A Spin-Polarized Scheme For Obtaining Quasi-Particle Energies Within The Density Functional Theory, B. Barbiellini, A. Bansil
A Spin-Polarized Scheme For Obtaining Quasi-Particle Energies Within The Density Functional Theory, B. Barbiellini, A. Bansil
Bernardo Barbiellini
We discuss an efficient scheme for obtaining spin-polarized quasi-particle excitation energies within the general framework of the density functional theory (DFT). Our approach is to correct the DFT eigenvalues via the electrostatic energy of a majority or minority spin electron resulting from its interaction with the associated exchange and correlation holes by using appropriate spin-resolved pair correlation functions. A version of the method for treating systems with localized orbitals, including the case of partially filled metallic bands, is considered. Illustrative results on Cu are presented.
Direct Observation Of Localization Of The Minority-Spin-Band 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 Minority-Spin-Band 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
Two-dimensional spin-uncompensated 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 de-twinning 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.
Compton Scattering Beyond The Impulse Approximation, I. G. Kaplan, B. Barbiellini, A. Bansil
Compton Scattering Beyond The Impulse Approximation, I. G. Kaplan, B. Barbiellini, A. Bansil
Bernardo Barbiellini
We treat the non-relativistic Compton scattering process in which an incoming photon scatters from an N-electron many-body state to yield an outgoing photon and a recoil electron, without invoking the commonly used frameworks of either the impulse approximation (IA) or the independent particle model (IPM). An expression for the associated triple differential scattering cross section is obtained in terms of Dyson orbitals, which give the overlap amplitudes between the N-electron initial state and the (N-1) electron singly ionized quantum states of the target. We show how in the high energy transfer regime, one can recover from our general formalism the …
Effect Of Hole Doping On The Electronic Structure Of Tl2201, S. Sahrakorpi, Hsin Lin, R. S. Markiewicz, A. Bansil
Effect Of Hole Doping On The Electronic Structure Of Tl2201, S. Sahrakorpi, Hsin Lin, R. S. Markiewicz, A. Bansil
Hsin Lin
We discuss doping dependencies of the electronic structure and Fermi surface of the monolayer Tl$_{2-x}$Cu$_x$Ba$_2$CuO$_{6+\delta}$ (Tl2201). The TlO bands are found to be particularly sensitive to doping in that these bands rapidly move to higher energies as holes are added into the system. Such doping effects beyond the rigid band picture should be taken into account in analyzing and modeling the electronic spectra of the cuprates.
Direct Observation Of Localization Of The Minority-Spin-Band 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 Minority-Spin-Band Electrons In Magnetite Below The Verwey Temperature, Hisao Kobayashi, Toshihiro Nagao, Masayoshi Itou, Sakae Todo, Bernardo Barbiellini, Peter E. Mijnarends, Arun Bansil, Nobuhiko Sakai
Arun Bansil
Two-dimensional spin-uncompensated 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 de-twinning 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.
A Spin-Polarized Scheme For Obtaining Quasi-Particle Energies Within The Density Functional Theory, B. Barbiellini, A. Bansil
A Spin-Polarized Scheme For Obtaining Quasi-Particle Energies Within The Density Functional Theory, B. Barbiellini, A. Bansil
Arun Bansil
We discuss an efficient scheme for obtaining spin-polarized quasi-particle excitation energies within the general framework of the density functional theory (DFT). Our approach is to correct the DFT eigenvalues via the electrostatic energy of a majority or minority spin electron resulting from its interaction with the associated exchange and correlation holes by using appropriate spin-resolved pair correlation functions. A version of the method for treating systems with localized orbitals, including the case of partially filled metallic bands, is considered. Illustrative results on Cu are presented.
Compton Scattering Beyond The Impulse Approximation, I. G. Kaplan, B. Barbiellini, A. Bansil
Compton Scattering Beyond The Impulse Approximation, I. G. Kaplan, B. Barbiellini, A. Bansil
Arun Bansil
We treat the non-relativistic Compton scattering process in which an incoming photon scatters from an N-electron many-body state to yield an outgoing photon and a recoil electron, without invoking the commonly used frameworks of either the impulse approximation (IA) or the independent particle model (IPM). An expression for the associated triple differential scattering cross section is obtained in terms of Dyson orbitals, which give the overlap amplitudes between the N-electron initial state and the (N-1) electron singly ionized quantum states of the target. We show how in the high energy transfer regime, one can recover from our general formalism the …
Effect Of Hole Doping On The Electronic Structure Of Tl2201, S. Sahrakorpi, Hsin Lin, R. S. Markiewicz, A. Bansil
Effect Of Hole Doping On The Electronic Structure Of Tl2201, S. Sahrakorpi, Hsin Lin, R. S. Markiewicz, A. Bansil
Robert Markiewicz
We discuss doping dependencies of the electronic structure and Fermi surface of the monolayer Tl$_{2-x}$Cu$_x$Ba$_2$CuO$_{6+\delta}$ (Tl2201). The TlO bands are found to be particularly sensitive to doping in that these bands rapidly move to higher energies as holes are added into the system. Such doping effects beyond the rigid band picture should be taken into account in analyzing and modeling the electronic spectra of the cuprates.
Conductivity Of A Spin-Polarized Two-Dimensional Electron Liquid In The Ballistic Regime, A. A. Shashkin, E. V. Deviatov, V. T. Dolgopolov, A. A. Kapustin, S. Anissimova, A. Venkatesan, S. V. Kravchenko, T. M. Klapwijk
Conductivity Of A Spin-Polarized Two-Dimensional Electron Liquid In The Ballistic Regime, A. A. Shashkin, E. V. Deviatov, V. T. Dolgopolov, A. A. Kapustin, S. Anissimova, A. Venkatesan, S. V. Kravchenko, T. M. Klapwijk
Sergey Kravchenko
In the ballistic regime, the metallic temperature dependence of the conductivity in a twodimensional electron system in silicon is found to change non-monotonically with the degree of spin polarization. In particular, it fades away just before the onset of complete spin polarization but reappears again in the fully spin-polarized state, being, however, suppressed relative to the zero-field case. Analysis of the degree of the suppression allows one to distinguish between the screening and the interaction-based theories.
A Metal-Insulator Transition In 2d: Established Facts And Open Questions, S. V. Kravchenko, M. P. Sarachik
A Metal-Insulator Transition In 2d: Established Facts And Open Questions, S. V. Kravchenko, M. P. Sarachik
Sergey Kravchenko
The discovery of a metallic state and a metal-insulator transition (MIT) in two-dimensional (2D) electron systems challenges one of the most influential paradigms of modern mesoscopic physics, namely, that "there is no true metallic behavior in two dimensions". However, this conclusion was drawn for systems of noninteracting or weakly interacting carriers, while in all 2D systems exhibiting the metal-insulator transition, the interaction energy greatly exceeds all other energy scales. We review the main experimental findings and show that, although significant progress has been achieved in our understanding of the MIT in 2D, many open questions remain.
"Forbidden" Transitions Between Quantum Hall And Insulating Phases In P-Sige Heterostructures, M. R. Sakr, Maryam Rahimi, S. V. Kravchenko, P. T. Coleridge, R. L. Williams, J. Lapointe
"Forbidden" Transitions Between Quantum Hall And Insulating Phases In P-Sige Heterostructures, M. R. Sakr, Maryam Rahimi, S. V. Kravchenko, P. T. Coleridge, R. L. Williams, J. Lapointe
Sergey Kravchenko
We show that in dilute metallic p-SiGe heterostructures, magnetic field can cause multiple quantum Hall-insulator-quantum Hall transitions. The insulating states are observed between quantum Hall states with filling factors = 1 and 2 and, for the first time, between = 2 and 3 and between = 4 and 6. The latter are in contradiction with the original global phase diagram for the quantum Hall effect. We suggest that the application of a (perpendicular) magnetic field induces insulating behaviour in metallic p-SiGe heterostructures in the same way as in Si MOSFETs. This insulator is then in competition with, and interrupted by, …
Comment On "Theory Of Metal-Insulator Transitions In Gated Semiconductors", S. V. Kravchenko, M. P. Sarachik, D. Simonian
Comment On "Theory Of Metal-Insulator Transitions In Gated Semiconductors", S. V. Kravchenko, M. P. Sarachik, D. Simonian
Sergey Kravchenko
No abstract provided.
Absorption Of Nuclear Gamma Radiation By Heavy Electrons On Metallic Hydride Surfaces, A. Widom, L. Larsen
Absorption Of Nuclear Gamma Radiation By Heavy Electrons On Metallic Hydride Surfaces, A. Widom, L. Larsen
Allan Widom
Low energy nuclear reactions in the neighborhood of metallic hydride surfaces may be induced by ultra-low momentum neutrons. Heavy electrons are absorbed by protons or deuterons producing ultra low momentum neutrons and neutrinos. The required electron mass renormalization is provided by the interaction between surface electron plasma oscillations and surface proton oscillations. The resulting neutron catalyzed low energy nuclear reactions emit copious prompt gamma radiation. The heavy electrons which induce the initially produced neutrons also strongly absorb the prompt nuclear gamma radiation, re-emitting soft photons. Nuclear hard photon radiation away from the metallic hydride surfaces is thereby strongly suppressed.