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- Strongly correlated electrons (3)
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Articles 1 - 10 of 10
Full-Text Articles in Physical Sciences and Mathematics
Anomalous Electronic Correlations In The Ground State Momentum Density Of Al₉₇Li₃, J. Kwiatkowska, B. Barbiellini, S. Kaprzyk, A. Bansil, H. Kawata, N. Shiotani
Anomalous Electronic Correlations In The Ground State Momentum Density Of Al₉₇Li₃, J. Kwiatkowska, B. Barbiellini, S. Kaprzyk, A. Bansil, H. Kawata, N. Shiotani
Arun Bansil
We report high resolution Compton scattering measurements on an Al₉₇Li₃ disordered alloy single crystal for momentum transfer along the [100], [110] and [111] symmetry directions. The results are interpreted via corresponding KKR-CPA (Korringa-Kohn Rostoker coherent potential approximation) first principles computations. By comparing spectra for Al₉₇Li₃ and Al, we show that the momentum density in the alloy differs significantly from the predictions of the conventional Fermi liquid picture and that the ground state of Al is modified anomalously by the addition of Li.
Emergence Of Non-Fermi-Liquid Behavior Due To Fermi Surface Reconstruction In The Underdoped Cuprate Superconductors, Tanmoy Das, R. S. Markiewicz, A. Bansil
Emergence Of Non-Fermi-Liquid Behavior Due To Fermi Surface Reconstruction In The Underdoped Cuprate Superconductors, Tanmoy Das, R. S. Markiewicz, A. Bansil
Arun Bansil
We present an intermediate coupling scenario together with a model analytic solution where the non-Fermi-liquid behavior in the underdoped cuprates emerges through the mechanism of Fermi surface (FS) reconstruction. Even though the fluctuation spectrum remains nearly isotropic, FS reconstruction driven by a density wave order breaks the lattice symmetry and induces a strong momentum dependence in the self-energy. As the doping is reduced to half-filling, we find that quasiparticle (QP) dispersion becomes essentially unrenormalized, but in sharp contrast the QP spectral weight renormalizes to nearly zero. This opposite doping evolution of the renormalization factors for QP dispersion and spectral weight …
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 New Platform For Topological Quantum Phenomena : Topological Insulator States In Thermoelectric Heusler-Related Ternary Compounds, H. Lin, L. A. Wray, Y. Xia, S. Jia, R. J. Cava, A. Bansil, M. Z. Hasan
A New Platform For Topological Quantum Phenomena : Topological Insulator States In Thermoelectric Heusler-Related Ternary Compounds, H. Lin, L. A. Wray, Y. Xia, S. Jia, R. J. Cava, A. Bansil, M. Z. Hasan
Arun Bansil
Topological insulators realize a novel state of quantum matter that are distinguished by topological invariants of bulk band structure rather than spontaneously broken symmetries. A number of exotic quantum phenomena have been predicted to exist in multiply-connected geometries which require an enormous amount of materials flexibility. We have extended our previous search for TI materials from binary (Bi₂X₃ series, Xia et.al., Nature Phys. 5, 398 (2009)) to the thermoelectric ternary compounds. We discover that the distorted LuPtSb is the first ternary compound of the “MM´X” series harboring a 3D topological insulator state with Z₂=-1 whereas TiNiSn is trivial. We also …
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.
Decorrelation Of Samples In Quantum Monte Carlo Calculations And Scaling Of Autocorrelation Time In Li And H₂O Clusters, D. Nissenbaum, B. Barbiellini, A. Bansil
Decorrelation Of Samples In Quantum Monte Carlo Calculations And Scaling Of Autocorrelation Time In Li And H₂O Clusters, D. Nissenbaum, B. Barbiellini, A. Bansil
Arun Bansil
We have investigated decorrelation of samples in Quantum Monte Carlo (QMC) ground-state energy calculations for large Li and H₂O nanoclusters. Binning data as a way of eliminating statistical correlations, as is the common practice, is found to become increasingly impractical as the system size grows. We demonstrate nevertheless that it is possible to perform accurate energy calculations—without decorrelating samples—by exploiting the scaling of the integrated autocorrelation time τ as a function of the number of electrons in the system.
Electronic Coupling Of Colloidal Cdse Nanocrystals Monitored By Thin-Film Positron-Electron Momentum Density Methods, S. W. H. Eijt, P. E. Mijnarends, L. C. Van Schaarenburg, A. J. Houtepen, D. Vanmaekelbergh, B. Barbiellini, A. Bansil
Electronic Coupling Of Colloidal Cdse Nanocrystals Monitored By Thin-Film Positron-Electron Momentum Density Methods, S. W. H. Eijt, P. E. Mijnarends, L. C. Van Schaarenburg, A. J. Houtepen, D. Vanmaekelbergh, B. Barbiellini, A. Bansil
Arun Bansil
The effect of temperature controlled annealing on the confined valence electron states in CdSe nanocrystal arrays, deposited as thin films, was studied using two-dimensional angular correlation of annihilation radiation (2D-ACAR). A reduction in the intensity by ~35% was observed in a feature of the positron annihilation spectrum upon removal of the pyridine capping molecules above 200 degrees Celsius in a vacuum. This reduction is explained by an increased electronic interaction of the valence orbitals of neighboring nanocrystals, induced by the formation of inorganic interfaces. Partial evaporation of the nanoporous CdSe layer and additional sintering into a polycrystalline thin film was …
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 …
Electron Correlations, Spontaneous Magnetization And Momentum Density In Quantum Dots, A. Bansil, D. Nissenbaum, B. Barbiellini, R. Saniz
Electron Correlations, Spontaneous Magnetization And Momentum Density In Quantum Dots, A. Bansil, D. Nissenbaum, B. Barbiellini, R. Saniz
Arun Bansil
The magnetization of quantum dots is discussed in terms of a relatively simple but exactly solvable model Hamiltonian. The model predicts oscillations in spin polarization as a function of dot radius for a fixed electron density. These oscillations in magnetization are shown to yield distinct signature in the momentum density of the electron gas, suggesting the usefulness of momentum resolved spectroscopies for investigating the magnetization of dot systems. We also present variational quantum Monte Carlo calculations on a square dot containing 12 electrons in order to gain insight into correlation effects on the interactions between like and unlike spins in …
Dispersion Anomalies Induced By The Low-Energy Plasmon In The Cuprates, R. S. Markiewicz, A. Bansil
Dispersion Anomalies Induced By The Low-Energy Plasmon In The Cuprates, R. S. Markiewicz, A. Bansil
Arun Bansil
We discuss the characteristic effects of the electron plasmon interaction resulting from the ~ 1 eV plasmon, which is a universal feature in the cuprates. Using the framework of a one-band tight binding model, we identify signatures of this low energy plasmon in the electronic structure of metallic overdoped Bi₂212 as well as half-filled insulating SCOC. The electron-plasmon interaction is found to yield renormalizations near the Fermi energy in reasonable accord with experimental observations, and to produce dispersion anomalies at higher energies.