The Resonating-Valence-Bond Ground State of Li Nanoclusters (2008)
Nissenbaum, D., Spanu, L., Attaccalite, C., Barbiellini, B., Bansil, A.
We have performed Diffusion Quantum Monte Carlo simulations of Li clusters showing that Resonating-Valence-Bond (RVB) pairing correlations between electrons provide a substantial contribution to the...
Magnetic mechanism of quasiparticle pairing in hole-doped cuprate superconductors (2008)
We have computed alpha^2F's for the hole-doped cuprates within the framework of the one-band Hubbard model, where the full magnetic response of the system is treated properly. The d-wave pairing...
Appearance of Universal Metallic Dispersion in a Doped Mott Insulator (2008)
Sahrakorpi, S., Markiewicz, R. S., Lin, Hsin, Lindroos, M., Zhou, X. J., Yoshida, T., ...
We have investigated the dispersion renormalization $Z_{disp}$ in La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) over the wide doping range of $x=0.03-0.30$, for binding energies extending to several hundred meV's....
Strong correlation effects and optical conductivity in electron doped cuprates (2008)
Das, Tanmoy, Markiewicz, R. S., Bansil, A.
We demonstrate that most features ascribed to strong correlation effects in various spectroscopies of the cuprates are captured by a calculation of the self-energy incorporating effects of spin and...
Nieminen, Jouko, Lin, Hsin, Markiewicz, R. S., Bansil, A.
We have developed a material specific theoretical framework for modelling scanning tunneling spectroscopy (STS) of high temperature superconducting materials in the normal as well as the...
Resonant Inelastic X-ray Scattering (RIXS) Spectra for Ladder Cuprates (2008)
Al-Sawai, W., Markiewicz, R. S., Hasan, M. Z., Bansil, A.
The ladder compound Sr$_{14}$Cu$_{24}$O$_{41}$ is of interest both as a quasi-one-dimensional analog of the superconducting cuprates and as a superconductor in its own right when Sr is substituted by...
Das, Tanmoy, Markiewicz, R. S., Bansil, A.
We discuss evolution of the Fermi surface (FS) topology with doping in electron doped cuprates within the framework of a one-band Hubbard Hamiltonian, where antiferromagnetism and superconductivity...
A competing order scenario of two-gap behavior in hole doped cuprates (2007)
Das, Tanmoy, Markiewicz, R. S., Bansil, A.
Angle-dependent studies of the gap function provide evidence for the coexistence of two distinct gaps in hole doped cuprates, where the gap near the nodal direction scales with the superconducting...
Nissenbaum, D., Barbiellini, B., Bansil, A.
We have investigated decorrelation of samples in Quantum Monte Carlo (QMC) ground-state energy calculations for large Li and H$_{2}$O nanoclusters. Binning data as a way of eliminating statistical...
Positron studies of surfaces, structure and electronic properties of nanocrystals (2007)
Eijt, S. W. H., Barbiellini, B., Houtepen, A. J., Vanmaekelbergh, D., Mijnarends, P. E., Bansil, A.
A brief review is given of recent positron studies of metal and semiconductor nanocrystals. The prospects offered by positron annihilation as a sensitive method to access nanocrystal (NC) properties...
Li, Y. W., Qian, D., Wray, L., Hsieh, D., Kaga, Y., Sasagawa, T., ...
Momentum resolved inelastic resonant x-ray scattering is used to map the evolution of charge excitations over a large range of energies, momenta and doping levels in the electron doped Mott insulator...
Das, Tanmoy, Markiewicz, R. S., Bansil, A.
We have investigated the doping dependence of the penetration depth vs. temperature in electron doped Pr$_{2-x}$Ce$_x$CuO$_{4-\delta}$ using a model which assumes the uniform coexistence of...
Li, Yinwan, Montano, P. A., Barbiellini, B., Mijnarends, P. E., Kaprzyk, S., Bansil, A.
In order to probe the magnetic ground state, we have carried out temperature dependent magnetic Compton scattering experiments on an oriented single crystal of magnetite (Fe$_3$O$_4$), together with...
Paramagnon-induced dispersion anomalies in the cuprates (2007)
Markiewicz, R. S., Sahrakorpi, S., Bansil, A.
We report the self-energy associated with RPA magnetic susceptibility in the hole-doped Bi_2Sr_2CuO_6 (Bi2201) and the electron-doped Nd_{2-x}Ce_xCuO_4 (NCCO) in the overdoped regime within the...
Dispersion anomalies induced by the low-energy plasmon in the cuprates (2007)
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...
The hierarchy of multiple many-body interaction scales in high-temperature superconductors (2006)
Meevasana, W., Zhou, X. J., Sahrakorpi, S., Lee, W. S., Yang, W. L., Tanaka, K., ...
To date, angle-resolved photoemission spectroscopy has been successful in identifying energy scales of the many-body interactions in correlated materials, focused on binding energies of up to a few...
Effect of Hole Doping on the Electronic Structure of Tl2201 (2006)
Sahrakorpi, S., Lin, Hsin, Markiewicz, R. S., Bansil, A.
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...
Das, Tanmoy, Markiewicz, R. S., Bansil, A.
Recent experiments on Pr$_{0.89}$LaCe$_{0.11}$CuO$_4$ observe an anisotropic spin-correlation gap and a nonmonotonic superconducting (SC) gap, which we analyze within the framework of a...
Anomalous electronic correlations in ground state momentum density of Al$_{97}$Li$_3$ (2006)
Kwiatkowska, J., Barbiellini, B., Kaprzyk, S., Bansil, A., Kawata, H., Shiotani, N.
We report high resolution Compton scattering measurements on an Al$_{97}$Li$_3$ disordered alloy single crystal for momentum transfer along the [100], [110] and [111] symmetry directions. The results...
How different Fermi surface maps emerge in photoemission from Bi2212 (2005)
Asensio, M. C., Avila, J., Roca, L., Tejeda, A., Gu, G. D., Lindroos, M., ...
We report angle-resolved photoemission spectra (ARPES) from the Fermi energy ($E_F$) over a large area of the ($k_x,k_y$) plane using 21.2 eV and 32 eV photons in two distinct polarizations from an...
We present a three-band Hubbard Hamiltonian and the associated Cu K-edge RIXS spectra for electron and hole doped cuprates over a wide range of energy and momentum transfers. By comparing computed...
Lin, Hsin, Sahrakorpi, S., Markiewicz, R. S., Bansil, A.
The Fermi surface (FS) of Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi2212) predicted by band theory displays Bi-related pockets around the $(\pi,0)$ point, which have never been observed experimentally....
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...
Extracting d-orbital occupancy from magnetic Compton scattering in bilayer manganites (2005)
Barbiellini, B., Mijnarends, P. E., Kaprzyk, S., Bansil, A., Li, Yinwan, Mitchell, J. F., ...
We consider the shape of the magnetic Compton profile (MCP), $J_{mag}(p_z)$, in La$_{1.2}$Sr$_{1.8}$Mn$_2$O$_7$ for momentum transfer $p_z$ along the [110] direction and the associated reciprocal...
Markiewicz, R. S., Sahrakorpi, S., Lindroos, M., Lin, Hsin, Bansil, A.
We discuss the effects of interlayer hopping and the resulting $k_z$-dispersion in the cuprates within the framework of the one-band tight binding (TB) model Hamiltonian. Specific forms of the...
Evolution of Mid-gap States and Residual 3-Dimensionality in La$_{2-x}$Sr$_x$CuO$_4$ (2005)
Sahrakorpi, S., Lindroos, M., Markiewicz, R. S., Bansil, A.
We have carried out extensive first principles doping-dependent computations of angle-resolved photoemission (ARPES) intensities in La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) over a wide range of binding...
Mijnarends, P. E., Kaprzyk, S., Barbiellini, B., Bansil, A., Li, Yinwan, Mitchell, J. F., ...
We have carried out first principles, all-electron computations of the magnetic momentum density $\rho_{mag}({\mathbf p})$ and magnetic Compton profiles (MCPs) for momentum transfer along the [100],...
Li, Yinwan, Montano, P. A., Mitchell, J. F., Barbiellini, B., Mijnarends, P. E., Kaprzyk, S., ...
We have measured temperature-dependent magnetic Compton profiles (MCPs) from a single crystal of La$_{1.2}$Sr$_{1.8}$Mn$_2$O$_7$. The MCPs, which involved the scattering of circularly polarized...
Bansil, A., Lindroos, M., Sahrakorpi, S., Markiewicz, R. S.
Angle-resolved photoemission spectroscopy (ARPES) presents significant simplications in analyzing strictly two-dimensional (2D) materials, but even the most anisotropic physical systems display some...
Electron correlations, spontaneous magnetization and momentum density in quantum dots (2004)
Bansil, A., Nissenbaum, D., Barbiellini, B., Saniz, R.
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...
Dyson Orbitals, Quasi-Particle effects and Compton scattering (2004)
Dyson orbitals play an important role in understanding quasi-particle effects in the correlated ground state of a many-particle system and are relevant for describing the Compton scattering cross...
Matrix Element and Strong Electron Correlation Effects in ARPES from Cuprates (2004)
Bansil, A., Markiewicz, R. S., Kusko, C., Lindroos, M., Sahrakorpi, S.
We discuss selected results from our recent work concerning the ARPES (angle-resolved photoemission) spectra from the cuprates. Our focus is on developing an understanding of the effects of the ARPES...
Spontaneous Magnetization and Electron Momentum Density in 3D Quantum Dots (2003)
Saniz, R., Barbiellini, B., Denison, A. B., Bansil, A.
We discuss an exactly solvable model Hamiltonian for describing the interacting electron gas in a quantum dot. Results for a spherical square well confining potential are presented. The ground state...
Compton scattering beyond the impulse approximation (2003)
Kaplan, I. G., Barbiellini, B., Bansil, A.
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...
Sahrakorpi, S., Lindroos, M., Bansil, A.
We show that the ARPES spectra for emission from the bonding as well as the antibonding Fermi surface sheet in Bi$_2$Sr$_2$CaCu$_2$O$_8$ (Bi2212) possess remarkable site selectivity properties in...
Electron momentum density in Cu0.9Al0.1 (2002)
Samsel-Czekala, M., Kontrym-Sznajd, G., Doring, G., Schulke, W., Kwiatkowska, J., Maniawski, F., ...
A reconstruction technique based on the solution of the Radon transform in terms of Jacobi polynomials is used to obtain the 3D electron momentum density rho(p) from nine high-resolution Compton...
Reconstructed Momentum Density and Fermi Surface in Cu0.9Al0.1 (2002)
Samsel-Czekala, M., Kontrym-Sznajd, G., Doring, G., Schulke, W., Kaprzyk, S., Bansil, A., ...
A reconstruction technique based on Radon transforms is used to obtain 3D electron momentum density rho(p) using nine recently measured high-resolution Compton profiles (CPs) from a Cu_{0.9}Al_{0.1}...
Quantum Critical Point in Electron-Doped Cuprates (2002)
Kusko, C., Markiewicz, R. S., Lindroos, M., Bansil, A.
We analyze doping dependent spectral intensities and Fermi surface maps obtained recently in Nd$_{2-x}$Ce$_x$CuO$_{4\pm\delta}$ (NCCO) via high resolution ARPES measurements, and show that the...
How different Fermi surface maps emerge in photoemission from Bi2212 (2001)
Asensio, M. C., Avila, J., Roca, L., Tejeda, A., Gu, G. D., Lindroos, M., ...
We report angle-resolved photoemission spectra (ARPES) from the Fermi energy ($E_F$) over a large area of the ($k_x,k_y$) plane using 21.2 eV and 32 eV photons in two distinct polarizations from an...
Lindroos, M., Sahrakorpi, S., Bansil, A.
We have carried out extensive simulations of the angle-resolved photoemission (ARPES) intensity in Bi2212 within the one-step and three-step type models using a first-principles band theory...
Matsumoto, I., Kwiatkowska, J., Maniawski, F., Itou, M., Kawata, H., Shiotani, N., ...
We present a novel technique for enhancing Fermi surface (FS) signatures in the 2D distribution obtained after the 3D momentum density in a crystal is projected along a specific direction in momentum...
Recent high resolution Compton scattering experiments clearly reveal that there are fundamental limitations to the conventional local density approximation (LDA) based description of the ground state...
How different Fermi surface maps emerge in photoemission from Bi2212 (2001)
Asensio, M. C., Avila, J., Roca, L., Tejeda, A., Gu, G. D., Lindroos, M., ...
We report angle-resolved photoemission spectra (ARPES) from the Fermi energy ($E_F$) over a large area of the ($k_x,k_y$) plane using 21.2 eV and 32 eV photons in two distinct polarizations from an...
How different Fermi surface maps emerge in photoemission from Bi2212 (2001)
Asensio, M. C., Avila, J., Roca, L., Tejeda, A., Gu, G. D., Lindroos, M., ...
We report angle-resolved photoemission spectra (ARPES) from the Fermi energy ($E_F$) over a large area of the ($k_x,k_y$) plane using 21.2 eV and 32 eV photons in two distinct polarizations from an...
A High-Resolution Compton Scattering Study of the Electron Momentum Density in Al (2000)
Ohata, T., Itou, M., Matsumoto, I., Sakurai, Y., Kawata, H., Shiotani, N., ...
We report high-resolution Compton profiles (CP's) of Al along the three principal symmetry directions at a photon energy of 59.38 keV, together with corresponding highly accurate theoretical profiles...
High-resolution Compton Scattering as a Probe of Fermiology and Electron Correlation Effects (2000)
Compton scattering is one of the few spectroscopies which directly probes the ground state momentum density in materials. Recent progress in synchrotron light sources has brought a renewed interest...
(2000) 341-344 [59] A Compton scattering study of insulating PrBa (2000)
A. Erb, B. Revaz, T. Buslaps, V. Honki Maki, E. D. Isaacs, A. Shukla, ...
bel, F. Steglich and M. Peter, Phys. Rev. B 55 (1997) 11714-11721 [49] Stochastic Gradient Approximation: An Efficient Method to Optimize Many-body Wave Functions A. Harju, B. Barbiellini, S....
High-resolution Compton scattering study of the electron momentum density in Al (2000)
Matsumoto, I., Sakurai, Y., Kawata, H., Shiotani, N., Kaprzyk, S., ...
A Fermi Surface study of Ba$_{1-x}$K$_{x}$BiO$_{3}$ (1999)
Sahrakorpi, S., Barbiellini, B., Markiewicz, R. S., Kaprzyk, S., Lindroos, M., Bansil, A.
We present all electron computations of the 3D Fermi surfaces (FS's) in Ba$_{1-x}$K$_{x}$BiO$_{3}$ for a number of different compositions based on the selfconsistent Korringa-Kohn-Rostoker...
Importance of matrix elements in the ARPES spectra of BISCO (1999)
We have carried out extensive first-principles angle-resolved photointensity (ARPES) simulations in Bi2212 wherein the photoemission process is modelled realistically by taking into account the full...
Bansil, A., Kaprzyk, S., Mijnarends, P. E., ToboĊa, J.
We present first principles charge- and spin-selfconsistent electronic structure computations on the Heusler-type disordered alloys Fe$_{3-x}$V$_{x}$X for three different metalloids X=(Si, Ga and...
CALCULATIONS OF ELECTRONIC STATES IN THE MUFFIN TIN MODEL OF A LIQUID METAL (1980)
Huisman, L., Schwartz, L., Bansil, A.
We consider the application of the effective medium approximation (EMA) to the muffin tin model of a liquid metal. The theory is applied to a model in which the atomic potentials are represented by a...
CALCULATIONS OF ELECTRONIC STATES IN THE MUFFIN TIN MODEL OF A LIQUID METAL (1980)
Huisman, L., Schwartz, L., Bansil, A.
We consider the application of the effective medium approximation (EMA) to the muffin tin model of a liquid metal. The theory is applied to a model in which the atomic potentials are represented by a...
CALCULATIONS OF ELECTRONIC STATES IN THE MUFFIN TIN MODEL OF A LIQUID METAL (1980)
Huisman, L., Schwartz, L., Bansil, A.
We consider the application of the effective medium approximation (EMA) to the muffin tin model of a liquid metal. The theory is applied to a model in which the atomic potentials are represented by a...