Phase separation instabilities in two-dimensional Betts clusters: exact results

ORAL

Abstract

The energy eigenvalues and eigenstates of the Hubbard model with nearest and next nearest neighbor hopping are calculated by exact diagonalization technique and Lanczos algorithm by exploiting the square symmetry of isotropic Betts square (cells) - clusters with periodic boundary conditions. The electron pairing instabilities, order parameters and quantum critical points (at one hole away from half filling) are evaluated by monitoring the charge and spin pairing gaps in a wide range of interaction strengths which show level crossings in the ground state and corresponding crossovers at finite temperatures. The calculated critical behavior of the energy gap in optimized 8-site square symmetry lattice structures display universal features consistent with the exact results obtained for elementary bipartite square geometry [A. N. Kocharian et al., Phys. Rev. B 78, 075431 (2008)]. The effects of the next nearest neighbor hopping and temperature on these electron instabilities are also considered. Behavior of electrons in contrasting bipartite and non-bipartite two- and three-dimensional topologies display a number of inhomogeneous, paired and non-paired nanoscale phases seen in high T$_c$ cuprates, manganites.

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Authors

  • Armen N. Kocharian

    California State University, Los Angeles

  • Andreas Bill

    Photonics CoE, Sciprint.org, LLNL, OSU, Imperial College London, General Atomis, UCSD, University of Milan, Instituto Superior Technico, University of Alberta, US Dept. of Agriculture, Agriculture Research Service, Parlier, CA, Dept. of Chemistry, California State University, Fresno, Dept. of Physics, California State University, Fresno, Weizmann Institute of Science, Stanford University, University of Connecticut, Storrs, UC Irvine, University of Missouri-Kansas City, California Institute of Technology, Ulm University, TU Darmstadt, UC Berkeley, GSFC, University of Regenberg, Germany, Lawrence Livermore National Laboratory, Clarendon Laboratory, Oxford, University of California, Los Angeles, Gesellschaft fuer Schwerionenforschung (GSI), Laboratoire pour l'Utilisation des Lasers Intenses, PSFC, MIT, University of California, Santa Barbara, Process Measurements Division, National Institute of Standards and Technology, Gaithersburg, MD, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, Division of Chemistry, California Institute of Technology, Pasadena, CA, Department of Physics, Fars Science and Research Center, Islamic Azad University, Texas A\&M University-Commerce, California State University, Long Beach, Materials Department, University of California Santa Barbara

  • Andreas Bill

    Photonics CoE, Sciprint.org, LLNL, OSU, Imperial College London, General Atomis, UCSD, University of Milan, Instituto Superior Technico, University of Alberta, US Dept. of Agriculture, Agriculture Research Service, Parlier, CA, Dept. of Chemistry, California State University, Fresno, Dept. of Physics, California State University, Fresno, Weizmann Institute of Science, Stanford University, University of Connecticut, Storrs, UC Irvine, University of Missouri-Kansas City, California Institute of Technology, Ulm University, TU Darmstadt, UC Berkeley, GSFC, University of Regenberg, Germany, Lawrence Livermore National Laboratory, Clarendon Laboratory, Oxford, University of California, Los Angeles, Gesellschaft fuer Schwerionenforschung (GSI), Laboratoire pour l'Utilisation des Lasers Intenses, PSFC, MIT, University of California, Santa Barbara, Process Measurements Division, National Institute of Standards and Technology, Gaithersburg, MD, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, Division of Chemistry, California Institute of Technology, Pasadena, CA, Department of Physics, Fars Science and Research Center, Islamic Azad University, Texas A\&M University-Commerce, California State University, Long Beach, Materials Department, University of California Santa Barbara