Disorder and impurities in hubbard-antiferromagnets

  • M. Ulmke
  • P. J. H. Denteneer
  • V. Janiš
  • R. T. Scalettar
  • A. Singh
  • D. Vollhardt
  • G. T. Zimanyi
Conference paper
Part of the Advances in Solid State Physics book series (ASSP, volume 38)

Abstract

We study the influence of disorder and randomly distributed impurities on the properties of correlated antiferromagnets. To this end the Hubbard model with (i) random potentials, (ii) random hopping elements, and (iii) randomly distributed values of interaction is treated using quantum Monte Carlo and dynamical mean-field theory. In cases (i) and (iii) weak disorder can lead to an enhancement of antiferromagnetic (AF) order: in case (i) by a disorder-induced delocalization, in case (iii) by binding of free carriers at the impurities. For strong disorder or large impurity concentration antiferromagnetism is eventually destroyed. Random hopping leaves the local moment stable but AF order is suppressed by local singlet formation. Random potentials induce impurity states within the charge gap until it eventually closes. Impurities with weak interaction values shift the Hubbard gap to a density off half-filling. In both cases an antiferromagnetic phase without charge gap is observed.

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Copyright information

© Friedr. Vieweg & Sohn Verlagsgesellschaft mbH 1999

Authors and Affiliations

  • M. Ulmke
    • 1
  • P. J. H. Denteneer
    • 2
  • V. Janiš
    • 3
  • R. T. Scalettar
    • 4
  • A. Singh
    • 1
  • D. Vollhardt
    • 1
  • G. T. Zimanyi
    • 4
  1. 1.Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Insitut für PhysikUniversität AugsburgAugsburgGermany
  2. 2.Lorentz Institute for Theoretical PhysicsUniversity of LeidenLeidenThe Netherlands
  3. 3.Institute of PhysicsAcademy of Sciences of the Czech RepublikPraha 8Czech Republik
  4. 4.Department of PhysicsUniversity of CaliforniaDavisUSA
  5. 5.Department of PhysicsIndian Institute of TechnologyKanpur

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