Magnetic and metal-insulator transitions through bandwidth control in two-dimensional Hubbard models with nearest and next-nearest neighbor transfers

Tsuyoshi Kashima, Masatoshi Imada

Research output: Contribution to journalArticle

82 Citations (Scopus)

Abstract

Numerical studies on Mott transitions caused by the control of the ratio between bandwidth and electron-electron interaction (U) are reported. By using the recently proposed path-integral renormalization group (PIRG) algorithm, physical properties near the transitions in the ground state of two-dimensional half-filled models with the nearest and the next-nearest neighbor transfers (-t and t′, respectively) are studied as a prototype of geometrically frustrated system. The nature of the bandwidth-control transitions shows sharp contrast with that of the filling-control transitions: First, the metal-insulator and magnetic transitions are separated each other and the metal-insulator (MI) transition occurs at smaller U, although the both transition interactions U increase with increasing t′. Both transitions do not contradict the first-order transitions for smaller t′/t while the MI transitions become continuous type accompanied by emergence of unusual metallic phase near the transition for large t′/t. A nonmagnetic insulator phase is stabilized between MI and AF transitions. The region of the nonmagnetic insulator becomes wider with increasing t′/t. The phase diagram naturally connects two qualitatively different limits, namely the Hartree-Fock results at small t′/t and speculations in the strong coupling Heisenberg limit.

Original languageEnglish
Pages (from-to)3052-3067
Number of pages16
JournalJournal of the Physical Society of Japan
Volume70
Issue number10
DOIs
Publication statusPublished - 2001 Oct 1
Externally publishedYes

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two dimensional models
insulators
bandwidth
metals
electron scattering
physical properties
prototypes
phase diagrams

Keywords

  • Geometrical frustration
  • Hubbard model
  • J -j model
  • Magnetic transition
  • Metal-insulator transition
  • Mott transition
  • Quantum phase transition
  • Quantum simulation
  • Spin liquid
  • Strongly correlated electron

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

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abstract = "Numerical studies on Mott transitions caused by the control of the ratio between bandwidth and electron-electron interaction (U) are reported. By using the recently proposed path-integral renormalization group (PIRG) algorithm, physical properties near the transitions in the ground state of two-dimensional half-filled models with the nearest and the next-nearest neighbor transfers (-t and t′, respectively) are studied as a prototype of geometrically frustrated system. The nature of the bandwidth-control transitions shows sharp contrast with that of the filling-control transitions: First, the metal-insulator and magnetic transitions are separated each other and the metal-insulator (MI) transition occurs at smaller U, although the both transition interactions U increase with increasing t′. Both transitions do not contradict the first-order transitions for smaller t′/t while the MI transitions become continuous type accompanied by emergence of unusual metallic phase near the transition for large t′/t. A nonmagnetic insulator phase is stabilized between MI and AF transitions. The region of the nonmagnetic insulator becomes wider with increasing t′/t. The phase diagram naturally connects two qualitatively different limits, namely the Hartree-Fock results at small t′/t and speculations in the strong coupling Heisenberg limit.",
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