Doped two orbital chains with strong Hund's rule couplings - Ferromagnetism, spin gap, singlet and triplet pairings

Beat Ammon, Masatoshi Imada

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Different models for doping of two-orbital chains with mobile S = 1/2 fermions and strong, ferromagnetic (FM) Hund's rule couplings stabilizing the S = 1 spins are investigated by density matrix renormalization group (DMRG) methods. The competition between antiferromagnetic (AF) and FM order leads to a rich phase diagram with a narrow FM region for weak AF couplings and strongly enhanced triplet pairing correlations. Without a level difference between the orbitals, the spin gap persists upon doping, whereas gapless spin excitations are generated by interactions among itinerant polarons in the presence of a level difference. In the charge sector we find dominant singlet pairing correlations without a level difference, whereas upon the inclusion of a Coulomb repulsion between the orbitals or with a level difference, charge density-wave (CDW) correlations decay slowest. The string correlation functions remain finite upon doping for all models.

Original languageEnglish
Pages (from-to)547-557
Number of pages11
Journaljournal of the physical society of japan
Volume70
Issue number2
DOIs
Publication statusPublished - 2001 Feb 1

Keywords

  • Ferromagnetism
  • Mott-Hubbard transition
  • Spin-1 systems
  • String order
  • Superconductivity
  • Triplet superconductivity

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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