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

作者：Ammon B^*; Imada M

来源：Journal of the Physical Society of Japan, 2001, 70(2): 547-557.

DOI：10.1143/JPSJ.70.547

• spin-1 systems
• Mott-Hubbard transition
• superconductivity
• triplet superconductivity
• ferromagnetism
• string order

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 = I spins are investigated by density matrix renormalization group (DMRG) methods. The competition between antiferromagnet;ic (AF) and FM order leads to a rich phase digram 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 it level difference, charge density wave (CDW) correlations decay slowest. The string correlation functions remain finite upon doping for all models.

• 出版日期2001-2