Spin gaps in coupled [ital t]-[ital J] ladders

Journal Article · Thu Sep 01 04:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.6511· OSTI ID:7071429

Poilblanc, D ^[1]; Tsunetsugu, H ^[2]; Rice, T M ^[3]

---

1. Laboratoire de Physique Quantique, Universite Paul Sabatier, 31062 Toulouse (France)
2. Theoretische Physik, ETH-Hoenggerberg, 8093 Zuerich (Switzerland) and Interdisziplinaeres Projektzentrum fuer Supercomputing, ETH-Zentrum, 8092 Zuerich (Switzerland)
3. Theoretische Physik, ETH-Hoenggerberg, 8093 Zuerich (Switzerland)

Spin gaps in coupled [ital t]-[ital J] ladders are investigated by exact diagonalization of small clusters up to 4[times]8 sites. At half-filling, the numerical results for the triplet excitation spectrum are in very good agreement with a second-order perturbation expansion in terms of small interladder and intraladder exchange couplings between rungs ([ital J]/[ital J][prime][lt]0.25). The band of local triplet excitations moving coherently along the ladder (with momenta close to [pi]) is split by the interladder coupling. For intermediate couplings, finite-size scaling is used to estimate the spin gap. In the isotropic infinite four-chain system (two coupled ladders) we find a spin gap of 0.245[ital J], roughly half of the single-ladder spin gap. When the system is hole doped, bonding and antibonding bound pairs of holes can propagate coherently along the chains and the spin gap remains finite.

• OSTI ID: 7071429
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 50:9; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

665411* -- Basic Superconductivity Studies-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANTIFERROMAGNETIC MATERIALS
CHAINS
CORRELATIONS
CRYSTAL DOPING
CRYSTAL MODELS
ELECTRON CORRELATION
ENERGY-LEVEL TRANSITIONS
EXCHANGE INTERACTIONS
EXCITATION
HAMILTONIANS
HEISENBERG MODEL
HIGH-TC SUPERCONDUCTORS
HOLES
HUBBARD MODEL
INTERACTIONS
MAGNETIC MATERIALS
MATERIALS
MATHEMATICAL MODELS
MATHEMATICAL OPERATORS
MULTIPLETS
QUANTUM OPERATORS
SCALING LAWS
SUPERCONDUCTORS
TRIPLETS