Superconductivity in a narrow-band system with intersite electron pairing in two dimensions. II. Effects of nearest-neighbor exchange and correlated hopping

Journal Article · Thu Jun 01 04:00:00 EDT 1989 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.39.11653· OSTI ID:6136719

Micnas, R; Ranninger, J; Robaszkiewicz, S

Our previous mean-field study concerning superconducting pairings in the extended Hubbard model with on-site repulsive and intersite attractive interaction and arbitrary electron density is extended to include the effects of nearest-neighbor exchange (/ital J/) and correlated hopping (/ital K/) interaction. Detailed numerical analysis of /ital s/-, /ital p/-, and /ital d/-wave pairing solutions is performed for the two-dimensional square lattice with nearest- (/ital t/) and next-nearest- (/ital t//sub 2/) neighbor hopping, and the resulting mutual stability phase diagrams are given as a function of band filling and the interaction parameters. Antiferroamgnetic exchange can enhance both the /ital d/-wave and the extended /ital s/-wave pairing. If it prevails over the repulsive intersite density-density interaction, such a term can be a leading mechanism for superconductivity. However, its effects strongly depend on the band filling and the /ital t//sub 2//t ratio, giving in particular for /ital t//sub 2/=0 /ital s/-wave (/ital d/-wave) pairing as most favorable in the low (high) density limit, but increasing /ital t//sub 2/ can even reverse this tendency. The correlated hopping term which breaks the electron-hole symmetry affects /ital s/-wave pairing mostly. A condensation transition (phase separation), possible in the presence of the attractive density-density interaction, is also analyzed within the random-phase approximation, and stability conditions of such an electron droplet phase with respect to other types of ordering are determined as a function of the band filling for the two-dimensional square lattice.

• Research Organization: Institute of Physics, A. Mickiewicz University, PL-60-769, Poznan, Poland(PL); Centre National de la Recherche Scientifique, Centre de Recherches sur les Tres Basses Temperatures, Boite Postale No. 166X, 348042 Grenoble, France; Institut Laue-Langevin, Boite Postale No. 166X, 38042 Grenoble, France
• OSTI ID: 6136719
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 39:16; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

656100* -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANTIFERROMAGNETISM
BAND THEORY
DIAGRAMS
ELECTRONIC STRUCTURE
INTERACTIONS
MAGNETISM
NUMERICAL SOLUTION
PAIRING INTERACTIONS
PHASE DIAGRAMS
SUPERCONDUCTORS
TWO-DIMENSIONAL CALCULATIONS