Infinite-range Heisenberg model and high-temperature superconductivity

Journal Article · Mon Nov 01 00:00:00 EST 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.48.13002· OSTI ID:5967292

Tahir-Kheli, J; Goddard, III, W A ^[1]

---

1. Materials and Molecular Simulation Center, Beckman Institute 139-74, California Institute of Technology, Pasadena, California 91125 (United States)

A strongly coupled variational wave function, the doublet spin-projected Neel state (DSPN), is proposed for oxygen holes in three-band models of high-temperature superconductors. This wave function has the three-spin system of the oxygen hole plus the two neighboring copper atoms coupled in a spin-1/2 doublet. The copper spins in the neighborhood of a hole are in an eigenstate of the infinite-range Heisenberg antiferromagnet (SPN state). The doublet three-spin magnetic polaron or hopping polaron (HP) is stabilized by the hopping terms [ital t][sub [sigma]] and [ital t][sub [tau]], rather than by the copper-oxygen antiferromagnetic coupling [ital J][sub pd]. Although, the HP has a large projection onto the Emery ([ital D][sub [ital g]]) polaron, a non-negligible amount of doublet-[ital u] ([ital D][sub [ital u]]) character is [ital required] for optimal hopping stabilization. This is due to [ital J][sub [ital d][ital d]], the copper-copper antiferromagnetic coupling. For the copper spins near an oxygen hole, the copper-copper antiferromagnetic coupling can be considered to be almost infinite ranged, since the copper-spin-correlation length in the superconducting phase (0.06--0.25 holes per in-plane copper) is approximately equal to the mean separation of the holes (between 2 and 4 lattice spacings). The general DSPN wave function is constructed for the motion of a single quasiparticle in an antiferromagnetic background. The SPN state allows simple calculations of various couplings of the oxygen hole with the copper spins. The energy minimum is found at symmetry ([pi]/2,[pi]/2) and the bandwidth scales with [ital J][sub [ital d][ital d]]. These results are in agreement with exact computations on a lattice. The coupling of the quasiparticles leads to an attraction of holes and its magnitude is estimated.

• OSTI ID: 5967292
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 48:17; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
HIGH-TC SUPERCONDUCTORS
HEISENBERG MODEL
ANTIFERROMAGNETISM
HOLES
VARIATIONAL METHODS
WAVE FUNCTIONS
CALCULATION METHODS
CRYSTAL MODELS
FUNCTIONS
MAGNETISM
MATHEMATICAL MODELS
SUPERCONDUCTORS
665411* - Basic Superconductivity Studies- (1992-)