Paired-magnon analysis of quantum antiferromagnets

Journal Article · Fri Sep 01 00:00:00 EDT 1989 · Physical Review (Section) B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.40.4904· OSTI ID:5590084

Manousakis, E ^[1]

---

1. Department of Physics, Center for Materials Research and Technology Supercomputer Computations Research Institute, Florida State University, Tallahassee, Florida 32306 (US)

We study the spin-1/2 Heisenberg antiferromagnet on an infinite square lattice. The calculational scheme known as paired-phonon analysis'' developed for strongly correlated quantum fluids is extended to a paired-magnon analysis'' to study quantum antiferromagnets. We define a complete and orthonormal set of multimagnon states and calculate the matrix elements of the Hamiltonian using a separability approximation. Our results obtained by diagonalizing the Hamiltonian matrix analytically are very similar to those obtained in spin-wave theory. We obtain {minus}0.3290, for the ground-state energy per bond in units of the antiferromagnetic coupling and 0.303 for the ground-state staggered magnetization. These results compare well with the best-known estimates {minus}0.334{plus minus}0.001 and 0.313, respectively. We derive the analytic form of the ground-state wave function in this approximation and find it to be of the same form as that assumed by Marshall in his variational studies.. The zero-point motion of long-wavelength excitations (spin waves) in the model, however, reflects a long-range tail in our wave function. We discuss the separability approximation by giving quantitative arguments which justify its validity.

• OSTI ID: 5590084
• Journal Information: Physical Review (Section) B: Condensed Matter; (USA), Vol. 40:7; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANTIFERROMAGNETIC MATERIALS
HEISENBERG MODEL
GROUND STATES
HAMILTONIANS
MAGNONS
WAVE FUNCTIONS
CRYSTAL MODELS
ENERGY LEVELS
FUNCTIONS
MAGNETIC MATERIALS
MATERIALS
MATHEMATICAL MODELS
MATHEMATICAL OPERATORS
QUANTUM OPERATORS
QUASI PARTICLES
656002* - Condensed Matter Physics- General Techniques in Condensed Matter- (1987-)