Phys. Rev. B 50, 10048 - 10062 (1994)

Exact spectra, spin susceptibilities, and order parameter of the quantum Heisenberg antiferromagnet on the triangular lattice

Download: Page Images , PDF (2629 kB) , Figure Images, or Buy this Article (Use Article Pack) Export: BibTeX or EndNote (RIS)

B. Bernu
Laboratoire de Physique Théorique des Liquides, CNRS URA 765, Université Pierre et Marie Curie, Boîte Postale 121, 4 Place Jussieu, 75252 Paris Cedex, France

P. Lecheminant
Laboratoire de Physique Théorique des Liquides, CNRS URA 765 Université Pierre et Marie Curie, Boîte Postale 121, 4 Place Jussieu, 75252 Paris Cedex, France
Groupe de Physique Statistique, Université de Cergy-Pontoise, 95806 Cergy-Pontoise Cedex, France

C. Lhuillier
Laboratoire de Physique Théorique des Liquides, CNRS URA 765 Université Pierre et Marie Curie, Boîte Postale 121, 4 Place Jussieu, 75252 Paris Cedex, France

L. Pierre
Batiment G, Université Paris-X, Nanterre, 92001 Nanterre Cedex, France

Received 18 May 1994

Exact spectra of periodic samples are computed up to N=36. Evidence of an extensive set of low-lying levels, lower than the softest magnons, is exhibited. These low-lying quantum states are degenerated in the thermodynamic limit; their symmetries and dynamics as well as their finite-size scaling are strong arguments in favor of Néel order. It is shown that the Néel order parameter agrees with first-order spin-wave calculations. A simple explanation of the low-energy dynamics is given as well as the numerical determinations of the energies, order parameter, and spin susceptibilities of the studied samples. It is shown how suitable boundary conditions, which do not frustrate Néel order, allow the study of samples with N=3p+1 spins. A thorough study of these situations is done in parallel with the more conventional case N=3p.


©1994 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevB.50.10048
DOI: 10.1103/PhysRevB.50.10048
PACS: 75.10.Jm, 75.40.Mg

[ Abstract  |  Previous article  |  Next article  |  Issue 14 ]