Low-energy singlet and triplet excitations in the spin-liquid phase of thetwo-dimensional J(1)-J(2) model

Citation
Vn. Kotov et al., Low-energy singlet and triplet excitations in the spin-liquid phase of thetwo-dimensional J(1)-J(2) model, PHYS REV B, 60(21), 1999, pp. 14613-14616
Citations number
20
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
PHYSICAL REVIEW B-CONDENSED MATTER
ISSN journal
01631829 → ACNP
Volume
60
Issue
21
Year of publication
1999
Pages
14613 - 14616
Database
ISI
SICI code
0163-1829(199912)60:21<14613:LSATEI>2.0.ZU;2-Z
Abstract
We analyze the stability of the spontaneously dimerized phase of the frustr ated Heisenberg antiferromagnet-the J(1)-J(2) model-in two dimensions. The lowest,tripler excitation, corresponding to breaking of a singlet bond, is found to be stable in the region 0.38 less than or similar to J(2)/J(1)less than or similar to 0.62. In addition we find a stable low-energy collectiv e singlet mode, which reflects the spontaneous violation of the discrete sy mmetry. The spontaneous dimerization vanishes at the point of second-order quantum transition into the Neel ordered phase [(J(2)/J(1))(c1)approximate to 0.38]. We argue that the disappearance of dimer order is related to the vanishing of the singlet energy gap at the transition point. [S0163-1829(99 )04145-8].