The Heisenberg antiferromagnet on an anisotropic triangular lattice: linear spin-wave theory

Merino, J, McKenzie, RH, Marston, JB and Chung, CH (1999) The Heisenberg antiferromagnet on an anisotropic triangular lattice: linear spin-wave theory. Journal of Physics-condensed Matter, 11 14: 2965-2975. doi:10.1088/0953-8984/11/14/012


Author Merino, J
McKenzie, RH
Marston, JB
Chung, CH
Title The Heisenberg antiferromagnet on an anisotropic triangular lattice: linear spin-wave theory
Journal name Journal of Physics-condensed Matter   Check publisher's open access policy
ISSN 0953-8984
Publication date 1999-01-01
Sub-type Article (original research)
DOI 10.1088/0953-8984/11/14/012
Volume 11
Issue 14
Start page 2965
End page 2975
Total pages 11
Language eng
Abstract We consider the effect of quantum spin fluctuations on the ground-state properties of the Heisenberg antiferromagnet on an anisotropic triangular lattice using linear spin-wave (LSW) theory. This model should describe the magnetic properties of the insulating phase of the kappa-(BEDT-TTF)(2)X family of superconducting molecular crystals. The ground-state energy, the staggered magnetization, magnon excitation spectra, and spin-wave velocities are computed as functions of the ratio of the antiferromagnetic exchange between the second and first neighbours, J(2)/J(1). We find that near J(2)/J(1) = 0.5, i.e., in the region where the classical spin configuration changes from a Neel-ordered phase to a spiral phase, the staggered magnetization vanishes, suggesting the possibility of a quantum disordered state. in this region, the quantum correction to the magnetization is large but finite. This is in contrast to the case for the frustrated Heisenberg model on a square lattice, for which the quantum correction diverges logarithmically at the transition from the Neel to the collinear phase. For large J(2)/J(1), the model becomes a set of chains with frustrated interchain coupling. For J(2) > 4J(1), the quantum correction to the magnetization, within LSW theory, becomes comparable to the classical magnetization, suggesting the possibility of a quantum disordered state. We show that, in this regime, the quantum fluctuations are much larger than for a set of weakly coupled chains with non-frustrated interchain coupling.
Keyword Physics, Condensed Matter
Frustrated Quantum Antiferromagnets
Temperature Properties
Organic Conductors
Phase-diagram
Superconductivity
Order
Insulator
Disorder
Chains
Model
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collections: Centre for Organic Photonics and Electronics
School of Physical Sciences Publications
 
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Created: Mon, 13 Aug 2007, 21:01:59 EST