Realization of a large J(2) quasi-2D spin-half Heisenberg system: Li(2)VOSiO(4).
Exchange couplings are calculated for Li(2)VOSiO(4) using the local-density approximation (LDA). While the sum of in-plane couplings J(1)+J(2) = 9.5+/-1.5 K and the interplane coupling J( perpendicular) approximately 0.2- 0.3 K agree with recent experimental data, the ratio J(2)/J(1) approximately 12 exceeds the reported value by an order of magnitude. Using geometrical considerations, high temperature expansions and perturbative mean field theory, we show that the LDA-derived exchange constants lead to a remarkably accurate description of the properties of these materials including specific heat, susceptibility, Néel temperature, and NMR spectra.
Rosner
H
H
Department of Physics, University of California, Davis, CA 95616, USA.
Singh
R R P
RR
Zheng
W H
WH
Oitmaa
J
J
Drechsler
S-L
SL
Pickett
W E
WE