The Heisenberg model on a stackedtriangular lattice: spin Green function approach
Abstract
Using a spin Green function approach, we have studied the magnetic properties of a stackedtriangular Heisenberg model, in which the triangular lattice is in the xy plane and the triangular nets are stacked in parallel along the z axis. We consider both the quasitwo and the quasionedimensional cases and suppose the interaction between the nearestneighbor spins to be antiferromagnetic or ferromagnetic. By computing the magnetization and the transition temperature of the system, we find that the geometrical frustration introduced by the antiferromagnetic exchange in a triangular lattice brings about an additional spin fluctuation, which results in a decrease of the staggered magnetization and a lowering of the transition temperature compared to the system without geometrical frustration. In the quasitwodimensional case, the exchange strength J in the xy plane is much larger than J along the z direction (J J), and in the quasionedimensional case (J J) the transition temperatures can be expressed in approximation forms as T_{N} = S(S + 1)J/[aln (J/J) + b and T_{N} = cS(S + 1)(JJ)^{1/2}, respectively. (
 Publication:

Physica Status Solidi B Basic Research
 Pub Date:
 November 2003
 DOI:
 10.1002/pssb.200301879
 Bibcode:
 2003PSSBR.240..230D
 Keywords:

 75.10.Jm;75.30.Ds;75.30.Kz;75.50.Ee