Some peculiar properties of the complex magnetic systems

• Published in: Physica Status Solidi (b) 2004-02, Vol.241 (2), p.401-410
• Main Authors: Kapor, D., Pavkov, M., Manojlović, M., Pantić, M., Škrinjar, M., Stojanović, S.
• Format: Article
• Language: English
• Subjects: 75.10.Jm; 75.30.Ds; 75.50.Dd; 75.50.Gg; 75.70.Cn; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; General theory and models of magnetic ordering; Magnetic properties and materials; Physics; Quantized spin models
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.200301929

We treat two Heisenberg systems with complex magnetic structures: system with three sublattices and superlattice with three‐plane motive, with both ferromagnetic and antiferromagnetic coupling. Within Bloch's spin‐wave approximation they can be represented by a simple bosonic Hamiltonian with anomalous coupling. We show that the energies of the system can be derived by both Green function approach or so called “u–v” transformation. The basic result is that for a particular relation between sublattice spins i.e. S2 = S1 + S3 the system possess two acoustic (gapless) energy branches with linear dispersion law for small wave‐vectors. This leads to peculiar properties. In the Mean Field formalism, we show that the system in this case manifests so called weak ferromagnetism, and for certain system parameters, the three plane superlattice can posses one or even two compensation temperatures. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)