Universal low-temperature behavior of frustrated quantum antiferromagnets in the vicinity of the saturation field
Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine, 1 Svientsitskii Street, L'viv, 79011, Ukraine
2 Institut für Theoretische Physik, Universität Magdeburg, P.O. Box 4120, 39016 Magdeburg, Germany
Corresponding author: a email@example.com
Published online: 6 July 2006
We study the low-temperature thermodynamic properties of a number of frustrated quantum antiferromagnets which support localized magnon states in the vicinity of the saturation field. For this purpose we use (1) a mapping of the low-energy degrees of freedom of spin systems onto the hard-core object lattice gases and (2) an exact diagonalization of finite spin systems of up to N=30 sites. The considered spin systems exhibit universal behavior which is determined by a specific hard-core object lattice gas representing the independent localized magnon states. We test the lattice gas description by comparing its predictions with the numerical results for low-lying energy states of finite spin systems. For all frustrated spin systems considered we find a strong variation of the low-temperature specific heat passing the saturation field and a maximum in the isothermal entropy at saturation field resulting in an enhanced magnetocaloric effect.
PACS: 75.10.Jm – Quantized spin models / 75.45.+j – Macroscopic quantum phenomena in magnetic systems / 75.30.Sg – Magnetocaloric effect, magnetic cooling
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2006