Eur. Phys. J. B 52, 23-36 (2006)
https://doi.org/10.1140/epjb/e2006-00273-y

Universal low-temperature behavior of frustrated quantum antiferromagnets in the vicinity of the saturation field

¹ 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 derzhko@icmp.lviv.ua

Received: 2 April 2006
Published online: 6 July 2006

Abstract

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.