Физика Низких Температур: Том 31, Выпуск 8-9 (Август 2005), c. 918-928    ( к оглавлению , назад )

Localized-magnon states in strongly frustrated quantum spin lattices

J. Richter

Institut für Theoretische Physik, Universität Magdeburg P.O. Box 4120, D-39016 Magdeburg, Germany
E-mail: Johannes.Richter@Physik.Uni-Magdeburg.DE

Received January 19, 2005

Аннотация

Recent developments concerning localized-magnon eigenstates in strongly frustrated spin lattices and their effect on the low-temperature physics of these systems in high magnetic fields are reviewed. After illustrating the construction and the properties of localized-magnon states we describe the plateau and the jump in the magnetization process caused by these states. Considering appropriate lattice deformations fitting to the localized magnons we discuss a spin-Peierls instability in high magnetic fields related to these states. Last but not least we consider the degeneracy of the localized-magnon eigenstates and the related thermodynamics in high magnetic fields. In particular, we discuss the low-temperature maximum in the isothermal entropy versus field curve and the resulting enhanced magnetocaloric effect, which allows efficient magnetic cooling from quite large temperatures down to very low ones.

PACS:
75.10.Jm - Quantized spin models
75.45.+j - Macroscopic quantum phenomena in magnetic systems
75.60.Ej - Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Ee - Antiferromagnetics