Localized-magnon states in strongly frustrated quantum spin lattices

TL;DR

This paper reviews the role of localized-magnon eigenstates in frustrated quantum spin lattices, highlighting their impact on magnetization, lattice instabilities, degeneracy, and potential for magnetic cooling at low temperatures.

Contribution

It provides a comprehensive analysis of localized-magnon states, their construction, effects on magnetization jumps, spin-Peierls instability, and thermodynamic properties in high magnetic fields.

Findings

Localized-magnon states cause magnetization plateaus and jumps.

Degeneracy of these states leads to a low-temperature entropy maximum.

Enhanced magnetocaloric effect enables efficient magnetic cooling.

Abstract

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.