Exact eigenstates of highly frustrated spin lattices probed in high fields

Abstract

Strongly frustrated antiferromagnets such as the magnetic molecule {Mo72Fe30}, the kagome, or the pyrochlore lattice exhibit a variety of fascinating properties like low-lying singlets, magnetization plateaus as well as magnetization jumps. During recent years exact many-body eigenstates could be constructed for several of these spin systems. These states become ground states in high magnetic fields, and they also lead to exotic behavior. A key concept to an understanding of these properties is provided by independent localized magnons. The energy eigenvalue of these n-magnon states scales linearly with the number n of independent magnons and thus with the total magnetic quantum number M=Ns-n. In an applied field this results in a giant magnetization jump which constitutes a new macroscopic quantum effect. It will be demonstrated that this behavior is accompanied by a massive degeneracy, an extensive (T=0)-entropy, and thus a large magnetocaloric effect at the saturation field. The connection to flat band ferromagnetism will be outlined.

arXiv comment4 pages, submitted to the proceedings of the Yamada Conference LX on Research in High Magnetic Fields, August 16-19, 2006 Sendai, Japan

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Cited by in corpus (11)

• Highly Frustrated Magnetic Clusters: The kagome on a sphere
• Universal properties of highly frustrated quantum magnets in strong magnetic fields
• Dynamic and thermodynamic properties of the generalised diamond chain model for azurite
• Magneto-thermal properties of the Heisenberg-Ising orthogonal-dimer chain with triangular XXZ-clusters
• The sawtooth chain: From Heisenberg spins to Hubbard electrons
• Thermodynamics of antiferromagnetic alternating spin chains
• Magnetization process and ordering of the $S=1/2$ pyrochlore magnet in a field
• Spin-wave spectra of a kagome stripe
• $\mathbf{\Delta }$S${}^z$=2 quantum magnetization discontinuities proportional in number to the spin s in C${}_{60}$: Origin and the role of symmetry
• Magnetization curve of the kagome-strip-lattice antiferromagnet
• Origin of the classical magnetization discontinuities of the dodecahedron