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Exact eigenstates of highly frustrated spin lattices probed in high fields

J. Schnack·H. -J. Schmidt·A. Honecker·J. Schulenburg·J. Richter
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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.

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J. Schnack, H. -J. Schmidt, A. Honecker, J. Schulenburg, J. Richter. 2006-07-20. Exact eigenstates of highly frustrated spin lattices probed in high fields. https://doi.org/10.1088/1742-6596%2F51%2F1%2F007

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