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Plaquette Resonating-Valence-Bond Ground State of CaV$_4$O$_9$

Kazuo Ueda·Hiroshi Kontani·Manfred Sigrist·Patrick A. Lee
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Abstract

A theoretical model is presented to explain the spin gap observed for CaV$_4$O$_9$. The underlying lattice of the 1/5-depleted square lattice favors a formation of plaquette resonating valence bond state. Inclusion of the frustrating second neighbor interaction enhances this tendency, leading to a quantum disordered state of a two dimensional spin-1/2 Heisenberg model with a sufficiently big spin gap compatible with experiments.

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Kazuo Ueda, Hiroshi Kontani, Manfred Sigrist, Patrick A. Lee. 1995-11-08. Plaquette Resonating-Valence-Bond Ground State of CaV$_4$O$_9$. https://doi.org/10.1103/physrevlett.76.1932

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