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

Kazuo Ueda, Hiroshi Kontani, Manfred Sigrist +1

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 resona…