Valence Bond Solid Phases on Deformed Kagome Lattices: Application to Rb2Cu3SnF12

Understand

Motivated by a recent experiment on Rb2Cu3SnF12, where spin-1/2 Cu2+ moments reside on the layers of Kagome-like lattices, we investigate quantum ground states of the antiferromagnetic Heisenberg model on a series of deformed Kagome lattices.

• The deformation is characterized by a weaker exchange coupling (alpha*J) on certain lattice links appropriate for Rb2Cu3SnF12 with alpha=1 corresponding to the ideal Kagome lattice.
• In particular, we study possible valence bond solid phases using the perturbation theory around isolated dimer limits, dimer series expansion, and self-consistent bond operator mean field theory.
• It is shown that the valence bond solid phase with a 36-site unit cell of the ideal Kagome lattice is quite sensitive to a small lattice distortion as the kind discovered in Rb2Cu3SnF12.