Two-dimensional spin models with resonating valence bond ground states

Jennifer Chayes, Lincoln Chayes, Steven Allan Kivelson

Masanori Yamanaka, Shinsuke Honjo, Yasuhiro Hatsugai +1 more

Élliott H. Lieb

Indrani Bose

Two spin models in two dimensions are constructed for which the exact ground states can be written down in a certain parameter regime of the Hamiltonian. The ground state of the first model is a local resonating valence bond (RVB) state in which not all the spins participate in resonance. The ground state is highly degenerate and there is a gap in the excitation spectrum. The second model is shown to have a ground state which is a quantum spin liquid with all the spins taking part in resonance. The ground state obtained is non-degenerate and there is no gap in the excitation spectrum.

Sanyee Tang, H. Q. Lin

We have studied the relation between the resonating-valence-bond (RVB) state and the exact ground state for the two-dimensional antiferromagnetic (AF) Heisenberg model on a few small lattices. We describe a method to obtain the state of minimum energy within a family of RVB states. Based on the insight provided by the RVB states, and supported by our numerical results, we argue in favor of the existence of long-range order at T=0 for the two-dimensional AF Heisenberg model.

Ying Tang, Anders W. Sandvik