The Plaquette Ground State of the Shastry-Sutherland Model

TL;DR

This paper provides numerical evidence that the ground state of the Shastry-Sutherland model at a specific coupling ratio is a plaquette state, using an advanced DMRG method suitable for strongly frustrated 2D spin systems.

Contribution

It introduces a two-step DMRG approach based on two-leg ladder expansion to study the ground state of the Shastry-Sutherland model in the strong frustration regime.

Findings

Numerical evidence of a plaquette ground state at J2=1.3J1.

DMRG method is effective in the strong frustration regime.

Complementary to quantum Monte Carlo in frustrated systems.

Abstract

I use the two-step density-matrix renormalization group method based on two-leg ladder expansion to show numerical evidence of a plaquette ground state for $J_2=1.3J_1$ in the Shastry-Sutherland model. I argue that the DMRG method is very efficient in the strong frustration regime of two-dimensional spin models where a spin-Peierls ground state is expected to occur. It is thus complementary to quantum Monte Carlo algorithms, which are known to work well in the small frustration regime but which are plagued by the sign problem in the strong frustration regime.