Simulating a two-dimensional frustrated spin system with fermionic resonating-valence-bond states

Abstract

The frustrated Heisenberg $J_1-J_2$ model on a square lattice is numerically investigated by variational Monte Carlo simulations. We propose a antiferromagnetic fermion resonating-valence-bond (AF-fRVB) state that has ability to examine the entire phase diagram in the $J_1-J_2$ model. Two phase transition points, the second order around $J_2/J_1=0.45$ and the first order around $J_2/J_1=0.6$, can be extracted more clearly than the conventional bosonic RVB state. At the maximally frustrated point ($J_2/J_1=0.5$), the AF-fRVB state shows the variational ground-state energy in the thermodynamic limit very close to the one estimated by the projected entangled pair state at the largest bond dimension available. On the other hand, in the frustrated regime $0.4\lesssim J_2/J_1\le 0.5$, AF-fRVB states with $s_{+-}$ (using the terminology in the field of iron-based superconductors) and $d_{xy}$ pairing symmetries are degenerate in the thermodynamic limit, implying the existence of gapless Dirac excitations in the spinon spectrum.

5 pages, 4 figures

References in corpus (5)

• Projected wavefunction study of Spin-1/2 Heisenberg model on the Kagome lattice
• Plaquette valence bond solid in the frustrated Heisenberg quantum antiferromagnet on the square lattice
• Ground-state phases of the spin-1/2 J_1-J_2 Heisenberg antiferromagnet on the square lattice: A high-order coupled cluster treatment
• Symplectic N and time reversal in frustrated magnetism
• Variational ground states of 2D antiferromagnets in the valence bond basis

Cited by in corpus (1)

• The spin-1/2 square-lattice J_1-J_2 model: The spin-gap issue