Schwinger boson spin liquid states on square lattice

TL;DR

This paper classifies and analyzes Z_2 spin liquid states on the square lattice using Schwinger boson mean-field theory, revealing potential phase transitions and connections to other spin liquid models.

Contribution

It introduces a classification of six Z_2 spin liquid states on the square lattice respecting all symmetries, using the projective symmetry group method.

Findings

Identifies six relevant spin liquid states for the J_1-J_2 model.

Discovers a spin liquid state with continuous transitions to magnetic orders.

Explores connections between bosonic and fermionic spin liquid descriptions.

Abstract

We study possible spin liquids on square lattice that respect all lattice symmetries and time-reversal symmetry within the framework of Schwinger boson (mean-field) theory. Such spin liquids have spin gap and emergent Z_2 gauge field excitations. We classify them by the projective symmetry group method, and find six spin liquid states that are potentially relevant to the J_1-J_2 Heisenberg model. The properties of these states are studied under mean-field approximation. Interestingly we find a spin liquid state that can go through continuous phase transitions to either the N\'eel magnetic order or magnetic orders of the wavevector at Brillouin zone edge center. We also discuss the connection between our results and the Abrikosov fermion spin liquids.