Z(2) gauge theory for valence bond solids on the kagome lattice

Article

关键词: HEISENBERG-ANTIFERROMAGNET;    SPIN LIQUIDS;    STATE;    EXCITATIONS;    SUPERCONDUCTIVITY;    SYSTEMS;   

DOI  :  10.1103/PhysRevB.92.205131

来源: SCIE

【 摘 要 】

We present an effective Z(2) gauge theory that captures various competing phases in spin-1/2 kagome lattice antiferromagnets: the topological Z(2) spin liquid (SL) phase, and the 12-site and 36-site valence bond solid (VBS) phases. Our effective theory is a generalization of the recent Z(2) gauge theory proposed for SL phases by Wan and Tchernyshyov. In particular, we investigate possible VBS phases that arise from vison condensations in the SL. In addition to the 12-site and 36-site VBS phases, there exists 6-site VBS that is closely related to the symmetry-breaking valence bond modulation patterns observed in the recent density matrix renormalization group simulations. We find that our results have remarkable consistency with a previous study using a different Z(2) gauge theory. Motivated by the lattice geometry in the recently reported vanadium oxyfluoride kagome antiferromagnet, our gauge theory is extended to incorporate lowered symmetry by inequivalent up and down triangles. We investigate effects of this anisotropy on the 12-site, 36-site, and 6-site VBS phases. The 12-site VBS is stable to anisotropy while the 36-site VBS undergoes severe dimer melting. Interestingly, any analog of the 6-site VBS is not found in this approach. We discuss the implications of these findings and also compare the results with a different type of Z(2) gauge theory used in previous studies.

【 授权许可】

Free