Kagome antiferromagnet : a Schwinger-boson mean-field theory study

Abstract

The Heisenberg antiferromagnet on the kagome lattice is studied in the framework of Schwinger-boson

mean-field theory. Two solutions with different symmetries are presented. One solution gives a conventional

quantum state with q=0 order for all spin values. Another gives a gapped spin liquid state for spin S= 1/2 and a

mixed state with both q=0 and √3 × √3 orders for spin S > 1/2 . We emphasize that the mixed state exhibits two

sets of peaks in the static spin structure factor. For the case of spin S= 1/2 , the gap value we obtained is

consistent with the previous numerical calculations by other means. We also discuss the thermodynamic

quantities such as the specific heat and magnetic susceptibility at low temperatures and show that our result is

in a good agreement with the Mermin-Wagner theorem.