The Kagome Antiferromagnet A SchwingerBoson MeanField Theory Study.pdfVIP

The Kagom´e Antiferromagnet: A Schwinger-Boson Mean-Field Theory Study Peng Li, Haibin Su Division of Materials Science, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 Shun-Qing Shen Department of Physics, The University of Hong Kong, Pokfulam, Hong Kong, China (Dated: February 2, 2008) The Heisenberg antiferromagnet on the Kagom´e lattice is studied in the framework of Schwinger- boson mean-field theory. Two solutions with different symmetries are presented. One solution gives 7 a conventional quantum state with q = 0 order for all spin values. Another gives a gapped spin 0 liquid state for spin S = 1/2 and a mixed state with both q = 0 and √3 × √3 orders for spin 0 S 1/2. We emphasize that the mixed state exhibits two sets of peaks in the static spin structure 2 factor. And for the case of spin S = 1/2, the gap value we obtained is consistent with the previous v numerical calculations by other means. We also discuss the thermodynamic quantities such as the o specific heat and magnetic susceptibility at low temperatures and show that our result is in a good N agreement with the Mermin-Wagner theorem. 3 PACS numbers: 75.10.Jm, 75.30.Ds, 75.40.Cx ] l e I. INTRODUCTION - r t s Two-dimensional (2D) geometrically frustrated Heisenberg antiferromagnets (AFMs) are potential candiadates in t. the search of sp