Abstract
We investigate the zero-temperature phase diagram of the nearest-neighbor kagome antiferromagnet in the presence of Dzyaloshinksii-Moriya interaction. We develop a theory for the transition between Z2 spin liquids with bosonic spinons and a phase with antiferromagnetic long-range order. Connections to recent numerical studies and experiments are discussed.
Highlights
The nearest neighbor spin S =1 2 antiferromagnet on the kagome lattice has been the focus of extensive theoretical and experimental study because it is a prime candidate for realizing a ground state without antiferromagnetic order.On the experimental side, much attention has focused on the S = 1/2 compound herbertsmithiteZnCu3(OH)6Cl2
The purpose of this paper is to propose a theory for the quantum critical point discovered by Cepas et al
The main result of this paper will be a theory of the quantum phase transition from the Schwinger boson Z2 spin liquid to the magnetically ordered state as induced by the DM interactions
Summary
1 2 antiferromagnet on the kagome lattice has been the focus of extensive theoretical and experimental study because it is a prime candidate for realizing a ground state without antiferromagnetic order. In a recent exact diagonalization study, Cepas et al. reach a different conclusion: they claim that there is a non-zero critical DM coupling Dc beyond which magnetic order is induced They estimate Dc/J ≈ 0.1, quite close to the value measured for ZnCu3(OH)6Cl2 which has D/J ≈ 0.08. The main result of this paper will be a theory of the quantum phase transition from the Schwinger boson Z2 spin liquid to the magnetically ordered state as induced by the DM interactions. This will be carried using the Sp(N ) Schwinger boson formulation, for which the meanfield theory becomes exact in the large N limit. We note the recent experimental observations of Helton et al., who present evidence for quantum criticality in ZnCu3(OH)6Cl2
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