Dzyaloshinskii-Moriya interactions in valence bond systems

Abstract

We investigate the effect of Dzyaloshinskii-Moriya interactions on the low temperature magnetic susceptibility for a system whose low energy physics is dominated by short-range valence bonds (singlets). Our general perturbative approach is applied to specific models expected to be in this class, including the Shastry-Sutherland model of the spin-dimer compound SrCu_2(BO_3)_2 and the antiferromagnetic Heisenberg model of the recently discovered S=1/2 kagome compound ZnCu_3(OH)_6Cl_2. The central result is that a short-ranged valence bond phase, when perturbed with Dzyaloshinskii-Moriya interactions, will remain time-reversal symmetric in the absence of a magnetic field but the susceptibility will be nonzero in the T\to 0 limit. Applied to ZnCu_3(OH)_6Cl_2, this model provides an avenue for reconciling experimental results, such as the lack of magnetic order and lack of any sign of a spin gap, with known theoretical facts about the kagome Heisenberg antiferromagnet.

15 pages, 7 figures; An error in version 2 has been corrected which changes our conclusions (Eq. 8 of version 2 does not apply for systems that do not conserve spin)

References in corpus (6)

• Spin Dynamics of the Spin-1/2 Kagome Lattice Antiferromagnet ZnCu_3(OH)_6Cl_2
• Projected wavefunction study of Spin-1/2 Heisenberg model on the Kagome lattice
• Quantum magnetism in the paratacamite family: towards an ideal kagome lattice
• Properties of an algebraic spin liquid on the kagome lattice
• ^{63}Cu, ^{35}Cl, and ^{1}H NMR in the S=1/2 Kagomé Lattice ZnCu_{3}(OH)_{6}Cl_{2}
• Magnetic Susceptibility of the Kagome Antiferromagnet ZnCu3(OH)6Cl2

Cited by in corpus (1)

• Dzyaloshinskii-Moriya anisotropy and non-magnetic impurities in the $s=1/2$ kagome system ZnCu_3(OH)_6Cl_2