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arXiv 1107.2896cond-mat.str-el
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具有Dzyaloshinskiii-Moriya项的$S=1/2$链中价键序的破坏

Destruction of valence-bond order in a $S=1/2$ sawtooth chain with a Dzyaloshinskii-Moriya term

Zhihao Hao, Yuan Wan, Ioannis Rousochatzakis, Julia Wildeboer, A. Seidel, F. Mila, O. Tchernyshyov

摘要:

在具有强阻挫的量子反铁磁体中,自旋能隙的值很小,这使得它们对理想海森堡模型的名义上很小的偏差很敏感。其中一个扰动,各向异性Dzyaloshinskiii-Moriya相互作用,是一个重要的扰动的$S=1/2$戈薇反铁磁体,一个量子无序基态的当前候选人之一。我们研究了DM项在一个相关的一维系统中的影响,在其基态具有价键序的链。通过分析和数值计算相结合的方法,我们表明,一个相对较弱的DM耦合,$0.115J$,足以破坏价键顺序,关闭自旋间隙,并把系统变成一个Luttinger液体与代数自旋相关。一个类似的机制可能在戈薇反铁磁体中起作用。

英文摘要:

A small value of the spin gap in quantum antiferromagnets with strong frustration makes them susceptible to nominally small deviations from the ideal Heisenberg model. One of such perturbations, the anisotropic Dzyaloshinskii-Moriya interaction, is an important perturbation for the $S=1/2$ kagome antiferromagnet, one of the current candidates for a quantum-disordered ground state. We study the influence of the DM term in a related one-dimensional system, the sawtooth chain that has valence-bond order in its ground state. Through a combination of analytical and numerical methods, we show that a relatively weak DM coupling, $0.115J$, is sufficient to destroy the valence-bond order, close the spin gap, and turn the system into a Luttinger liquid with algebraic spin correlations. A similar mechanism may be at work in the kagome antiferromagnet.

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