Department of Theoretical Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Navy Nagar, Mumbai-400005, India.
Phys Rev Lett. 2010 Sep 10;105(11):117201. doi: 10.1103/PhysRevLett.105.117201. Epub 2010 Sep 7.
We study the effect of coupling magnetic impurities to the honeycomb lattice spin-1/2 Kitaev model in its spin-liquid phase. We show that a spin-S impurity coupled to the Kitaev model is associated with an unusual Kondo effect with an intermediate coupling unstable fixed point Kc∼J/S separating topologically distinct sectors of the Kitaev model. We also show that the massless spinons in the spin-liquid mediate an interaction of the form Siα2Sjβ2/Rij3 between distant impurities unlike the usual dipolar RKKY interaction SiαSjα/Rij3 noted in various 2D impurity problems with a pseudogapped density of states of the spin bath. Furthermore, this long-range interaction is possible only if the impurities (a) couple to more than one neighboring spin on the host lattice and (b) the impurity spin S≠1/2.
我们研究了耦合磁杂质对蜂窝晶格自旋-1/2 Kitaev 模型在其自旋液体相中的影响。我们表明，与 Kitaev 模型耦合的自旋-S 杂质与不寻常的 Kondo 效应相关联，其中中间耦合不稳定固定点 Kc∼J/S 分隔了 Kitaev 模型的拓扑上不同的区域。我们还表明，自旋液体中的无质量自旋子介导了一种形式为 Siα2Sjβ2/Rij3 的相互作用，这种相互作用在具有自旋浴态的各种二维杂质问题中通常的偶极 RKKY 相互作用 SiαSjα/Rij3 不同，不同于具有伪间隙态的各种 2D 杂质问题中的通常的偶极 RKKY 相互作用 SiαSjα/Rij3。此外，只有当杂质（a）与宿主晶格上的一个以上相邻自旋耦合，并且（b）杂质自旋 S≠1/2 时，才可能存在这种长程相互作用。
