Response and phase transition of a Kitaev spin liquid in a local magnetic field
Response and phase transition of a Kitaev spin liquid in a local magnetic field
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局域磁场中基塔耶夫自旋液体的响应和相变
DOI：
10.1103/physrevb.98.104410
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发表时间：
2018
影响因子：
3.7
通讯作者：
Wang Qiang-Hua
中科院分区：
文献类型：
--
作者：
Liang Shuang;He Bo-Sen;Dong Zhao-Yang;Chen Wei;Li Jian-Xin;Wang Qiang-Hua
研究了Kitaev自旋液体(KSL)对垂直于Kitaev蜂窝晶格的局域磁场的响应。局域磁场诱导自旋液体中磁通对的动态激发，系统可用一般的粒子-空穴非对称相互作用共振能级模型来描述。即使对弱磁场的微扰响应，磁通对的动态激发也局部地闭合了无间隙KSL的自旋关联函数谱中的磁通间隙。在微扰区之外，p-h不对称性与磁场竞争，并导致丰富的相图。此外，磁场打破了基态铁磁和反铁磁Kitaev耦合的规范等价性，导致了两种情况下的行为截然不同。反铁磁体在磁化过程中经历一次向偏振态的相变，而铁磁性体则不经历。这项研究可以推广到均匀磁场中的Kitaev模型，并可能有助于理解最近关于KSL候选者的实验问题。
We study the response of the Kitaev spin liquid (KSL) to a local magnetic field perpendicular to the Kitaev honeycomb lattice. The local magnetic field induces a dynamical excitation of a flux pair in the spin liquid and the system can be described by a generally particle-hole asymmetric interacting resonant level model. The dynamical excitation of the flux pair closes the flux gap in the spectrum of the spin correlation function locally for the gapless KSL even from the perturbative response to a weak magnetic field. Beyond the perturbative regime, the p-h asymmetry competes with the magnetic field and results in a rich phase diagram. Moreover, the magnetic field breaks the gauge equivalence of the ferromagnetic and anti-ferromagnetic Kitaev couplings of the ground state and leads to very different behaviors for the two cases. The anti-ferromagnetic case experiences a first order phase transition to the polarized state during magnetization whereas the ferromagnetic case does not. This study can be generalized to the Kitaev model in a uniform magnetic field and may help understand issues in recent experiments on KSL candidates.