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arXiv 2602.21086cond-mat.str-elcond-mat.stat-mech
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用杂质探测反铁磁自旋系统

Probing frustrated spin systems with impurities

Institute of Theoretical Physics, Wrocław University of Science and Technology(弗罗茨瓦夫科技大学理论物理研究所)

Maksymilian Kliczkowski, Jakub Grabowski, Maciej M. Maśka

AI总结:

研究通过杂质相互作用探测反铁磁自旋系统,揭示了弱耦合和强耦合区域的不同相互作用行为,区分了无隙和有隙相。

摘要:

我们研究了两个嵌入在反铁磁自旋-1/2 J1-J2 Heisenberg 链中的局部自旋杂质之间的有效相互作用。将杂质自旋视为经典矩,局部耦合到基质中,我们结合二阶微扰理论和大规模密度矩阵重整化群(DMRG)计算,确定杂质-杂质相互作用作为分离、耦合强度和磁性反铁磁性函数的函数。在弱耦合区域,我们显示相互作用由基质的静态自旋磁化率支配,并在无隙相中表现出振荡的幂律衰减,这在SU(2)对称临界点处被普遍对数修正所修改。在有隙双极化相中,相互作用随距离指数衰减。对于中等和强杂质-基质耦合,我们观察到向边界主导区域的转变,其特征是与杂质之间链段长度相关的明显奇偶效应,表明了简单RKKY-like描述的崩溃。我们的结果确立了杂质-杂质相互作用作为反铁磁量子自旋液体的敏感探测器,并提供了一个受控框架,通过局部扰动来区分无隙和有隙相。

英文摘要:

We investigate the effective interaction between two localized spin impurities embedded in a frustrated spin-1/2 $J_1\!-\!J_2$ Heisenberg chain. Treating the impurity spins as classical moments coupled locally to the host, we combine second--order perturbation theory with large--scale density matrix renormalization group (DMRG) calculations to determine the impurity--impurity interaction as a function of separation, coupling strength, and magnetic frustration. In the weak--coupling regime, we show that the interaction is governed by the the static spin susceptibility of the host and exhibits oscillatory power--law decay in the gapless phase, modified by universal logarithmic corrections at the SU(2)--symmetric critical point. In the gapped dimerized phase, the interaction decays exponentially with distance. For intermediate and strong impurity--host coupling, we observe a crossover to a boundary--dominated regime characterized by pronounced parity effects associated with the length of the chain segment between impurities, signaling a breakdown of the simple RKKY--like description. Our results establish impurity--impurity interactions as a sensitive probe of frustrated quantum spin liquids and provide a controlled framework for distinguishing gapless and gapped phases through local perturbations.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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