发表机构
The University of Hong Kong; Univ Toulouse, CNRS, Laboratoire de Physique Théorique; Institute of Physics, Chinese Academy of Sciences; University of Chinese Academy of Sciences（香港大学; 图卢兹大学，法国国家科学研究中心，理论物理实验室; 中国科学院物理研究所; 中国科学院大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过DMRG和NQS模拟及热张量网络计算，揭示了kagome 3J模型的中间量子自旋液体相及其比热特征，连接了微观模型与实验观测。
AI 中文摘要
我们研究了具有三种不等价耦合的kagome反铁磁海森堡模型（称为$3J$模型）的基态和有限温度性质，该模型是为候选Dirac量子自旋液体（QSL）材料YCu$_3$(OH)$_6$Br$_2$[Br$_{1-x}$(OH)$_x$]设计的（参见，例如，Zeng等人，2024）。通过采用大规模密度矩阵重正化群（DMRG）方法并辅以神经量子态（NQS）模拟，我们在两个磁有序相之间识别出一个中间QSL相。我们还发现，该QSL在各向同性极限下与kagome自旋液体基态是分离的。为了与实验进行直接比较，我们利用先进的指数（XTRG）和切空间（tanTRG）热张量网络方法计算了该模型的比热。在磁有序相中，比热除以温度在温度为耦合强度$J_{hex}$的一个分数处呈现出一个肩状结构，而在QSL相中该肩状结构消失。这些普适行为与实验观测到的$3J$材料中有序和QSL候选样品的比热一致。因此，我们的工作将微观模型与实验可测量的特征联系起来，体现了一种理解阻挫量子磁体中QSL现象的综合方法（参见Meng等人，2026），其中$3J$材料作为代表性案例，并为未来研究提供了基础。
英文摘要
We investigate the ground-state and finite-temperature properties of the kagome antiferromagnetic Heisenberg model with three inequivalent couplings, dubbed the $3J$ model, which is designed for the candidate Dirac quantum spin liquid (QSL) material YCu$_3$(OH)$_6$Br$_2$[Br$_{1-x}$(OH)$_x$] (see, e.g., Zeng et al., 2024). Employing large-scale density-matrix renormalization group (DMRG) supplemented by neural quantum states (NQS) simulations, we identify an intermediate QSL phase between two magnetically ordered phases. We also find that this QSL is separated from the kagome spin liquid ground state at the isotropic limit. To establish a direct comparison with experiments, we compute the specific heat of the model by means of advanced exponential (XTRG) and tangent-space (tanTRG) thermal tensor-network methods. In the magnetically ordered phase, the specific heat over temperature exhibits a shoulder at a temperature that is a fraction of the coupling strength $J_{h}$, which disappears in the QSL phase. These universal behaviors are consistent with the experimentally observed specific heat in $3J$ materials for both ordered and QSL candidate samples. Our work thus connects microscopic models with experimentally measurable signatures, exemplifying an integrated approach to understanding QSL phenomena in frustrated quantum magnets~ (see Meng et al., 2026), with $3J$ materials serving as a representative case and providing a foundation for future studies.
Comments9+7 pages, 5+7 figures
