论文标题
在海森伯格磁铁中，可触发的可触摸berezinskii-kosterlitz-无用的相关性
Field-tunable Berezinskii-Kosterlitz-Thouless correlations in a Heisenberg magnet
论文作者
论文摘要
我们报告了野外诱导的Berezinskii-Kosterlitz-thouless-thouless（bkt）相关性，该相关性在基于分子的散装材料的弱耦合旋转1/2海森贝格层中[Cu（pz）$ _ 2 $（2-hopy）$ _ 2 $ _ 2 $ _ 2 $ _ 2 $ _6 $ _6 $ _6 $ _ 2 $ _ 2 $ _ 2 $ _ 2 $ _ 2 $ _ 2 $ _ 2 $ _ 2 $ _ 2 $ _ 2 $ _ 2 $ _ 2 $ _ 2 $ _ 2 $ _2 $ _ 2 $ _ 2 $ _ 2 $ _ 2 $ _。由于$ j/k_ \ mathrm {b} = 6.8 $ k的中等内部交换耦合，实验室磁场的应用会引起自旋相关的大量$ xy $ anisotropy。至关重要的是，这提供了重要的BKT制度，因为微小的中间层交换$ j^\ prime / k_ \ mathrm {b} \大约1 $ MK仅在BKT转变近距离过渡时诱导3D相关性，其指数增长在自旋相关长度中。我们采用核磁共振和$μ^{+} $ SR测量来探测确定BKT过渡的临界温度以及远程顺序发作的临界温度的自旋相关性。此外，我们基于实验确定的模型参数执行随机系列量量蒙特卡洛模拟。平面内旋转刚度的有限尺寸缩放量表在理论和实验之间产生了极好的一致性，提供了明确的证据，表明[CU（PZ）$ _ 2 $ _ 2 $（2-HOPY）$ _ 2 $]的非单调磁相图（PF $ _6 $ _ 2 $）由现场the tuned $ xy $ xy $ xy $ ansisotriats确定。
We report the manifestation of field-induced Berezinskii-Kosterlitz-Thouless (BKT) correlations in the weakly coupled spin-1/2 Heisenberg layers of the molecular-based bulk material [Cu(pz)$_2$(2-HOpy)$_2$](PF$_6$)$_2$. Due to the moderate intralayer exchange coupling of $J/k_\mathrm{B} = 6.8$ K, the application of laboratory magnetic fields induces a substantial $XY$ anisotropy of the spin correlations. Crucially, this provides a significant BKT regime, as the tiny interlayer exchange $J^\prime / k_\mathrm{B} \approx 1$ mK only induces 3D correlations upon close approach to the BKT transition with its exponential growth in the spin-correlation length. We employ nuclear magnetic resonance and $μ^{+}$SR measurements to probe the spin correlations that determine the critical temperatures of the BKT transition as well as that of the onset of long-range order. Further, we perform stochastic series expansion quantum Monte Carlo simulations based on the experimentally determined model parameters. Finite-size scaling of the in-plane spin stiffness yields excellent agreement of critical temperatures between theory and experiment, providing clear evidence that the nonmonotonic magnetic phase diagram of [Cu(pz)$_2$(2-HOpy)$_2$](PF$_6$)$_2$ is determined by the field-tuned $XY$ anisotropy and the concomitant BKT physics.
