Hund metals have attracted attention in recent years due to their unconventional superconductivity, which supposedly originates from non-Fermi-liquid (NFL) properties of the normal state. When studying Hund metals using dynamical mean-field theory, one arrives at a self-consistent “Hund impurity problem” involving a multiorbital quantum impurity with nonzero Hund coupling interacting with a metallic bath. If its spin and orbital degrees of freedom are screened at different energy scales, $T_{\mathrm{sp}}<T_{\text{orb}}$, the intermediate energy window is governed by a novel NFL fixed point, whose nature had not yet been clarified. We resolve this problem by providing an analytical solution of a paradigmatic example of a Hund impurity problem, involving two spin and three orbital degrees of freedom. To this end, we combine a state-of-the-art implementation of the numerical renormalization group, capable of exploiting non-Abelian symmetries, with a generalization of Affleck and Ludwig’s conformal field theory (CFT) approach for multichannel Kondo models. We characterize the NFL fixed point of Hund metals in detail for a Kondo model with an impurity forming an $\mathrm{SU}(2)\times \mathrm{SU}(3)$ spin-orbital multiplet, tuned such that the NFL energy window is very wide. The impurity’s spin and orbital susceptibilities then exhibit striking power-law behavior, which we explain using CFT arguments. We find excellent agreement between CFT predictions and numerical renormalization group results. Our main physical conclusion is that the regime of spin-orbital separation, where orbital degrees of freedom have been screened but spin degrees of freedom have not, features anomalously strong local spin fluctuations: the impurity susceptibility increases as ${\chi }_{\mathrm{sp}}^{\text{imp}}\sim {\omega }^{-\gamma }$, with $\gamma >1$.

中文翻译：

---

发现高金属中的非费米液体行为：anSU（2）×SU（3）自旋轨道近藤模型的共形场理论分析

近年来，由于金属具有非常规的超导性，因此引起了人们的关注。超导性据推测源于正常状态的非费米液体（NFL）特性。当使用动力学平均场理论研究洪德金属时，会得出一个自洽的“洪德杂质问题”，其中涉及多轨道量子杂质，非零洪德耦合与金属浴相互作用。如果在不同的能级上筛选其自旋和轨道自由度，${Ť}_{\mathrm{SP}}<{Ť}_{\text{宝珠}}$，中间能量窗口由一个新颖的NFL定点控制，该定点的性质尚未阐明。我们通过提供涉及两个自旋和三个轨道自由度的Hund杂质问题的范例的解析解决方案来解决此问题。为此，我们将能够利用非阿贝尔对称性的数值重整化组的最新实现方式与对多通道近藤模型的Affleck和路德维希共形场论（CFT）方法的一般化相结合。我们详细描述了近藤金属的NFL定点，其杂质形成了近藤模型。$苏（2）\times 苏（3）$自旋轨道多重峰，经过调整使得NFL能量窗口非常宽。然后，杂质的自旋和轨道磁化率表现出惊人的幂律行为，我们将使用CFT论点对其进行解释。我们发现CFT预测与数值重归一化组结果之间具有极好的一致性。我们的主要物理结论是，自旋轨道分离机制（其中已筛选了轨道自由度，但没有筛选自旋自由度）具有异常强烈的局部自旋波动：杂质敏感性随着${\chi }_{\mathrm{SP}}^{\text{小鬼}}〜{\omega }^{-\gamma }$，带有 $\gamma >\mathrm{1个}$。