论文标题
在动态平均磁场理论中，在量子临界的量子临界时出现的软间隙安德森模型
Emergent soft-gap Anderson models at quantum criticality in a lattice Hamiltonian within dynamical mean field theory
论文作者
论文摘要
通过软间隙安德森杂质模型对巡回费米昂系统中的局部量子临界性进行了广泛的研究，其中局部相关的杂质与具有单数，$ |ω|^r $的广泛传导带杂交。但是，载有量子临界点（QCP）的晶格模型似乎在QCP处出现了这样的频谱。在这项工作中，我们报告了在动态平均磁场理论中，在三轨晶格模型中，状态密度的奇异形式的出现正是在量子临界点处，将无间隙，费米液体，金属相分开与间隙，mott的绝缘相。使用相应的Matsubara自能量定义的温度依赖性指数$α$，发现从FL制度中的$+1 $+$ -1 $不等。有趣的是，我们发现$α$变得独立于温度，因此恰好在QCP处于同性温度。表现出等级指数导致QCP处出现的软间隙频谱，其中$ |ω|^r $，其中$ r = |α_ {\ rm ISO} | $。我们讨论了我们发现对非Fermi液体行为的含义，在相图的量子临界区域中。
Local quantum criticality in itinerant fermion systems has been extensively investigated through the soft-gap Anderson impurity model, wherein a localized, correlated impurity, hybridizes with a broad conduction band with a singular, $|ω|^r$, density of states. However, lattice models hosting quantum critical points (QCPs), do not appear to have such a spectrum emerging at the QCP. In this work, we report the emergence of such a singular form of the density of states in a three-orbital lattice model, within dynamical mean field theory, precisely at a quantum critical point, separating a gapless, Fermi liquid, metallic phase from a gapped, Mott insulating phase. A temperature-dependent exponent, $α$, defined using the corresponding Matsubara self-energy, is found to vary from $+1$ deep in the FL regime, to $-1$ in the Mott insulator regime. Interestingly, we find that $α$ becomes temperature independent, and hence isosbestic, precisely at the QCP. The isosbestic exponent is shown to lead to an emergent soft-gap spectrum, $|ω|^r$ at the QCP, where $r = |α_{\rm iso}|$. We discuss the implications of our findings for non-Fermi liquid behaviour in the quantum critical region of the phase diagram.
