The dynamics of charge carriers close to the Mott transition is explored theoretically and experimentally in the quasi two-dimensional organic charge-transfer salt $κ$-(BEDT-TTF)$_2$Cu[N(CN)$_2$]Br$_x$Cl$_{1-x}$, with varying Br content. The frequency dependence of the conductivity deviates significantly from simple Drude model behavior: there is a strong redistribution of spectral weight as the Mott transition is approached and with temperature. The effective mass of the quasiparticles increases considerably when coming close to the insulating phase. A dynamical mean-field-theory treatment of the relevant Hubbard model gives a good quantitative description of the experimental data.
We clarify the origin of the strikingly different spectroscopic properties of the chemically similar compounds NaOsO$_3$ and LiOsO$_3$. Our first-principle many-body analysis demonstrates that the highly sensitive physics of these two materials is controlled by their proximity to an adjacent Hund's-Mott insulating phase. In mildly correlated $5d$ oxides, this physics is triggered by the {\sl cooperative} action of intraorbital repulsion and Hund's exchange in half-filled $t_{2g}$ outer-shells. Small material-specific details hence result in an extremely sharp change of the electronic mobility,…
Landau suggested that the low-temperature properties of metals can be understood in terms of long-lived quasiparticles with all complex interactions included in Fermi-liquid parameters, such as the effective mass $m^{\star}$. Despite its wide applicability, electronic transport in bad or strange metals and unconventional superconductors is controversially discussed towards a possible collapse of the quasiparticle concept. Here we explore the electrodynamic response of correlated metals at half filling for varying correlation strength upon approaching a Mott insulator. We reveal persistent Ferm…
A weird electronic state accompanied with an anomalous superconducting precursor and/or exotic orders, called the pseudogap state, arises prior to a superconducting condensate in underdoped cuprates that are situated near Mott transition. Another way to make the system approach the Mott transition is the variation of bandwidth or correlation strength, which gives a new dimension to exploring this exotic state. Here we report nuclear magnetic resonance (NMR) studies on layered organic superconductors with half-filled bands whose widths are pressure-tuned near the Mott transition. The system sit…
How a Mott insulator develops into a weakly coupled metal upon doping is a central question to understanding various emergent correlated phenomena. To analyze this evolution and its connection to the high-$T_c$ cuprates, we study the single-particle spectrum for the doped Hubbard model using cluster perturbation theory on superclusters. Starting from extremely low doping, we identify a heavily renormalized quasiparticle dispersion that immediately develops across the Fermi level, and a weakening polaronic side band at higher binding energy. The quasiparticle spectral weight roughly grows at tw…
Slater to Mott crossover in the metal to insulator transition of Nd2Ir2O7
我们提出了一个角度分辨的光电子能谱研究的三维烧绿石铱酸盐Nd 2 Ir 2 O 7通过其磁性金属-绝缘体转变的电子结构。我们的数据表明，金属Nd 2 Ir 2 O 7有一个二次带，接触费米能级在伽马点，类似于Pr 2 Ir 2 O 7。因此，费米节点状态是烧绿石铱酸盐的金属相的共同特征。当冷却到转变温度以下时，该化合物表现出带隙开口，具有像带隙绝缘体的准粒子峰的能量偏移。然而，随着温度的进一步降低，准粒子峰被强烈抑制，并最终在最低温度下消失，留下缺乏长寿命电子的非色散平坦带。因此，我们确定了一个显着的交叉从斯莱特到莫特绝缘体随着温度的降低。这些观察结果解释了这种材料中令人困惑的外尔点的缺失，尽管它接近于零温度金属-绝缘体转变。
Numerically exact simulation of photo-doped Mott insulators
University of Hamburg（汉堡大学）；University of Michigan（密歇根大学）；Graz University of Technology（格拉茨工业大学）；Tel Aviv University（特拉维夫大学）；The Hamburg Centre for Ultrafast Imaging（汉堡超快成像中心）
本文提出利用数值精确的稳态Quantum Monte Carlo技术，结合时间局域分布函数ansatz，计算Mott绝缘体中长寿命光掺杂态的性质，发现Mott能隙对大光掺杂保持稳健且准粒子性质被强重整化。
Nonlinear phononics holds the promise for controlling properties of quantum materials on the ultrashort timescale. Using nonequilibrium dynamical mean-field theory, we solve a model for the description of organic solids, where correlated electrons couple nonlinearly to a quantum phonon mode. Unlike previous works, we exactly diagonalize the local phonon mode within the noncrossing approximation to include the full phononic fluctuations. By exciting the local phonon in a broad range of frequencies near resonance with an ultrashort pulse, we show it is possible to induce a Mott insulator-to-meta…
We propose an energy-scale correspondence between the Mott physics and the Kondo lattice physics and construct a tentative phase diagram of their correlated electrons with two characteristic energy scales $ω^*$ and $Ω$ marking the upper boundary of a low-energy regime with well-developed long-range coherence and the lower boundary of localized spectral weight in the energy space, respectively. In between, there exists a crossover region with emergent but damped quasiparticle excitations. We argue that the presence of two separate energy scales is a generic property of correlated electrons on a…
