Evolution of the charge carrier properties and electronic correlations in layered organic metals near the Mott metal-insulator transition

莫特跃迁是正常金属中最基本的相关性驱动的不稳定性之一。尽管进行了广泛的研究，但仍有重要的未解决的问题和悬而未决的问题，特别是关于在定义良好的模型系统中绝缘状态附近的金属基态的实验研究。在这个项目中，我们加入了来自实验和理论物理以及材料科学的专家来解决这些问题。我们将采用kappa型有机电荷转移盐作为具有带宽控制Mott不稳定性的准二维电子模型系统，用于跟踪相图中金属/绝缘体共存区域以及邻近均质金属态中载流子关键特征的演变。特别是，我们将研究(i)相关诱导的有效质量的重整化，（ii）费米表面的精确几何和拓扑结构，以及（iii）电荷输运的相干性。在定义良好的模型系统中对这些特性的系统研究将为现有的莫特金属-绝缘体过渡理论提供重要的检验。该项目的一个关键目标是解开电荷、自旋和晶格自由度对金属绝缘体不稳定性的贡献。这个问题将通过研究具有不同几何挫折、磁相互作用和晶格无序强度的kappa型盐来解决。具有不同阴离子的bett - ttf盐特别适合于研究几何挫折效应，而具有局部磁矩的bett - ttf盐可以获得电子相关和磁相互作用之间的相互作用。通过研究BEDT-TTF盐的氘化对载流子性质的影响和追踪这些盐中乙烯基无序的影响，将探讨电子态与晶格自由度的耦合。解决上述问题的主要实验探索将是磁量子振荡、半经典各向异性磁输运和电阻率各向异性。通过准静水压力和“化学压力”对材料进行微调，可以实现电子基态相对于金属-绝缘体边界的精确控制。参与该项目的理论团队将利用准二维金属中的高场磁输运理论以及相分离电子介质中的电荷输运理论，对实验结果进行定量分析。进一步发展（磁子）输运理论在相关的部分提出的实验计划。获得高质量的kappa型盐单晶对计划项目的成功至关重要。这种晶体的制备和表征将由项目中经验丰富的材料科学团队进行。

The Mott transition is one of the most fundamental correlation-driven instabilities in normal metals. Despite extensive studies, there are important unresolved problems and open questions, in particular regarding the experimental study of the metallic ground state in the immediate vicinity of the insulating state in well-defined model systems. Within this project, we join experts from experimental and theoretical physics and materials science to tackle these problems. We will employ kappa-type organic charge transfer salts as quasi-2D electronic model systems with bandwidth-controlled Mott instability for tracking the evolution of key characteristics of the charge carriers in the metal/insulator coexistence region of the phase diagram as well as in the neighboring homogeneous metallic state. In particular, we will study (i) the correlation-induced renormalization of the effective mass, (ii) the exact geometry and topology of the Fermi surface, and (iii) the coherence of charge transport. The systematic study of these characteristics in well-defined model systems will provide a crucial test for the existing theories of the Mott metal-insulator transition.A key objective of the project is the disentanglement of contributions of charge, spin, and lattice degrees of freedom to the metal-insulator instability. This problem will be addressed by studying kappa-type salts with different strength of geometrical frustration, magnetic interactions, and lattice disorder. The salts of BEDT-TTF with different anions are particularly suited for studying the effects of geometrical frustration, while BETS salts with localized magnetic moments give access to the interplay between electronic correlations and magnetic interactions. The coupling of the electronic state to lattice degrees of freedom will be probed by studying the influence of deuteration of BEDT-TTF salts on the charge carrier properties and by tracing the impact of ethylene-group disorder in these salts.The main experimental probes for addressing the above issues will be magnetic quantum oscillations, semiclassical anisotropic magnetotransport, and resistivity anisotropy. A precise control of the electronic ground state with respect to the metal-insulator boundary will be realized by fine-tuning materials with quasi-hydrostatic pressure as well as "chemical pressure". A quantitative analysis of the experimental results will be carried out by the theory team involved in the project using the state-of-the-art theory of high-field magnetotransport in quasi-2D metals as well as of the charge transport in phase-separated electronic media. Further development of the (magneto)transport theory in the segments related to the proposed experiments is planned.The availability of top-quality single crystals of kappa-type salts is crucial for the success of the planned project. The preparation and characterization of such crystals will be carried out by the experienced materials science team of the project.