Correlation induced exotic ground states in novel sulfides

在绝缘体与金属的相边界上出现了大量的新现象，俗称莫特跃迁，是由电子之间的排斥性库仑相互作用引起的。提出的项目旨在确定“绝缘体到金属边界”，主要是在硫化物中，并将这些边界调整到奇异相，特别是在这些相边界附近的非常规金属绝缘体波动可以稳定奇异基态。这种相界已经在一些硫化物如BaFe2S3和GaNb4S8中被观察和研究，而对于硫化物如NiPS3尚未被研究。在这个项目中，主要目标是通过化学取代来探索这种相关诱导的“绝缘体到金属边界”，期望在硫化物中找到奇异的基态。我们从化学取代已知的硫基Mott绝缘体（如BaFe2S3， CsFe2S3）开始，研究它们的电子相图作为取代/掺杂的函数。我们在外加磁场中或通过取代/掺杂寻找量子临界点的存在。我们将探索尚未报道的新型硫化物，特别是在MPS3 （M =过渡金属）结构类型的二维（2D）硫基量子材料领域，其中许多材料已经提出存在，但实验仍需合成和研究，特别是寻找“绝缘体到金属边界”。

Plethora of novel phenomena occur at the phase boundary of insulator to metal, popularly known as Mott-transition caused by the repulsive Coulomb interactions between the electrons. The proposed project aims to identify the "insulator to metal boundary", mainly in sulfides, and to tune these boundaries to the exotic phases, especially unconventional metal-insulator fluctuations near these phase boundaries which can stabilize exotic ground states. Such phase boundaries have been seen and investigated in some sulfides such as BaFe2S3 and GaNb4S8 under pressure, whereas for sulfides such as NiPS3 it is yet to be investigated. Here in this project, the main goal is to explore such correlation-induced "insulator to metal boundaries" by chemical substitutions, anticipating to find exotic ground states in sulfides. We start with chemical substitutions for the known sulfur based Mott insulators, such as BaFe2S3, CsFe2S3 to investigate their electronic phase diagrams as a function of substitution/doping. We search for the presence of quantum critical points either in an applied magnetic field or by substitution/doping. We will explore novel sulfides not yet reported, in particular in the field of two-dimensional (2D) sulfur based quantum materials of the MPS3 (M = transition metals) structure type, where many materials have been proposed to exist but experimentally still have to be synthesized and investigated, especially to search for "insulator to metal boundary".