Correlation induced exotic ground states in novel sulfides

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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".