Reversible Insulator-Metal Transition by Chemical Doping and Dedoping of a Mott Insulator

摘要

The chemical carrier doping of molecular Mott insulators has been poorly investigated to date due to its difficulty.In this study,iodine doping of a molecular Mott insulator,lithium phthalocyanine crystallized in the x-form(x-LiPc),was performed to obtain metallic x-LiPcI.Crystal structure analysis revealed that iodine atoms penetrated channels of x-LiPc and formed one-dimensional chains.The Raman spectroscopy of x-LiPcI indicated the existence of linear I_5~-,demonstrating a transition from a half-filled band of the Mott insulating state to a 2/5-filled band of the metallic state.Electrical resistivity measurements confirmed the metallic nature of x-LiPcI,whereas a thermally activated behavior was observed for pristine x-LiPc.Furthermore,the x-LiPc Mott insulator was reproduced by dedoping iodine from x-LiPcI,suggesting that the electronic state can be reversibly tuned between the Mott insulating and metallic states by chemical doping and dedoping.