Structural and Electronic Properties in multilayer (BiSe)$_n$(TiSe$_2$)$_m$ Misfit compounds

The nature of the charge density wave (CDW) transition in 1T-TiSe$_2$ has been hotly debated, and variously described as a simple CDW to the formation of an excitonic insulator. Here we report the synthesis and basic physical properties of the incommensurate layered chalcogenides (BiSe)$_n$(TiSe$_2$)$_m$. Their structure consists of a rock-salt type BiSe layer separated by one or more edge-sharing TiSe$_2$ octahedral layer. These octahedral layers are isomorphic to the layers found in 1T-TiSe$_2$, and thus provide a mechanism to study the electronically driven structural transition in TiSe$_2$ as a function of the number of layers. Structural determinations from electron and x-ray diffraction, using 4/5-D superspace approach, will be presented, and the implications of our results on the understanding of CDW formation in TiSe$_2$ will be discussed. The effects of doping with Cu to observe possible superconducting behavior is also explored.