Novel electronic junctions in an atomic wire array: interfaces between metallic and charge density wave ordered electronic phases

The Si(111)-(4x1)In atomic wire array is an extremely popular model for one-dimensional electronic systems. It features a reversible, temperature-induced metal insulator transition into a charge density wave (CDW) ordered ground state with (8x2) translational symmetry. Close to the phase transition temperature, both phases can coexist and form novel types of electronic junctions between the metallic (4x1) phase and the insulating CDW-ordered (8x2) phase. Combining scanning tunneling microscopy/spectroscopy (STM/STS) and ab initio molecular dynamics calculations, we explore the microscopic structure of interfaces between distinct electronic phases at the atomic scale. Specific defects allow to modify and control the structure of these electronic interfaces. We explain the atomistic mechanism behind the junction formation and its tunability from first principles.