Origin of electronic localization in metal-insulator transition of phase change materials

Tellurium based phase change materials are unique 3D-solids proposed to undergo Anderson type metal-insulator transition. However, the origin of this transition is not unambiguously understood. Here, we report combined high energy resolution photoemission spectroscopy and high k-resolution X-ray diffraction measurements on a reversibly phase switched Ge2Sb2Te5 film. The results resolve the ambiguity between previous spectroscopic data and the proposed theoretical model for the origin of Anderson localization in these materials. Furthermore, by switching between the metallic state to insulating and back to metallic, we probe the electronic structure evolution in the phase change material.