CDW and Similarity of the Mott Insulator-to-Metal Transition in Cuprates with the Gas-to-Liquid-Liquid Transition in Supercooled Water
New advances in X-ray diffraction, extended X-ray absorption fine structure (EXAFS), and X-ray absorption near edge structure (XANES) using synchrotron radiation have now provided compelling evidence for a short-range charge density wave phase (CDW) called striped phase in the CuO2 plane of all cuprate high-temperature superconductors. The CDW is associated with a bond order wave (BOW) and an orbital density wave (ODW) forming nanoscale puddles which coexist with superconducting puddles below T (c) . The electronic CDW crystalline phase occurs around the hole doping 0.125 between the Mott charge transfer insulator and the 2D metal. The Van der Waals (VdW) theoretical model for a liquid of anisotropic extended objects proposed for supercooled water is used to describe the following: (a) the underdoped regime as a first spinodal regime of a "slightly doped charge transfer Mott insulator puddles coexisting with the striped polaronic CDW puddles;nd (b) the optimum doping regime as a second spinodal regime where striped polaronic CDW puddles coexist with the normal 2D metal puddles. This complex phase separation with three competing phases depends on the strength of the anisotropic electron-phonon interaction that favours the formation striped polaronic CDW phase.