On quantum nature of charge carriers in pseudogap state of underdoped cuprate HTS

It is assumed that the transition of the CuO2 plane to the metallic behavior in the underdoped (UD) pseudogap-state HTSC cuprates at lowering temperature T≤* (Psh) is caused by quantum diffusion predicted by A.F. Andreev and I.M. Lifshitz for 'defectons' in 1969. The features of the pseudogap state are determined only by the properties of the CuO2 plane and the doping concentration Psh. As the temperature decreases, T≤TAL(Psh), a universal line TAL(Psh)=815psh appears in the general magnetic phase diagram. The line describes the transition of the plane into the '2D vortex metal' state with mobile charge carriers (2D) vortices consistent with antiferromagnetism of the CuO2 plane. The phase diagram of states has been platted for the UD single crystal YBaCu3Oy with the line TAL(psh)≤T* (psh) which is consistent with the known experimental data for other UD cuprate HTSCs