The Phase Diagram of High-Tc Cuprates

Abstract

The detailed structure of the $T \times doping$ phase diagram of hole doped High-Tc superconducting cuprates is investigated from the perspective of a recently proposed comprehensive theory for these materials. Our theory is compared to Anderson's RVB theory for High-$T_c$ cuprates and it is demonstrated that the ground-eigenstate of our theory's Hamiltonian is a RVB-like state. From the Hamiltonian we derive the thermodynamic potential, as a function of convenient order parameters, through a method whose stability is carefully demonstrated. From this, we obtain analytic expressions for the transition lines delimiting the N\'eel phase, $T_N(x)$, the Spin-Glass phase, $T_{g}(x)$ and the CDW Charge Ordered phase, $T_{co}(x)$. These results, along with the previously derived expressions for the transition lines delimiting the Superconducting phase, $T_C(x)$, the Pseudogap and Strange Metal phases, $T^*(x)$ and the Fermi Liquid phase, $T_{FL}(x)$ are in excellent agreement with the experimental data from the cuprates. Our study reveals, in particular, the complementary role, which is played by the mechanisms responsible for the onset of superconducting (SC) and Spin-Glass (SG) phases in these materials. The absence of SG phases in electron doped High-Tc superconducting cuprates, strongly suggests a different SC mechanism should operate in those materials