Temperature-doping phase diagram of layered superconductors

TL;DR

This paper investigates how doping affects the superconducting transition temperature in layered materials, deriving a thermodynamic model from microscopic principles and revealing conditions where T_c can be lower than the 2D BKT transition temperature.

Contribution

It derives an effective thermodynamic potential for layered superconductors from a microscopic Hamiltonian, linking doping, coupling, and inter-layer hopping to T_c behavior.

Findings

T_c can be lower than T_BKT under certain parameters

Derived a thermodynamic potential from microscopic Hamiltonian

Analyzed dependence of T_c on doping and inter-layer coupling

Abstract

The superconducting properties of a layered system are analyzed for the cases of zero- and non-zero angular momentum of the pairs. The effective thermodynamic potential for the quasi-2D XY-model for the gradients of the phase of the order parameter is derived from the microscopic superconducting Hamiltonian. The dependence of the superconducting critical temperature T_c on doping, or carrier density, is studied at different values of coupling and inter-layer hopping. It is shown that the critical temperature T_c of the layered system can be lower than the critical temperature of the two-dimensional Berezinskii-Kosterlitz-Thouless transition T_BKT at some values of the model parameters, contrary to the case when the parameters of the XY-model do not depend on the microscopic Hamiltonian parameters.