Competing orders and interlayer tunneling in cuprate superconductors: A finite-temperature Landau theory

We propose a finite-temperature Landau theory that describes competing orders and interlayer tunneling in cuprate superconductors as an important extension to a corresponding theory at zero temperature [Chakravarty et at., Nature 428, 53 (2004)], where the superconducting transition temperature T, is defined in three possible ways as a function of the zero-temperature order parameter. For given parameters, our theory determines T, without any ambiguity. In mono- and double-layer systems we discuss the relation between the zero-temperature order parameter and the associated transition temperature in the presence of competing orders, and draw a connection to the puzzling experimental fact that the pseudogap temperature is much higher than the corresponding energy scale near optimum doping. Applying the theory to multilayer systems, we calculate the layer-number dependence of T-c In a reasonable parameter space the result turns out to be in agreement with experiments.