Phase lamination in a t–J bilayer at finite temperature

• Phase diagram of a bilayered t–Jt–J model in n–Tn–T space is studied.
• Phase lamination can occur at a low doping density and temperature regime.
• Phase lamination can raise the superconducting transition temperature.

A bilayered t–Jt–J model is investigated with a slave boson mean field theory. A spontaneous phase lamination (PL) into a layer dominated by antiferromagnetism (AFM) and a layer dominated by superconductivity (SC) is found at a low doping density and low temperature regime. Raising the temperature removes the PL and SC, turns the system into a homogeneously antiferromagnetic (AF) bilayer, and eventually a homogeneously paramagnetic bilayer at high temperature. The PL circumvents the competition between AFM and SC, and may result in a higher superconducting transition temperature. The density of states of low energy single particle excitation in the homogeneously AF state at intermediate temperature is reduced by the AF scattering. The relation between this study and the bilayered superconducting cuprates is discussed.