Renormalized mean-field t-J model of high-Tc superconductivity: comparison with experiment

TL;DR

This paper employs an advanced renormalized mean-field theory for the t-J model to study high-Tc superconductivity, achieving good agreement with experimental data and analyzing the effects of different Hamiltonian modifications on the superconducting state.

Contribution

It introduces an improved RMFT approach for the t-J model and compares various Hamiltonian forms, highlighting the impact of three-site terms on superconductivity.

Findings

Doping dependence of the SC gap matches experiments for BSCCO and LSCO.

The dispersion relation aligns with ARPES data and other theoretical studies.

Three-site terms significantly suppress superconductivity.

Abstract

Using an advanced version of the renormalized mean-field theory (RMFT) for the t-J model, we examine spin-singlet superconducting (SC) state of $d_{x^2 - y^2}$-symmetry. Overall doping dependence of the SC gap magnitude is in good agreement with experimental results for $\text{Bi}_{2}\text{Sr}_{2}\text{Ca} \text{Cu}_2 \text{O}_{8 + \delta}$ (BSCCO) and $\text{La}_{2-x}\text{Sr}_{x}\text{Cu} \text{O}_{4}$ (LSCO) compounds at the optimal doping and in the overdoped regime. We also calculate the dispersion relation for the Bogoliubov quasiparticles and compare our findings both with the angle resolved photoemission data for the cuprates, as well as with the variational Monte Carlo and other mean-field studies. Within the method proposed by Fukushima [cf. Phys. Rev. B \textbf{78}, 115105 (2008)], we analyze different forms of the t-J Hamiltonian, i.e. modifications caused by the form of exchange interaction, and by the presence of three-site terms. It is shown that although the former has a small influence, the latter suppresses strongly the superconductivity. We also analyze the temperature dependence of the gap magnitude and compare the results with those of the recently introduced finite-temperature renormalized mean-field theory (TRMFT) of Wang et al. [cf. Phys. Rev. B \textbf{82}, 125105 (2010)].