Spin-fluctuation mechanism of superconductivity in cuprates

TL;DR

This paper develops a theory for superconductivity in cuprates based on the t-J model, highlighting the dominant role of spin fluctuations and their influence on the critical temperature T_c.

Contribution

It introduces a spin-fluctuation based mechanism within the t-J model, linking T_c variation to spin dynamics and next-nearest-neighbor hopping t' in cuprates.

Findings

Superconductivity is primarily driven by spin fluctuations.

T_c is limited by the spin-fluctuation scale Γ.

Variation in T_c among cuprates correlates with t' hopping parameter.

Abstract

The theory of superconductivity within the t-J model, as relevant for cuprates, is developed. It is based on the equations of motion for projected fermionic operators and the mode-coupling approximation for the self-energy matrix. The dynamical spin susceptibility at various doping is considered as an input, extracted from experiments. The analysis shows that the superconductivity onset is dominated by the spin-fluctuation contribution. We show that T_c is limited by the spin-fluctuation scale $\Gamma$ and shows a pronounced dependence on the next-nearest-neighbor hopping t'. The latter can offer an explanation for the variation of T_c among different families of cuprates.