Spin fluctuations in cuprates as the key to high $T_c$

TL;DR

This paper investigates the role of spin fluctuations in cuprates, demonstrating their importance for understanding anomalous normal state properties and high-temperature superconductivity through a combined theoretical and numerical approach.

Contribution

It introduces a memory-function approach to the spin response in the t-J model, explaining experimental observations and emphasizing the significance of next-nearest-neighbour hopping.

Findings

Explains anomalous scaling at low doping

Reproduces the resonant peak and double dispersion in superconducting phase

Highlights the impact of the next-nearest-neighbour hopping parameter t'

Abstract

Spin fluctuations represent the lowest established energy scale in cuprates and are crucial for the understanding of anomalous normal state properties and superconductivity in these materials. The memory-function approach to the spin response in the t-J model is described. Combined with numerical results for small systems it is able to explain the anomalous scaling at low doping and the crossover to the Fermi-liquid-like behavior in overdoped systems. Within the superconducting phase the theory reproduces the resonant peak and its peculiar double dispersion. Such spin fluctuations are then used as the input for the theory of superconductivity within the t-J model, where we show that an important role is played also by the next-nearest-neighbour hopping parameter $t'$.