Superconductivity in Quantum Complex Matter: the Superstripes Landscape

TL;DR

This paper discusses the evolution of superconductivity theory from homogeneous metals to complex quantum systems with nanoscale inhomogeneity, multiple Fermi surfaces, and gaps, highlighting recent advances and hot topics in the field.

Contribution

It provides an overview of recent developments in understanding superconductivity in complex quantum matter, emphasizing the role of inhomogeneity, multigap phenomena, and mesoscopic effects.

Findings

Superconductivity in complex systems involves nanoscale inhomogeneity and multiple gaps.

Recent research highlights the importance of polarons, strain, and multigap effects.

New perspectives in high-temperature superconductivity and mesoscopic quantum engineering.

Abstract

While in XX century the theory of superconductivity has focused on a homogeneous metal with a rigid lattice which can be reduced to a single effective conduction band in the dirty limit. Today in the XXI century, the physics of superconductivity is focusing on complexity of quantum matter where novel quantum functionalities with lattice inhomogeneity at nanoscale (between 1 nm and 100 nm) and at mesoscopic scale (in the range 100-10000 nm), where the electronic structure need to be described by multiple Fermi surfaces and multiple gaps in the superconducting phase in the clean limit. The present issue of Journal of superconductivity and Novel magnetism collects papers presented at the International Conference Superstripes 2019 which was held on June 23-29, 2019, in Ischia Island, Italy. The series of Stripes conference started on Dec 8 1996 and it has contributed to scientific advances in the new physics of superconductivity in quantum complex systems in these last 23 years where polarons, strain, multigap superconductivity, exchange interaction between condensates, granular superconductivity and percolation play a key role. The articles collected in this issue cover hot topics of the new quantum physics of complex matter including the mechanism of high temperature superconductivity, complex magnetic orders and orbital physics in strongly correlated materials which have been growing rapidly in these last two years opening new perspectives also in mesoscopic quantum engineering.