General Rule and Materials Design of Negative Effective U System for High-T_c Superconductivity

TL;DR

This paper proposes a general rule and materials design strategy for negative effective U systems to achieve high-temperature superconductivity, based on microscopic mechanisms involving charge excitation and exchange-correlation effects.

Contribution

It introduces a novel framework for designing high-T_c superconductors by utilizing negative effective U systems in itinerant materials, connecting microscopic mechanisms with practical material design.

Findings

Identifies charge-excitation-induced negative U in s^1/d^9 configurations.

Highlights exchange-correlation-induced negative U in d^4/d^6 configurations.

Proposes a design of T_c-enhancing layers to realize high-T_c superconductivity.

Abstract

Based on the microscopic mechanisms of (1) charge-excitation-induced negative effective U in s^1 or d^9 electronic configurations, and (2) exchange-correlation-induced negative effective U in d^4 or d^6 electronic configurations, we propose a general rule and materials design of negative effective U system in itinerant (ionic and metallic) system for the realization of high-T_c superconductors. We design a T_c-enhancing layer (or clusters) of charge-excitation-induced negative effective $U$ connecting the superconducting layers for the realistic systems.