Ferromagnetic spin fluctuation induced superconductivity in Sr_2RuO_4

TL;DR

This paper presents a first-principles model explaining triplet superconductivity in Sr_2RuO_4 driven by ferromagnetic spin fluctuations, aligning well with experimental data on critical temperature and electronic properties.

Contribution

It introduces a quantitative, first-principles based model linking ferromagnetic spin fluctuations to triplet superconductivity in Sr_2RuO_4, addressing experimental discrepancies.

Findings

Effective mass renormalization matches experiments

Superconducting order parameters are similar across Fermi surface sheets

Model explains Fermi surface topology discrepancies

Abstract

We propose a quantitative model for triplet superconductivity in Sr_2RuO_4 based on first principles calculations for the electronic structure and magnetic susceptibility. The superconductivity is due to ferromagnetic spin fluctuations, that are strong at small wave vectors. The calculated effective mass renormalization, renormalized susceptibility, and superconducting critical temperature are all in good agreement with experiment. The most stable superconducting solution has order parameters of comparable magnitude on all three sheets of the Fermi surface. We also propose an explanation of the discrepancy between the Fermi surface topology observed in the photoemission and in de Haas-van Alphen experiments.