Multi-orbital physics in Fermi liquids prone to magnetic order

TL;DR

This paper investigates the complex multi-orbital physics and magnetic responses in strontium ruthenate compounds, combining first-principles calculations with mean-field theory to understand their correlated electronic structures and metamagnetic behavior.

Contribution

It introduces a comprehensive approach integrating band-structure theory and slave boson methods to analyze spin-orbit coupling and correlations in Sr$_2$RuO$_4$ and Sr$_3$Ru$_2$O$_7$, revealing new insights into their magnetic properties.

Findings

Renormalized quasiparticle bands match experimental data.

Detailed analysis of Sr$_3$Ru$_2$O$_7$'s metamagnetic response.

Identification of multi-orbital effects and their dependence on magnetic field angle.

Abstract

The interplay of spin-orbit-coupling and strong electronic correlations is studied for the single-layer and the bilayer compound of the strontium ruthenate Ruddlesden-Popper series by a combination of first-principles band-structure theory with mean-field rotationally invariant slave bosons. At equilibrium strongly renormalized (spin-orbit-split) quasiparticle bands are traced and a thorough description of the low-energy regime for the nearly ferromagnetic bilayer system in accordance with experimental data is presented. The metamagnetic response of Sr$_3$Ru$_2$O$_7$ in finite magnetic field $H$ is verified and a detailed analysis of the underlying correlated electronic structure provided. Intriguing multi-orbital physics on both local and itinerant level, such as e.g. competing paramagnetic and diamagnetic contributions, is observed with important differences depending on the magnetic-field angle $\theta$ with the crystallographic c axis.