Spin-Orbit-Induced Orbital Excitations in Sr2RuO4 and Ca2RuO4: A Resonant Inelastic X-ray Scattering Study

TL;DR

This study uses high-resolution RIXS and X-ray absorption to investigate how spin-orbit coupling influences orbital excitations in Sr2RuO4 and Ca2RuO4, shedding light on their electronic structures and ground states.

Contribution

It provides the first detailed analysis of spin-orbit-induced orbital excitations in these materials using RIXS and a minimal model.

Findings

Spin-orbit coupling significantly affects orbital excitations.

Orbital hybridization with oxygen p-orbitals was characterized.

Implications for Mott and superconducting states were discussed.

Abstract

High-resolution resonant inelastic X-ray scattering (RIXS) at the oxygen K-edge has been used to study the orbital excitations of Ca2RuO4 and Sr2RuO4. In combination with linear dichroism X-ray absorption spectroscopy, the ruthenium 4d-orbital occupation and excitations were probed through their hybridization with the oxygen p-orbitals. These results are described within a minimal model, taking into account crystal field splitting and a spin-orbit coupling \lambda_{so}=200~meV. The effects of spin-orbit interaction on the electronic structure and implications for the Mott and superconducting ground states of (Ca,Sr)2RuO4 are discussed.