Quantum Oscillations in the High Pressure Metallic State of Ca$_2$RuO$_4$

TL;DR

This study reports quantum oscillations in the pressure-induced metallic phase of Ca$_2$RuO$_4$, revealing a complex spectrum with light effective masses, indicating a weakly correlated Fermi liquid state.

Contribution

First observation of quantum oscillations in Ca$_2$RuO$_4$ under pressure, linking experimental data with band structure calculations to understand its electronic properties.

Findings

Quantum oscillations observed in pressure-induced metallic Ca$_2$RuO$_4$

Oscillation spectrum is complex and field-dependent

Effective masses suggest a weakly correlated Fermi liquid

Abstract

We present evidence for quantum oscillations in the pressure-induced metallic state of the 4$d$ layered perovskite Ca$_2$RuO$_4$. A complicated oscillation spectrum is observed, which is both temperature and field dependent, with unusually light cyclotron masses in the range of $m^*/m_e$ $\sim$ 0.6 -- 3, suggesting that the pressure-induced metallic state is a weakly correlated Fermi liquid. We compare our observations to band structure calculations within the local spin density approximation, and conclude that some features of the spectrum are a result of non-linear spin splitting effects.