A first principles investigation of cubic BaRuO$_3$: A Hund's metal

TL;DR

This study uses advanced computational methods to analyze cubic BaRuO$_3$, revealing a spin-frozen, non-Fermi liquid state at high temperatures that precedes magnetic ordering.

Contribution

It provides the first detailed first-principles investigation of cubic BaRuO$_3$, highlighting the spin-frozen phase and non-Fermi liquid behavior driven by Hund's coupling.

Findings

Cubic BaRuO$_3$ is in a spin-frozen state above the ferromagnetic transition.

Strong Hund's coupling suppresses Fermi liquid coherence.

The system exhibits non-Fermi liquid behavior with a wide temperature range of spin-frozen phase.

Abstract

A first-principles investigation of cubic-BaRuO$_3$, by combining density functional theory with dynamical mean-field theory and a hybridization expansion continuous time quantum Monte-Carlo solver, has been carried out. Non-magnetic calculations with appropriately chosen on-site Coulomb repulsion, $U$ and Hund's exchange, $J$, for single-particle dynamics and static susceptibility show that cubic-BaRuO$_3$ is in a spin-frozen state at temperatures above the ferromagnetic transition point. A strong red shift with increasing $J$ of the peak in the real frequency dynamical susceptibility indicates a dramatic suppression of the Fermi liquid coherence scale as compared to the bare parameters in cubic-BaRuO$_3$. The self-energy also shows clear deviation from Fermi liquid behaviour that manifests in the single-particle spectrum. Such a clean separation of energy scales in this system provides scope for an incoherent spin-frozen (SF) phase, that extends over a wide temperature range, to manifest in non-Fermi liquid behaviour and to be the precursor for the magnetically ordered ground state.