Microscopic description of insulator-metal transition in high-pressure oxygen

Abstract

Unusual metallic states involving breakdown of the standard Fermi-liquid picture of long-lived quasiparticles in well-defined band states emerge at low temperatures near correlation-driven Mott transitions. Prominent examples are ill-understood metallic states in $d$- and $f$-band compounds near Mott-like transitions. Finding of superconductivity in solid O${}_2$ on the border of an insulator-metal transition at high pressures close to 96~GPa is thus truly remarkable. Neither the insulator-metal transition nor superconductivity are understood satisfactorily. Here, we undertake a first step in this direction by focussing on the pressure-driven insulator-metal transition using a combination of first-principles density-functional and many-body calculations. We report a striking result: the finding of an orbital-selective Mott transition in a pure $p$-band elemental system. We apply our theory to understand extant structural and transport data across the transition, and make a specific two-fluid prediction that is open to future test. Based thereupon, we propose a novel scenario where soft multiband modes built from microscopically coexisting itinerant and localized electronic states are natural candidates for the pairing glue in pressurized O${}_2$.

8 pages, 6 figures

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Cited by in corpus (3)

• Bandwidth controlled insulator-metal transition in BaFe${}_2$S${}_3$: A Mössbauer study under pressure
• Hund's metal regimes and orbital selective Mott transitions in three band systems
• The role of the nominal iron content in the structural, compositional and physical properties of BaFe${}_{2+\delta }$S${}_3$