Formation and consequences of heavy d-electron quasiparticles in Sr3Ru2O7

TL;DR

This study uses angle-resolved photoelectron spectroscopy to investigate the formation of heavy quasiparticles in Sr3Ru2O7, revealing a low-energy scale linked to quantum criticality and hybridization effects.

Contribution

It provides direct experimental evidence of heavy quasiparticle formation and their momentum-dependent hybridization in Sr3Ru2O7, connecting electronic structure to quantum critical behavior.

Findings

Heavy quasiparticles confined within <6 meV energy range.

Energy scale matches thermodynamic quantum criticality scale.

Renormalization varies with momentum and correlates with hybridization.

Abstract

We report angle-resolved photoelectron spectroscopy measurements of the quantum critical metal Sr3Ru2O7 revealing itinerant Ru 4d-states confined over large parts of the Brillouin zone to an energy range of < 6 meV, nearly three orders of magnitude lower than the bare band width. We show that this energy scale agrees quantitatively with a characteristic thermodynamic energy scale associated with quantum criticality and illustrate how it arises from the hybridization of light and strongly renormalized, heavy quasiparticle bands. For the largest Fermi surface sheet we find a marked k-dependence of the renormalization and show that it correlates with the Ru 4d - O 2p hybridization.