Formation of heavy d-electron quasiparticles in Sr3Ru2O7

Milan P Allan ,Mark H Fischer ,Z.‐X Shen ,Kim Ea ,R S Perry ,E D L Rienks ,Kyle Shen ,Alan Tennant ,Jean-François Mercure ,Craig J Fennie ,M A Wang ,A P Mackenzie ,P D C King ,Michael J Lawler ,J Fink ,S Thirupathaiah ,Johannes Voss ,Jinho Lee,E Rozbicki ,W Meevasana ,Anna Tamai ,F Baumberger

doi:10.1088/1367-2630/15/6/063029

Abstract

The phase diagram of Sr3Ru2O7 shows hallmarks of strong electron correlations despite the modest Coulomb interaction in the Ru 4d shell. We use angle-resolved photoelectron spectroscopy measurements to provide microscopic insight into the formation of the strongly renormalized heavy d-electron liquid that controls the physics of Sr3Ru2O7. Our data reveal 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 a combination of back-folding due to a structural distortion and the hybridization of light and strongly renormalized, heavy quasiparticle bands. The resulting heavy Fermi liquid has a marked k-dependence of the renormalization which we relate to orbital mixing along individual Fermi surface sheets.

Highlights

The existence of the low-energy scale in Sr3Ru2O7 mentioned above is supported by recent transport and entropy data [2, 5]
Relevant in the context of this paper is the observation of a maximum in the zero-field electronic specific heat Cel(T )/T near 8 K. The position of this maximum can be suppressed continuously in an external field, terminating in a logarithmic divergence at the putative quantum critical end point [5]. This suggests that criticality in Sr3Ru2O7 is driven by the suppression of a single, low-energy scale that persists in zero field
The low-energy electronic structure of Sr3Ru2O7 is summarized in figure 1(a) where we show an experimental Fermi surface with a model of the low-energy quasiparticle dispersion that spans the entire Brillouin zone

Summary

Introduction

The existence of the low-energy scale in Sr3Ru2O7 mentioned above is supported by recent transport and entropy data [2, 5]. The low-energy electronic structure of Sr3Ru2O7 is summarized in figure 1(a) where we show an experimental Fermi surface with a model of the low-energy quasiparticle dispersion that spans the entire Brillouin zone.

Results

Conclusion