Quasiparticle interference and strong electron-mode coupling in the quasi-one-dimensional bands of Sr 2 RuO 4

Zhenyu Wang, Daniel Walkup, Philip Derry, Thomas Scaffdi, Melinda Rak, Sean Vig, Anshul Kogar, Ilija Zeljkovic, Ali Husain, Luiz H. Santos, Yuxuan Wang, Andrea Damascelli, Yoshiteru Maeno, Peter Abbamonte, Eduardo Fradkin, Vidya Madhavan

Research output: Contribution to journalArticlepeer-review

Abstract

The single-layered ruthenate Sr 2 RuO 4 is presented as a potential spin-triplet superconductor with an order parameter that may break time-reversal invariance and host half-quantized vortices with Majorana zero modes. Although the actual nature of the superconducting state is still a matter of controversy, it is believed to condense from a metallic state that is well described by a conventional Fermi liquid. In this work we use a combination of Fourier transform scanning tunnelling spectroscopy (FT-STS) and momentum-resolved electron energy loss spectroscopy (M-EELS) to probe interaction effects in the normal state of Sr 2 RuO 4 . Our high-resolution FT-STS data show signatures of the β-band with a distinctly quasi-one-dimensional (1D) character. The band dispersion reveals surprisingly strong interaction effects that dramatically renormalize the Fermi velocity, suggesting that the normal state of Sr 2 RuO 4 is that of a 'correlated metal' where correlations are strengthened by the quasi-1D nature of the bands. In addition, kinks at energies of approximately 10 meV, 38 meV and 70 meV are observed. By comparing STM and M-EELS data we show that the two higher energy features arise from coupling with collective modes. The strong correlation effects and the kinks in the quasi-1D bands could provide important information for understanding the superconducting state.

Original languageEnglish (US)
Pages (from-to)799-805
Number of pages7
JournalNature Physics
Volume13
Issue number8
DOIs
StatePublished - Aug 1 2017

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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