Local Tunneling Spectroscopy across a Metamagnetic Critical Point in the Bi-layer Ruthenate Sr3Ru2O7

TL;DR

This study uses scanning tunneling microscopy to investigate the electronic signatures of metamagnetic criticality in Sr3Ru2O7, revealing field-dependent spectral features and a novel surface electronic order.

Contribution

It provides new insights into surface electronic structure and critical phenomena in Sr3Ru2O7, highlighting features not explained by simple Stoner theory.

Findings

Field-dependent tunneling spectral features near the Fermi level.

Observation of a pseudo-gap structure over tens of meV.

Detection of a c(2x2) superstructure indicating new surface electronic order.

Abstract

The local spectroscopic signatures of metamagnetic criticality in Sr3Ru2O7 were explored using scanning tunneling microscopy (STM). Singular features in the tunneling spectrum were found close to the Fermi level, as would be expected in a Stoner picture of itinerant electron metamagnetism. These features showed a pronounced magnetic field dependence across the metamagnetic critical point, which cannot be understood in terms of a naive Stoner theory. In addition, a pseudo-gap structure was observed over several tens of meV, accompanied by a c(2x2) superstructure in STM images. This result represents a new electronic ordering at the surface in the absence of any measurable surface reconstruction.