Tunneling spectroscopy of the superconducting state of URu2Si2

TL;DR

This study uses scanning tunneling microscopy with a superconducting tip to investigate the superconducting gap structure of URu2Si2, revealing a V-shaped density of states and gap nodes, indicating unconventional superconductivity.

Contribution

First direct tunneling spectroscopy measurements of URu2Si2's superconducting gap revealing gap nodes and unconventional features using STM with a superconducting tip.

Findings

V-shaped density of states at low energies

Gap nodes present on the Fermi surface

Quasiparticle peaks near the expected BCS gap

Abstract

We present measurements of the superconducting gap of URu$_2$Si$_2$ made with scanning tunneling microscopy (STM) using a superconducting tip of Al. We find tunneling conductance curves with a finite value at the Fermi level. The density of states is V shaped at low energies, and the quasiparticle peaks are located at values close to the expected superconducting gap from weak coupling BCS theory. Our results point to rather opened gap structures and gap nodes on the Fermi surface.