Scanning microscopies of superconductors at very low temperatures

TL;DR

This paper reviews scanning tunneling microscopy/spectroscopy techniques for superconductors at very low temperatures, introduces a new method called SAS for local Andreev reflection measurement, and discusses vortex imaging under magnetic fields.

Contribution

It introduces Scanning Andreev Reflection Spectroscopy (SAS), a novel technique for local Andreev reflection analysis in superconductors.

Findings

Demonstrates the SAS method for local spectroscopic measurements.

Shows vortex lattice imaging as a function of magnetic field angle.

Discusses the application of STM/S in superconducting state analysis.

Abstract

We discuss basics of scanning tunneling microscopy and spectroscopy (STM/S) of the superconducting state with normal and superconducting tips. We present a new method to measure the local variations in the Andreev reflection amplitude between a superconducting tip and the sample. This method is termed Scanning Andreev Reflection Spectroscopy (SAS). We also briefly discuss vortex imaging with STM/S under an applied current through the sample, and show the vortex lattice as a function of the angle between the magnetic field and sample's surface.