Combined scanning force microscopy and scanning tunneling spectroscopy of an electronic nano-circuit at very low temperature

TL;DR

This paper presents a combined low-temperature scanning force microscopy and tunneling spectroscopy technique to study superconducting nano-circuits, revealing deviations from BCS theory.

Contribution

It introduces a novel integrated approach for high-stability, low-temperature local probing of nano-circuits combining two microscopy methods.

Findings

Observed deviations from BCS predictions in superconducting nano-circuits

Achieved high stability in tunneling measurements at 60 mK

Enabled spatially-resolved spectroscopic analysis of nano-structures

Abstract

We demonstrate the combination of scanning force microscopy and scanning tunneling spectroscopy in a local probe microscope operating at very low temperature (60 mK). This local probe uses a quartz tuning fork ensuring high tunnel junction stability. We performed the spatially-resolved spectroscopic study of a superconducting nano-circuit patterned on an insulating substrate. Significant deviations from the BCS prediction are observed.