Magnetic force microscopy measurement of the penetration depth in superconductors from Meissner repulsion

TL;DR

This paper introduces a local measurement technique for the penetration depth in superconductors using magnetic force microscopy, providing a new way to analyze the Meissner response with high precision.

Contribution

The authors develop an analytical model to extract the penetration depth from MFM measurements, which is unaffected by tip width and applicable to various tips.

Findings

The method accurately measures the penetration depth in YBa2Cu3O6+x crystals.

Results agree well with previous measurements, validating the approach.

The technique is robust against tip geometry variations.

Abstract

We report a method to locally measure the penetration depth $\lambda$ in a superconductor by detecting the diamagnetic response using magnetic force microscopy (MFM). We extract $\lambda$ by fitting the height dependence of the levitation force in the Meissner state using an analytical model that approximates the MFM tip as a single-domain, truncated conical shell. We demonstrate on two YBa$_2$Cu$_3$O$_{6+x}$ single crystals with two MFM tips that the obtained values agree well with previous results. This approach is not affected by the tip width and can be applied to similar but not identical tips.