Electron-beam-induced shift in the apparent position of a pinned vortex in a thin superconducting film

TL;DR

This paper develops a quantitative theory to analyze how an electron beam causes a measurable shift in the apparent position of a vortex in a superconducting film, aiding in vortex visualization techniques.

Contribution

It introduces a theoretical framework for calculating vortex displacement due to electron beam heating using four different thermal power distribution models.

Findings

Displacement depends on beam position relative to vortex

Different thermal models yield consistent displacement estimates

Theory supports improved vortex imaging in superconducting devices

Abstract

When an electron beam strikes a superconducting thin film near a pinned vortex, it locally increases the temperature-dependent London penetration depth and perturbs the circulating supercurrent, thereby distorting the vortex's magnetic field toward the heated spot. This phenomenon has been used to visualize vortices pinned in SQUIDs using low-temperature scanning electron microscopy. In this paper I develop a quantitative theory to calculate the displacement of the vortex-generated magnetic-flux distribution as a function of the distance of the beam spot from the vortex core. The results are calculated using four different models for the spatial distribution of the thermal power deposited by the electron beam.