Real-time observation of vortex lattices in a superconductor by electron microscopy

Abstract

THE dynamic behaviour of the quantized vortices of magnetic flux that penetrate type II superconductors, and specifically their interaction with pinning sites, is a topic of both scientific and technological interest, particularly since the discovery of high-transition-temperature (high- Tc) superconductors1. Until now, however, it has not been possible to study this behaviour in 'real time'. The Bitter technique2, scanning tunnelling microscopy3 and scanning electron microscopy4 have so far provided only static images, whereas a magneto-optical technique that provides time-resolved information5 does not resolve individual vortices. Here we report the real-time observation of vortices in a thin film of niobium, using the technique of Lorentz microscopy6. The coherent and penetrating beam of a recently developed 300-kV field-emission electron microscope6 allows us to observe, at 30 frames per second, the motion of thermally activated vortices, and their response to an applied magnetic field.