Document Type

Journal Article

Publication Details

This article was originally published as: Zhao, Y, Ionescu, M, Roussel, M et al, Superconducting and Microstructural Properties of Two Types of MgB2 Films Prepared by Pulsed Laser Deposition, IEEE Transactions on Applied Superconductivity, June 2005, 15(2), 3261-3264. Copyright IEEE 2005.

Abstract

Significant differences in superconducting and microstructural properties between two types of MgB2 films prepared by pulsed laser deposition were determined. A very high Hc2 T slope of 1.1 T/K was achieved in the in situ film. The Jc Hcurves of the in situ film also show a much weaker field dependence than that of the ex situ film. The magneto-optical (MO)images show that at 4 K the flux penetrates the in situ MgB2 film through random paths, while for the ex situ film, the flux penetration pattern is mostly repeatable, indicating a defect-controlled flux penetration. Microstructural study (transmission electron microscopy and atomic force microscopy) revealed a relatively big grain size in the ex situ film. The correlation between the superconducting properties, microstructure and preparation conditions is discussed with regard to the two types of films.