The Dendritic magnetic avalanches in carbon-free MgB${}_2$ thin films with and without a deposited Au layer

Abstract

From the magneto optics images (MOI), the dendritic magnetic avalanche is known to appear dominantly for thin films of the newly discovered MgB${}_2$. To clarify the origin of this phenomenon, we studied in detail the MOI of carbon-free MgB${}_2$ thin films with and without a deposited gold layer. The MOI indicated carbon contamination was not the main source of the avalanche. The MOI clearly showed that the deposition of metallic gold deposition on top of a MgB${}_2$ thin film improved its thermal stability and suppressed the sudden appearance of the dendritic flux avalanche. This is consistent with the previous observation of flux noise in the magnetization.

9 pages, 4 figeures