Growth of superconducting MgB2 thin films via postannealing techniques

Abstract

We report the effect of annealing on the superconductivity of MgB2 thin films as functions of the postannealing temperature in the range from 700 C to 950 C and of the postannealing time in the range from 30 min to 120 min. On annealing at 900 C for 30 min, we obtained the best-quality MgB2 films with a transition temperature of 39 K and a critical current density of ~ 10^7 A/cm^2. Using the scanning electron microscopy, we also investigated the film growth mechanism. The samples annealed at higher temperatures showed the larger grain sizes, well-aligned crystal structures with preferential orientations along the c-axis, and smooth surface morphologies. However, a longer annealing time prevented the alignment of grains and reduced the superconductivity, indicating a strong interfacial reaction between the substrate and the MgB2 film.

7 pages, 4 figures included

References in corpus (2)

• Two-Band Superconductivity in MgB2
• Universal scaling of the Hall resistivity in MgB2 superconductors

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• Advances in point-contact spectroscopy: two-band superconductor MgB2 (A review)
• Comparative study of in situ and ex situ MgB2 films deposited by pulsed laser deposition
• Critical flux pinning and enhanced upper-critical-field in magnesium diboride films
• Flux Noise in MgB2 Thin Films