Composition dependence of superconductivity and surface morphology of MgB2 thin films grown by molecular beam epitaxy

✍ Scribed by H. Yamamoto; A. Tsukamoto; H. Hasegawa; K. Saitoh; M. Okada; H. Kitaguchi

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 154 KB
• Volume: 426-431
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2005.01.071

✦ Synopsis

The relationship between the composition and the superconducting properties of Mg x B 2 films fabricated by molecular beam epixay (MBE) were investigated. The Mg x B 2 films-with a composition gradient of Mg and B-were formed on c-plane Al 2 O 3 (0 0 0 1) substrates by controlling the in-plane distribution of the flux rate of Mg on the substrates. It was found that the composition of the films on the substrates, x (in Mg x B 2 ), gradually changed from 0.68 to 2.75. Though the composition was distributed widely, the films showed superconductivity in their whole area. Thin films with a critical temperature of 31-33 K, critical current density of 0.8-1.1 • 10 7 A/cm 2 at 4.2 K, and surface roughness of 2-3 nm were obtained in a wide range of film compositions from stoichiometric to Mg-poor (i.e., x = 0.68-0.96). The films with these properties can be applied for multilayered structures in device applications.