Ultrathin MgB2 films fabricated on Al2O3 substrate by hybrid physical–chemical vapor deposition with high Tc and Jc

• Published in: Superconductor science & technology Vol. 24; no. 1; p. 015013
• Main Authors: Zhang, Yuhao, Lin, Zhiyuan, Dai, Qian, Li, Dongyao, Wang, Yinbo, Zhang, Yan, Wang, Yue, Feng, Qingrong
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.01.2011; Institute of Physics
• Subjects: Aluminum oxide; Borides; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Critical currents; Epitaxial growth; Exact sciences and technology; High-tc films; Magnesium compounds; Physics; Properties of type I and type II superconductors; Superconducting films; Superconducting films and low-dimensional structures; Superconductivity; Thin films; Vapor deposition; Ultrathin films; Superconducting thin films; Critical current density; Scanning electron microscopy; Electrical conductivity; Superconducting transitions; Nanostructures; Deposition process; CVD; Thickness; Magnesium boride; High-Tc superconductors; Physical vapor deposition
• ISSN: 0953-2048; 1361-6668
• DOI: 10.1088/0953-2048/24/1/015013

Ultrathin MgB2 superconducting films with a thickness down to 7.5 nm are epitaxially grown on (0001) Al2O3 substrate by a hybrid physical--chemical vapor deposition method. The films are phase-pure, oxidation-free and continuous. The 7.5 nm thin film shows a Tc(0) of 34 K, which is so far the highest Tc(0) reported in MgB2 with the same thickness. The critical current density of ultrathin MgB2 films below 10 nm is demonstrated for the first time as Jc ~ 106 A cm - 2 for the above 7.5 nm sample at 16 K. Our results reveal the excellent superconducting properties of ultrathin MgB2 films with thicknesses between 7.5 and 40 nm on Al2O3 substrate.