High critical current density under magnetic fields in as-grown MgB2 thin films deposited by molecular-beam epitaxy

As-grown MgB2 thin films were prepared by a MBE method under the conditions of low temperature, low deposition rate and high vacuum for applications in electric devices. The MgB2 thin films deposited on MgO and Ti buffered ZnO substrates have considerably higher Jc under magnetic fields among MgB2 thin films reported before. The value of Jc for the MgB2 thin film deposited on Ti buffered ZnO has been 5.8 x 105 A cm-2 at 10 K, 5 T in the magnetic field applied parallel to the c axis. In the angular dependence of Jc, the peak of Jc attributable to c-axis-correlated pinning centres has been observed when the magnetic field was applied parallel to the c axis. (rapid communication)