Magnetic anisotropy of thin sputtered MgB2 films on MgO substrates in   high magnetic fields
  We investigated the magnetic anisotropy ratio of thin sputtered polycrystalline MgB2 films on MgO substrates. Using high magnetic field measurements, we estimated an anisotropy ratio of 1.35 for T=0 K with an upper critical field of 31.74 T in the parallel case and 23.5 T in the perpendicular case. Direct measurements of a magnetic-field sweep at 4.2 K show a linear behavior, confirmed by a linear fit for magnetic fields perpendicular to the film plane. Furthermore, we observed a change of up to 12% of the anisotropy ratio in dependence of the film thickness. 
Savio Fabretti and Inga-Mareen Imort and Timo Kuschel and Thomas Dahm   and Veerendra K. Guduru and Uli Zeitler and Andy Thomas
cond-mat.mtrl-sci