Transport and magnetic properties of fully-epitaxial superconducting NbN/half-metallic Heulser alloy Co₂MnSi bilayer films

Abstract

  Fully-epitaxial NbN/Co₂MnSi bilayer films were grown on MgO(001) single crystalline substrates by a sputter technique. Structural, electric transport and magnetic properties were investigated for the fabricated films. The resulting NbN/Co₂MnSi bilayer films show superconducting critical temperature T_c was of 16.0 K and the saturation magnetization M_s at room temperature was of 790 emu/cm³. The electric resistivity of the fabricated films was also measured under magnetic fields and the upper critical field B_c2 was estimated to beB_c2 > 30 T in the case of the applied magnetic field parallel to the MgO(001) single crystalline substrate. In addition, NbN/Co₂MnSi junctions were made by an electron-beam lithography technique. The enhancement of a zero-bias conductance peak (ZBCP) was observed in differential conductance in the NbN/Co₂MnSi junctions. The ZBCP disappeared above T_c = 16.0 K of superconducting NbN films.