MgB2 thin films grown on graphene/Ni–Mo alloy system

• Depositing MgB2 thin films on graphene/Ni–Mo alloy substrate by HPCVD is a completely new method.
• The growth of MgB2 thin films in this system lays a good foundation of depositing MgB2 thick films.
• We directly deposite MgB2 films on graphene(without transferring) which keeps graphene’s original morphology and properties.

200 nm Ni film is coated on 25 μm thick Mo foil, and graphene is grown on the Ni–Mo system by CVD method. After the annealing process of CVD, the Ni/Mo bilayer transforms into Ni–Mo alloy, then we have successfully fabricated MgB2 films on graphene/Ni–Mo alloy system via the hybrid physical–chemical vapor deposition (HPCVD) technique. The transition temperature Tc onset is 38.25 K with a corresponding transition width of 0.75 K. The average thickness of MgB2 films is 200 nm (25% concentration B2H6). The critical current density derives from the magnetization measurement at 5 K is, jc (5 K, 0 T) = 9.6 × 106 A/cm2. We can easily deposite MgB2 on graphene/Ni–Mo alloy system with a lower B2H6 concentration and less gas flow, which lays a good foundation for depositing MgB2 thick films. The graphene in this system is multilayer and with defects, it may act like an intermediary film for the growth of MgB2, or a carbon-doping source.