Anisotropic transport properties in tilted c-axis MgB₂ thin films

We report on superconducting magnesium diboride MgB₂ thin films grown on both YSZ and MgO substrates, with two different orientations, namely [110] and [211]. MgB₂ off-axis growth mode (namely, with the c-axis tilted with respect to the film surface's normal) is achievable on these substrates. Depending on the type and orientation of the substrate, tilting angle can be varied. As a consequence of tilted growth, anisotropic transport properties are observed. In very thin films, resistance measurements provide an estimate of the resistivity anisotropic ratio ρ_c/ρ _ab, where ρ_c is the resistivity along the c axis and ρ_ab is the in-plane resistivity. All these findings clearly demonstrate that tilted MgB₂ films offer new exciting possibilities to both investigate intrinsic fundamental properties of MgB₂ and to explore possible applications in planar superconducting devices.