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 ρc/ρab, where ρc is the resistivity along the c axis and ρab 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.

We present the results of point-contact spectroscopy measurements on high-quality epitaxial MgB2 thin films with injected current along the c-axis. The temperature and field dependences of π-band properties with the field parallel to (H||) or perpendicular to (H⊥) the c-axis are investigated in detail. When a magnetic field is applied, either parallel or perpendicular to the c-axis, the density of the quasiparticle state (DOS) of the π-band proliferates quickly with increasing field, while the gap amplitude of the π-band decreases slowly, which is different from the recent theoretical calculations, showing a field dependent competition between the interband scattering and the pair-breaking effects.

The current-voltage (I-V) characteristics of various MgB(2) films have been studied at different magnetic fields parallel to the c axis. At fields mu(0)H between 0 and 5 T, vortex liquid-glass transitions were found in the I-V isotherms. Consistently, the I-V curves measured at different temperatures show a scaling behavior in the framework of quasi-two-dimension (quasi-2D) vortex-glass theory. However, at mu(0)H >= 5 T, a finite dissipation was observed down to the lowest temperature here, T=1.7 K, and the I-V isotherms did not scale in terms of any known scaling law, of any dimensionality. We suggest that this may be caused by a mixture of sigma band vortices and pi band quasiparticles. Interestingly, the I-V curves at zero magnetic field can still be scaled according to the quasi-2D vortex-glass formalism, indicating an equivalent effect of self-field due to persistent current and applied magnetic field.

We have noticed the following misprints in our paper: 1.In Eq. ͑2͒, i is defined asOur conclusions are not affected since all calculations presented in the paper were performed using the correct formulas.