Superconducting gap structure and pinning in disordered MgB2 films
arXiv:cond-mat/0309589 · doi:10.1088/0953-2048/17/5/052
Abstract
We have performed a comparative study of two thin films of magnesium diboride (MgB2) grown by different techniques. The critical current density at different temperatures and magnetic fields was evaluated from magnetisation curves, the structure of superconducting order parameter was obtained from point-contact spectroscopy, and the scattering rates were evaluated by fitting the temperature dependent normal-state resistivity to the two-band model. The films have similar critical temperatures close to 39 K, but the upper critical fields were different by a factor of 2 (5.2T and 2.5 T at 20 K). We have found that the film with higher Hc2 also had stronger scattering in the sigma band and smaller value of the superconducting gap in this band. As the scattering in sigma band is primarily due to the defects in boron plane, our results are consistent with the assumption that disordering the boron planes leads to enhanced Hc2 and better pinning properties in magnetic field.
Paper presented at EUCAS'03
References in corpus (20)
- Beyond Eliashberg superconductivity in MgB2: anharmonicity, two-phonon scattering, and multiple gaps
- Enhancement of the critical current density and flux pinning of MgB2 superconductor by nanoparticle SiC doping
- Enhancement of the upper critical field by nonmagnetic impurities in dirty two-gap superconductors
- Evidence for two superconducting energy gaps in MgB2 by point-contact spectroscopy
- Thin Film Magnesium Boride Superconductor with Very High Critical Current Density and Enhanced Irreversibility Field
- Two Gap State Density in MgB: A True Bulk Property or A Proximity Effect?
- In situ epitaxial MgB2 thin films for superconducting electronics
- Two-gap superconductivity in MgB: clean or dirty?
- Enhancement of the high-field critical current density of superconducting MgB2 by proton irradiation
- Effect of magnetic and non-magnetic impurities on highly anisotropic superconductivity
- Probing Spin Polarization with Andreev Reflection: A Theoretical Basis
- High Critical Current Density and Improved Irreversibility Field in Bulk MgB2 Made By A Scaleable, Nanoparticle Addition Route
- Specific heat of single crystal MgB_2: a two-band superconductor with two different anisotropies
- de Haas-van Alphen effect in single crystal MgB_2
- Thickness dependence of the properties of epitaxial MgB2 thin films grown by hybrid physical-chemical vapor deposition
- Growth mechanism of superconducting MgB2 films prepared by various methods
- The structure of the superconducting gap in MgB2 from point-contact spectroscopy
- Superconducting energy gap distribution in c-axis oriented MgB thin film from point contact study
- Independent determination of the two gaps by directional point-contact spectroscopy in MgB_2 single crystals
- Effective Vortex Pinning in MgB2 thin films