Direct evidence for two-band superconductivity in MgB_2 single crystals from directional point-contact spectroscopy in magnetic fields

Abstract

We present the results of the first directional point-contact spectroscopy experiments in high-quality MgB_2 single crystals. Due to the directionality of the current injection into the samples, the application of a magnetic field allowed us to separate the contributions of the sigma and pi bands to the total conductance of our point contacts. By using this technique, we were able to obtain the temperature dependency of each gap independent of the other. The consequent, strong reduction of the error on the value of the gap amplitude as function of temperature allows a stricter test of the predictions of the two-band model for MgB_2.

4 pages, 5 eps figures. References added, Fig.1 changed, some text added

References in corpus (15)

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• Two Gap State Density in MgB${}_2$: A True Bulk Property or A Proximity Effect?
• Two-Band Superconductivity in MgB2
• Multiband model for tunneling in MgB2 junctions
• Temperature and field dependence of the anisotropy of MgB2
• Thermal conductivity of single crystalline MgB_2
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• The structure of the superconducting gap in MgB2 from point-contact spectroscopy
• Superconducting energy gap distribution in c-axis oriented MgB${}_2$ thin film from point contact study
• Temperature and Field Dependence of the Energy Gap of MgB2/Pb planar junction

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