Systematic study of the two band/two gap superconductivity in carbon-substituted MgB2 by point-contact spectroscopy

Point-contact measurements on the carbon-substituted Mg(B$_{1-x}$C$_x$)$_2$ filament/powder samples directly reveal a retention of the two superconducting energy gaps in the whole doping range from $x = 0$ to $x \approx 0.1$. The large gap on the $\sigma$-band is decreased in an essentially linear fashion with increasing the carbon concentrations. The changes in the the small gap $\Delta_{\pi}$ up to 3.8 % C are proportionally smaller and are more difficult to detect but for the heavily doped sample with $x \approx 0.1$ and $T_c = 22$ K both gaps are still present, and significantly reduced, consistent with a strong essentially linear, reduction of each gap with the transition temperature.Comment: 5 eps figure

Systematic study of two-band/two-gap superconductivity in carbon-substituted MgB2 by point-contact spectroscopy

Point-contact measurements on the carbon-substituted Mg(B1-xCx)(2) filament/powder samples directly reveal a retention of the two superconducting energy gaps in the whole doping range from x=0 to xapproximate to0.1. The large gap on the sigma-band is decreased in an essentially linear fashion with increasing the carbon concentrations. The changes in the small gap Delta(pi) up to 3.8% C are proportionally smaller and are more difficult to detect but for the heavily doped sample with xapproximate to0.1 and T-c=22 K both gaps are still present, and significantly reduced, consistent with a strong essentially linear, reduction of each gap with the transition temperature.This article is published as Hoľanová, Z., P. Szabó, P. Samuely, R. H. T. Wilke, S. L. Bud’ko, and P. C. Canfield. "Systematic study of two-band/two-gap superconductivity in carbon-substituted MgB 2 by point-contact spectroscopy." Physical Review B 70, no. 6 (2004): 064520. DOI: 10.1103/PhysRevB.70.064520. Copyright 2004 American Physical Society. Posted with permission

Two-band/two-gap superconductivity in carbon-substituted MgB2 evidenced by point-contact spectroscopy

The Andreev reflection measurements of the superconducting energy gap in the carbon-substituted MgB2 are presented. Despite the strong suppression of the transition temperature by 17 K in comparison with the pure MgB2, the same reduced value of the small superconducting energy gap with 2Delta/kT(c)approximate to1.7 has been systematically observed. This indicates that the two-band/two-gap superconductivity is still preserved here.This article is published as Samuely, P., Z. Hoľanová, P. Szabó, J. Kačmarčík, R. A. Ribeiro, S. L. Bud’ko, and P. C. Canfield. "Two-band/two-gap superconductivity in carbon-substituted MgB 2 evidenced by point-contact spectroscopy." Physical Review B 68, no. 2 (2003): 020505. DOI: 10.1103/PhysRevB.68.020505. Copyright 2003 American Physical Society. Posted with permission

Two-band/two-gap superconductivity in carbon-substituted MgB2 evidenced by point-contact spectroscopy

The Andreev reflection measurements of the superconducting energy gap in the carbon-substituted MgB2 are presented. Despite the strong suppression of the transition temperature by 17 K in comparison with the pure MgB2, the same reduced value of the small superconducting energy gap with 2Delta/kT(c)approximate to1.7 has been systematically observed. This indicates that the two-band/two-gap superconductivity is still preserved here.This article is published as Samuely, P., Z. Hoľanová, P. Szabó, J. Kačmarčík, R. A. Ribeiro, S. L. Bud’ko, and P. C. Canfield. "Two-band/two-gap superconductivity in carbon-substituted MgB 2 evidenced by point-contact spectroscopy." Physical Review B 68, no. 2 (2003): 020505. DOI: 10.1103/PhysRevB.68.020505. Copyright 2003 American Physical Society. Posted with permission