Evidence for Two Superconducting Energy Gaps in MgB2 by Point-Contact Spectroscopy

P. Szabó; P. Samuely; J. Kačmarčík; T. Klein; J. Marcus; D. Fruchart; S. Miraglia; C. Marcenat; A. G. M. Jansen

doi:10.1103/PhysRevLett.87.137005

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Evidence for Two Superconducting Energy Gaps in MgB2 by Point-Contact Spectroscopy

P. Szabó, P. Samuely, J. Kačmarčík, T. Klein, J. Marcus, D. Fruchart, S. Miraglia, C. Marcenat, A. G. M. Jansen

DOI 10.1103/PhysRevLett.87.137005 · Physical Review Letters

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Abstract

Experimental support is found for the multiband model of the superconductivity in the recently discovered system MgB2 with the transition temperature Tc=39K. By means of Andreev reflection, evidence is obtained for two distinct superconducting energy gaps. The sizes of the two gaps ( ΔS=2.8meV and ΔL=7meV) are, respectively, smaller and larger than the expected weak coupling value. Because of the temperature smearing of the spectra the two gaps are hardly distinguishable at elevated temperatures, but when a magnetic field is applied the presence of two gaps can be demonstrated close to the bulk Tc in the raw data.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	39	Pressure not reported	unknown
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	39.3	Pressure not reported	onset
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	39.3	Pressure not reported	onset