Temperature Dependence of Superconducting Gaps in Mg(Al)B2 System Investigated by SnS-Andreev Spectroscopy

Abstract

Detailed temperature dependence of both superconducting gaps was obtained directly by means of SnS-Andreev spectroscopy. The Δσ,π(T) -curves were shown to be deviated from standard BCS-like behavior, due to k-space proximity effect between σ- and π- condensates, which could give a key to experimental determination of interband electron-phonon coupling constants. For the first time, an excellent qualitative agreement with theoretical predictions of Nicol and Carbotte, and Moskalenko and Suhl was shown. dI(V)/dV-spectra of SnS-Andreev contacts based on MgB2 samples (with defects of crystal structure), and Mg(Al)B2 polycrystalline samples (with the local critical temperatures Tc variation 10 K < Tc < 37 K) were studied by means of the "break-junction" technique within the temperature range 4.2 K < T < Tc.

13 pages; 3 figures; typos are corrected in v3; submitted to Solid State Communications

References in corpus (6)

• Band filling and interband scattering effects in MgB${}_2$: C vs Al doping
• Al substitution in MgB2 crystals: influence on superconducting and structural properties
• Influence of Al doping on the critical fields and gap values in magnesium diboride single crystals
• Point-contact spectroscopy in neutron-irradiated Mg^{11}B_2
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• Local Tunneling Study of Three-Dimensional Order Parameter in the $\pi$-band of Al-doped MgB${}_2$ Single Crystals

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