Physico-Chemical nanomaterials science

Two-band nature of superconductivity in molybdenum-rhenium alloys
Shapovalov A.P.1, Boliasova O.O.2, Dmitrenko V.Yu.2, Tarenkov V.Yu.2
1 G. V. Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky Blvd., UA-03142 Kyiv, Ukraine.
2 Donetsk Institute for Physics and Engineering Named after O. O. Galkin, NAS of Ukraine, 46 Nauky Ave., UA-03028 Kyiv, Ukraine.
E-mail: dmitrenko_v@ukr.net

The class of multiband superconductors (SCs) includes not only the ‘classical’ two-band MgB2, but also such as high-temperature SCs. The discovery of another two-band SC, Mo1-xRex, with a conventional electron-phonon pairing mechanism allows a more detailed study of the nature of multi-band superconductivity, the unique dynamic characteristics of which can manifest themselves in various functional devices. 
Characteristics of Mo1-xRex alloys [1] indicating two-band nature of superconductivity were obtained from the measurements the electronic heat capacity and the magnetic field penetration depth. The Andreev spectroscopy gives an unambiguous result in terms of a microscopic nature of the investigated superconducting state. In this report, a series of experiments were carried out to study the conductivity of Mo0.52Re0.48-Ag (S-N) contacts. Point contacts of the Andreev type are prepared by the sliding electrode method of a silver needle on a MoRe film, or a MoRe needle in contact with a silver electrode. From the obtained Andreev spectra for both film and bulk samples of the MoRe alloy, the two energy gaps have been restored: a large MoRe =2.45 mV and a small L 0.34 mV. A similar conclusion was obtained from the experiments on temperature dependence of the heat capacity of this SC [1]. The ratio 20/kTc = 4.2 ± 0,1 indicates a strongly coupled nature of superconductivity in the bulk and film of Mo0.52Re0.48. 

1.	Sundar S., Chandra L.S. Sharath, Chattopadhyay M.K., Roy S.B. Evidence of multiband superconductivity in the β-phase Mo1-xRex alloys // J. Phys. Condens. Matter. – 2015. – 27. P. 045701.