Electronic structure, magnetic and Fermi surface calculations of heavy-fermions superconductors compounds based on Nb3Sn
Journal
International Journal of Nanoelectronics and Materials (IJNeaM)
ISSN
1985-5761
Date Issued
2008-01
Author(s)
Badis Bendjemil
University of Annaba
Abstract
We report a theoretical investigation of the electronic structures and Fermi surface of the
heavy-fermion superconductors Nb3Sn. The electronic structures are investigated ab-initio on
the basis of full-potential local orbital minimum-basis band- structure calculations (FPLO),
adopting both the scalar- and fully relativistic formulations within the framework of the local
spin-density approximation (LSDA). The possibility of a partial 4d localization occurring for
compounds is discussed. The electronic structures of the Nb3Sn compounds are computed to
be rather similar to the literature. Our total-energy calculations predict paramagnetic and
ferromagnetic order to be favorable for Nb3Sn materials, which is, however, observed
experimentally. Also, the calculated magnetic moment is 0.35 μB. Furthermore, the theoretical
Fermi surfaces topology and the possible origins of the superconductivity are discussed. The
Bardeen, Cooper and Schreiffer (BCS) energy gap and the Ginzburg-Landau (GL) parameter
K for these compounds have been calculated from the Fermi velocity. We found strong
indication suggesting the existence of a second superconducting (SC) gap in Nb3Sn. In
addition, the average superconductivity-gap at zero temperature is calculated for this
compound. The knowledge of energy gap value gives important information on the coupling
scenarios. Our results provide an explanation between the electronic structures, the Fermi
surface (FS) topology and two-band model of the superconductivity.