1970/01/15 by L. F. Mattheiss · 1 voice · 3 citations
Physics and Astronomy · #Advanced Chemical Physics Studies #Physics of Superconductivity and Magnetism #Superconductivity in MgB2 and Alloys
paper · doi:10.1103/physrevb.1.373
openalex publication_date 1970/01/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/04/02
The band structures and Fermi surfaces of niobium and tantalum have been calculated via the augmented-plane-wave (APW) method. Relativistic effects have been included in the tantalum but not the niobium calculation. The resulting niobium and tantalum Fermi surfaces are similar to a Fermi-surface model for the vanadium-group transition metals that was proposed previously by the author. This model contains closed hole pockets centered at the symmetry points \ensuremathΓ and N of the bcc Brillouin zone plus a multiply connected hole sheet which extends from \ensuremathΓ to H along 〈100〉 directions. Areas and cyclotron masses of closed extremal orbits on the niobium and tantalum Fermi surfaces have been calculated as a function of magnetic field direction in the 100 and 110 planes. The calculated areas are in quantitative agreement with recent experimental results. The maximum discrepancies are 18 and 10% for niobium and tantalum, respectively. The effect of niobium Fermi-surface anisotropy on the temperature dependence of the upper critical field has been evaluated in terms of the Hohenberg-Werthamer theory. The results of this calculation overestimate the experimentally observed effect by a factor of about 2.5.