De-Haas-van Alphen effect study of electronic structures of niobium-based molybdenum alloys

The electronic structures of dilute niobium-based molybdenum alloys have been studied by using the de Haas-van Alphen effect. The rate of increase of the Dingle temperature ( Delta T_D*) on alloying is found to be fairly small compared with that of noble-metal alloys and to be anisotropic over the Fermi surfaces that is, 3K (at.% Mo)^-1 for nu oscillations arising from the ellipsoids, and 7K (at.% Mo)^-1 for alpha and eta oscillations arising from the jungle gym. The change in frequency of the nu ₃₄₅₆ oscillation is about ²/₃ that predicted by the rigid band model. Applying the partial-wave analysis to these experimental facts, the following results are obtained. (i) The d wave phase shift dominates over s, p and f wave phase shifts in this alloy system and the anisotropy in Delta T_D* results from the anisotropy in the amount of d component of the wavefunction over the Fermi surfaces. (ii) The non-rigid band-like behaviour of the nu ₃₄₅₆ oscillation arises from the same origin as Delta T_D*. (iii) The significantly small Delta T _D* found in the present experiment is related to a small electron group velocity on the Fermi surfaces in niobium.