Thermopower of vanadium group of metals: A Revisit

We have reinvestigated the thermopower of uncontaminated good quality samples of V, Nb and Ta in the temperature range 6–300K. The completely new features of significantly smaller magnitude, (negative) sign, phonon drag dip and influence of superconductivity of the thermopower data were studied quantitatively using the theoretical fittings. These give the Fermi energy of 10.94eV, 5.08eV and 1.86eV respectively. These are significantly smaller than those estimated from the free electron model, indicating strong and predominating s-d scattering over s-s scattering among the electrons, phonons and defects in the jungle-gym type Fermi surfaces of these metals. The poor fitting of the phonon-drag peaks leads to the much higher Debye temperatures than those obtained from other methods such as specific heat. Their details are discussed.