Hall coefficient of vanadium carbide as a function of temperature and carbon concentration

Abstract

The Hall coefficient R of single crystals of vanadium carbide (VC_x) with carbon‐to‐metal ratios (x) ranging from 0.83 to 0.88 were measured between 4.2 and 300 K. The behavior of R versus T is found to depend critically on x, as well as the type of ordered structure (V₈C₇ or V₆C₅) present. The data are interpreted in terms of a two‐band model which allows for the effects of anisotropic scattering. It is proposed that a minimum in R (x) at x = 0.875 (V₈C₇) results from an increase in relaxation time, rather than a change in band structure for the ordered compound. The two‐band analysis is consistent with the specific heat data of Lowndes, Finegold, and Lye which show a maximum in the density near the ordered compound V₆C₅.