Magnetization, Flux Flow Resistance and Hall Effect in Superconducting Vanadium

Abstract

The magnetization, the flux flow resistivity and the Hall voltage have been measured for three vanadium specimens with different purities. The parameters pertinent to the magnetic properties of type II superconductors near the upper critical field H c 2 –the Ginzburg-Landau-Maki parameters κ 1 and κ 2 , and the Helfand-Werthamer parameters h * and (d h /d t )–were obtained from the data. It was found that the values of κ 1 , κ 2 and h * at 0°K increased with increasing purity and the magnitude of the increase of them was larger than the value expected from the microscopic theory. This discrepancy between experiment and theory seems to correspond to the effect of the non-spherical Fermi surface suggested by Hohenberg and Werthamer. Resistivity measurements showed that with increasing purity, the behavior of the slope of the flow resistivity near H c 2 changed from that of the dirty material predicted by Caroli-Maki to that of intermediate material. This result is different from the Kim's empirical relation. The Hall angle in the mixed state is found to be strongly dependent on the electron mean free path.