Evidence for spin fluctuations in vanadium from a tunneling study of Fermi-liquid effects

The Fermi-liquid parameter $G_0$ is found to be close to zero in vanadium, providing new experimental evidence for the importance of spin fluctuations in this material. Al/${\mathrm{Al}}_2$ ${\mathrm{O}}_3$/V and V/${\mathrm{Al}}_2$ ${\mathrm{O}}_3$/Fe tunnel junctions were used to observe the renormalization caused by Fermi-liquid interactions of the spin splitting of the vanadium’s superconducting density of states in a magnetic field. This was done by fitting the theory of Rainer to the measured dynamic tunneling conductance. Excellent agreement was found with this theory, and the results were consistent with critical field measurements made on the same vanadium films. The spin-orbit scattering rate $b_{\mathrm{so}}$ was determined to be 0.07±0.03.