High Pressure Effect on the Superconductivity in VN

We revisited the superconductivity in a vanadium-based superconductor VNx with a special focus on its high-pressure effect. We found that the electronic specific heat at low temperature follows a single gap BCS-type function, indicating the s-wave symmetry of superconducting gap. We also revealed that the superconducting transition temperature (T-c) enhances as the pressure increases up to 8 GPa, giving a positive differential pressure coefficient of 0.09K=GPa. The enhancement of T-c was discussed in terms of the suppressed spin fluctuations, and the phonon softening.