Magnetic field H dependence of the electronic specific heat coefficient y was measured in various NbSe2 crystals in the vortex states. With increasing residual resistivity ratio, γ(H) changed from conventional γ ∝ H behavior to the strongly sublinear function of H. The sublinear H dependence of γ is similar to that of nodal superconductors, while NbSe2 is a nodeless superconductor. From measurements on the sample containing columnar defects, we found that the γ anomaly is brought by quasi-particle states outside of the vortex cores. This result suggests that excess quasi-particle states are generated by Doppler energy shift caused by supercurrent around vortices.
- Electronic specific heat coefficient
- Vortex state
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering