The superconducting properties of the spin fluctuation-superconductor ${\mathrm{Mo}}_3{\mathrm{Sb}}_7$ have been investigated by specific heat measurements down to $0.5\mathrm{K}$ and under magnetic fields of up to $2\mathrm{T}$. The obtained temperature and magnetic field dependences of the electronic specific heat strongly suggest a conventional $s$-wave pairing, while possible $(s+g)$-wave pairing symmetry has been proposed earlier. In addition, the temperature dependence of the upper critical field $H_{c2}$ is fully consistent with the Werthamer–Helfand–Hohenberg theory predicting its behavior for a conventional phonon-mediated type II superconductor.

• Received 20 September 2007

DOI:https://doi.org/10.1103/PhysRevB.77.092509