Unconventional superconductivity in noncentrosymmetric Mo$_{3}$Al$_{2}$C

We have presented experimental results of resistivity, magnetic susceptibility, penetration depth and specific heat measurements for a polycrystalline sample of the noncentrosymmetric superconductor Mo$_{3}$Al$_{2}$C. All measurements confirm a bulk superconducting transition at 9 K in this compound. A high value of the upper critical field $H_{c2}$(0) suggests that pair breaking due to the Zeeman effect in Mo$_{3}$Al$_{2}$C is small. The specific heat jump $\Delta $\textit{C/$\gamma $T}$_{c}$ at \textit{Tc }was found to be 1.95, higher than the BCS value of 1.43 for a weakly coupled superconductor, suggesting that Mo$_{3}$Al$_{2}$C may be strongly coupled. In addition, evidence for unconventional superconductivity is clearly apparent in the electronic specific heat $C_{es}$ and the penetration depth $\lambda _{s}$ in the superconducting state, indicating an anomalous pairing mechanism and a possible nodal-gap structure in Mo$_{3}$Al$_{2}$C.