Superconductivity of Ni₂NbX (X=Al, Ga and Sn)

Superconductivity are reported for three ternary compounds with Heusler type structure Ni 2 NbX (X=Al, Ga, Sn). Critical temperatures up to 2.9 K are observed from the electrical resistivity and the specific heat measurement. Electron-phonon coupling constants calculated using McMillan's formula indicate that these compounds are intermediate-coupled superconductors.