Search

The superconducting properties of a series of ZrNi2-xTMxGa (TM = Cu, Co) and ZrNi2AlxGa1-x Heusler compounds have been explored by x-ray diffraction, scanning electron microscopy, electrical resistivity, dc magnetization and ac susceptibility measurements. In common, all samples exhibited the cubic L21 Heusler structure at room temperature. For x = 0.25, the ZrNi2-xCuxGa compounds demonstrated superconductivity and the superconducting transition temperature, TC, decreased with increasing Cu concentration. The dc magnetization data suggested the type-II superconductivity for all the Cu-doped compounds. Unlike ZrNi2-xCuxGa, up to the lowest measuring temperature of 1.75 K, no superconductivity was observed in any of the ZrNi2-xCoxGa compounds. All the Al-doped compounds also showed type-II superconductivity with a decrease in Tc. In addition, the ZrNi2AlxGa1-x compounds showed a new phase transition a few kelvins above superconducting transition. The experimental results are presented and discussed in detail.