Neutron diffraction, magnetic and superconducting measurements on vanadium-manganese-gallium alloys

Eleven alloys from the binary and ternary range (VMn)₂Ga₅ have been investigated using neutron powder diffraction methods supported by measurements of magnetic susceptibility and superconducting transition temperatures. A magnetic structure is present in alloys in the composition range around (Mn_0.2V_0.8)₂Ga₅ to Mn₂Ga₅. The magnetic moment found in the alloy Mn₂Ga₅ increases on the addition of vanadium to a maximum around the composition (Mn_0.2V_0.2)₂Ga₅. It then decreases and disappears around the composition (Mn_0.2V_0.8)₂Ga₅. Possible changes in the magnetic structure are suggested in order to account for this. There is some evidence of weak superconductivity in the alloy V₂Ga₅. This disappears on the addition of manganese.