Magnetoresistance of LuMn6Ge6-xGax compounds (x=0.2, 0.4, 0.6)

The magnetisation and the magnetoresistance of the LuMn6Ge6-xGax compounds (x=0.2, 0.4, 0.6) at 10 and 295 K in applied magnetic fields up to 9 T is presented. The partial substitution of Ga for Ge leads to a large and significant increase of the c/a ratio with different changes in Mn-Mn distances. Rather large negative values of magnetoresistance are observed for the x=0.4 and 0.6 phases and are related to the presence of metamagnetic transitions