MAGNETORESISTANCE MEASUREMENTS ON DILUTE (PDNI)MN ALLOYS

The magnetoresistance of several (Pd//0//. //9//8//5Ni//0//. //0//1//5)-based alloys containing between 0. 5 and 2. 5 at. % Mn has been measured as a function of field up to 85 kOe at 1. 5 and 4. 2 K and as a function of temperature between 1. 5 and 4. 2 K in a fixed field of 70 kOe. The first type of measurement provides qualitative evidence that as a result of competing interactions between Mn impurities, the ground state of these systems is frustrated, with the degree of frustration increasing with Mn concentration. The second type yields information on the collective excitations out of this ground state and how they may be modified by frustration effects.