Probing Cluster Dynamics in Quantum Griffiths Phase in Ni-Cr

We propose to use muSR to study the unconventional excitations of the d-metal alloy Ni-Cr close to a ferromagnetic quantum phase transition (QPT). muSR is a uniquely sensitive probe of small moments and partial ordering, giving us access to the rare regions that determine the characteristic features of the quantum Griffiths phase, a special region close to a disordered QPT. Our previous muSR study of Ni-V resolved the magnetic fluctuations from the static order but only gave limited information on the dynamics because of the V nuclear moment. Measuring Ni-Cr removes this nuclear contribution to the muon signal in a system that is otherwise very similar, giving us access to hitherto unexplored dynamically behaviour.