Determination of the elementary jump of Co in CoGa by quasielastic neutron scattering

Quasielastic neutron scattering at the backscattering spectrometer IN16 at the ILL has been used to determine the elementary jump vector of diffusing Co atoms in the B2 phase of CoGa. Measurements have been performed on Co single crystals with 54 at. % Co and 64 at. % Co. For both compositions a maximum of the quasielastic broadening has been observed near a reciprocal lattice point corresponding to a B2 superlattice reflection. This gives unambiguous evidence of Co diffusion via nearest neighbor jumps. From the residence times on the antistructure sites high defect concentrations are deduced. The correlation of Co diffusion has been found to be surprisingly weak. A diffusion mechanism is suggested which takes advantage of the high degree of disorder and, therefore, cannot be described in terms of defined cycles.