Use of magnetization density fluctuation spectra to estimate the electrical resistivity in YCo2

Key physical properties of the non-magnetic RCo2 compounds (R = Sc, Y and Lu) suggest that their behaviour is dominated by spin fluctuations. For example, the enhanced linear term in the heat capacity and the T2 increase of the resistivity at low temperatures followed by a pronounced saturation of ρ against T at ambient temperatures have been taken as evidence for this mechanism. We report the measurement of the dynamical spin fluctuation spectrum in polycrystalline YCo2 (ScCo2) samples by a combination of time-of-flight neutron scattering with high energy resolution on the IN5 spectrometer of the Institut Laue-Langevin (ILL) Grenoble with results obtained from the polarized neutron diffractometer D7 (ILL). The low frequency properties of the generalized magnetic susceptibility have been modelled by a single imaginary pole: Im[χ(q,ω)]=ωzχ(q)Γ(q)[ω2Γ(q)2]-1 with the static wavevector dependent susceptibility approximated by χ(q)-1=χ-10+cq2. From the resistivity data we have extracted the spin scattering component and show that it is consistent, using a simple model based on the Boltzmann formalism, with Im[χ(q,ω)] as measured by neutron scattering. In this analysis, the stiffness constant, c, which is found to be temperature dependent, appears critical in modelling the saturation of ρ on approaching ambient temperatures. (author)