Structure and paramagnetism in weakly correlated Y₈Co ₅

We report the basic physical properties of monoclinic Y₈Co ₅ determined by means of magnetic susceptibility, electrical resistivity, and specific heat measurements. The crystal structure of Y ₈Co₅ is monoclinic (P2₁/c) with lattice parameters a = 7.0582(6) Å, b = 7.2894(6) Å, c = 24.2234(19) Å, and β = 102.112(6)° as refined by using synchrotron powder x-ray diffraction data. The compound shows temperature independent paramagnetism with χ0 = 2.1 × 10^-3 emu mol^-1 and Sommerfeld parameter γ = 63 mJ mol^-1 K^-2. The calculated Wilson ratio for Y₈Co₅, R_W = 1.4, is close to that expected for a free electron gas R_W = 1. Low temperature resistivity under high pressure does not reveal superconductivity in this compound down to 1.2 K, up to hydrostatic pressures of 5.56 GPa. Band structure calculations (full-potential linearized augmented plane wave, FP-LAPW) derive the Stoner exchange interaction parameter S = 0.24, excluding magnetic behavior for Y ₈Co₅.