| Popis: |
The low-temperature properties of single-crystal CeCoGe were investigated by specific heat C(T,H), magnetoresistivity ρ(T,H), and differential susceptibility measurements χ(T,H). The zero-field low-temperature specific heat evolves as C = γT+βT(3) = 42T+23.5T(3) mJ mol(-1) K(-1). On comparing its γ = 42 mJ mol(-1) K(-1) with that of LaCoGe (12 mJ mol(-1) K(-2)) it is inferred that both 3d (Co) and 4f (Ce) orbitals contribute to the density of states at the Fermi level. Assuming that its phonic contribution to the specific heat is similar to LaCoGe (β = 0.5 mJ mol(-1) K(-4)), then the extra cubic term in the specific heat (23T(3) mJ mol(-1) K(-1)) must be due to magnon excitation within the antiferromagnetically ordered state, TT(N). On the other hand, the thermal evolution of the resistivity is found to be dominated by the following scattering processes: magnon scattering operating within the ordered state at TT(N) leading to a T(4) resistive contribution and a spin fluctuation process associated with the Co subsystem giving rise to both a quadratic resistive term below 15 K and a saturated resistive term at higher temperatures. The isothermal magnetoresistivity below T(N), ρ(TT(N),H), manifests a peak which is centered at the same critical field that appears in the magnetization isotherms. This peak, together with the peak observed at a temperature 0.7 K below T(N), is attributed to a spin rearrangement of the AFM structure of the Ce sublattice. |
