The magnetic properties of CeCoMn, Ce₃Co₃Mn₄ and Ce₃Co₆Mn alloys have been investigated by magnetization and susceptibility measurements in the temperature range (5-300) K and magnetic field up to 12 T. X-ray powder diffraction measurements showed that all three alloys are isostructural and crystallize in the cubic MgCu₂ structure type. Both Ce and Co atoms are non-magnetic in all alloys like in the isostructural compound CeCo₂. Magnetic behavior of the investigated alloys is mostly due to the Mn moments and depends essentially on the Mn-Mn distances. The interaction between the Mn moments is antiferromagnetic in CeCoMn and Ce₃Co₃Mn₄ but a paramagnetic behavior for Ce₃Co₆Mn was evidenced in the studied temperature range.
Study of pressure effects on magnetic and transport properties of CeCo_{12}B_6 and CeFe_2Co_{10}B_6 was performed in temperature range 5-300 K at pressures up to 9 kbar. The significant decrease in the Curie temperature T_C as a consequence of Fe substitution from (135±1) K to (85±1) K is not accompanied by the changes of saturation magnetization. The decrease in T_C with pressure is the same for both samples -ΔT_C/Δp ≈ -0.5 K/kbar. The relative decrease in saturation magnetization with pressure is about 0.3%/kbar for both samples. Pressure induced resistivity changes were below 1%. The relatively low pressure effect on both the T_C and magnetization can be attributed to the hybridization as a consequence of small distances between the Co and B atoms.
Study of resistivity and specific heat on CeCo_{12}B_6 compound was performed in a temperature range 2.5-300 K. The specific heat exhibits pronounced λ-type anomaly in the vicinity of the Curie temperature T_C. Using the Debye-Einstein model the following parameters were obtained: the Debye temperature θ_D = 185 K, coefficient of the electron specific heat γ_{el} = 115 mJ/mol K. The parabolic temperature dependence of resistivity ρ(T) = ρ_0 + A_ρT^2 was observed below T_C in agreement with ferromagnetic state. Comparison of dρ/dT(T) with C_M(T) allows to confirm their similar character, accordingly to theory of critical behavior.
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