Antiferromagnetic ordering in the ternary rare earth cobalt borides RCo4B4 (R=Ce, Gd, Tb, Dy, Ho, Er, Tm, Lu)

Antiferromagnetic Neel temperatures (TN) are reported for magnetic rare earth cobalt compounds RCo4B4 (R=Gd, Tb, Dy, Ho, Er, Tm) which crystallize with the primitive tetragonal CeCo4B4-type structure. The maximum TN of 3.68 K was observed in TbCo4B4, while TmCo4B4 has the lowest ordering temperature of 0.17 K. No magnetic transition was observed for CeCo4B4 and LuCo4B4 down to 60 mK. The complex evolution from antiferromagnetic order in HoCo4B4 (TN=1.91 K) to ferromagentic order in HoRh4B4 (TC=6.56 K) of the pseudoternary system Ho(Rh1-xCox)4B4 is briefly discussed.