The magnetic behavior of (Y1-xTbx)(3)Co11B4 intermetallic compounds

The R3Co11B4 compounds belong to the Rn+1Co3n+5B2n intermetallic systems. T he R3Co11B4 borides crystallize in a hexagonal structure of Ce3Co11B4 type having the space group P6/mmm. The composition dependencies of the lattice parameters in (Y1-xTbx)(3)Co11B4 compounds are linear and different for a a nd c parameters. The magnetic properties of (Y1-xTbx)(3)Co11B4 compounds we re investigated in the temperature range 4.2-950 K and external fields up t o 10 T. The Y3Co11B4 compound is ferromagnetically ordered. For the compoun ds with x > 0, a ferrimagnetic ordering is evidenced. The Curie temperature s increase when yttrium is substituted by terbium, as a consequence of the increase of the exchange interactions in the system. The magnetic behavior of cobalt in the above system is analyzed.