Heat capacity measurements of itinerant electron magnetism in Y3Ni13−xCOxB2 system

The heat capacity of the Y₃Ni_13−xCo_xB₂ series has been measured from 300 mK to RT. The magnetic ordering phase transitions have been characterized as second-order type and the T_c's determined. The electronic contribution to the low-temperature heat capacity for x=0 yields an electronic constant γ=54 mJ mol K², which is higher than those of YNi₅ and YNi₄B, proving experimentally that its density of states at the Fermi surface is larger than in those other compounds. The substitution of Ni by Co increases γ linearly. Electronic band calculations could explain these features.