ITINERANT ELECTRON METAMAGNETISM AND A LARGE DECREASE IN THE ELECTRONIC SPECIFIC-HEAT COEFFICIENT OF LAVES-PHASE COMPOUNDS LU(CO1-XGAX)2

High-field magnetization and low-temperature specific heat of the nearly ferromagnetic compounds Lu(Co1-xGax)2 have been investigated. A sharp metamagnetic transition has been observed in these compounds. The critical field Hc decreases with increasing x and becomes lower than 1 T at x = 0.12. However, no spontaneous magnetization is confirmed even above x = 0.15. With increasing x, the electronic specific heat coefficient gamma increases and reaches 36 mJ K-2 mol-1 for x = 0.12 in 0 T, being 1.5 times as large as that of LuCo2. Such a mass enhancement is discussed in terms of the spin fluctuation. The gamma value of the ferromagnetic state for the specimen with x = 0.12 in a magnetic field of 14.6 T is reduced about 50% compared with that of the paramagnetic state in zero field. This means that the metamagnetic transition results in a drastic reduction of the spin fluctuation in the compound.