FINITE-TEMPERATURE STUDY OF THE ITINERANT METAMAGNETIC TRANSITION IN Y(CO1-XALX)(2)

Isothermal magnetizations of itinerant metamagnet Y(Co1-xAlx)(2), x=0.08 similar to 0.11, were measured in static fields up to 23 T at various temperatures 3.6 similar to 30 K. Temperature variation of the magnetization M is found to change dramatically around the metamagnetic field H-c, from partial derivative M/partial derivative T>0 (H<H-c) to partial derivative M/partial derivative T<0 (H greater than or equal to H-c). Using the thermodynamic relations, the field dependence of the electronic specific heat coefficient gamma is estimated. The gamma value is enhanced as H approaches H-c from lower field. However, the enhancement is weak and is not divergent, consistent with the first-order transition at H-c. There is a sudden decrease of gamma at around H-c, indicating a significant reduction of the density of state or a suppression of the spin fluctuations. For H>H-c, gradual decrease of gamma continues to higher fields. These results suggest that the spin fluctuation behavior of this system is strongly affected by the metamagnetic transition.