Finite Temperature Study of the Itinerant Metamagnetic Transition in Y(Co1-xAlx)2

Isothermal magnetizations of itinerant metamagnet Y(Co 1- x Al x ) 2 , x =0.08∼0.11, were measured in static fields up to 23 T at various temperatures 3.6∼30 K. Temperature variation of the magnetization M is found to change dramatically around the metamagnetic field H c , from ∂ M /∂ T >0 ( H < H c ) to ∂ M /∂ T <0 ( H ≥ H c ). Using the thermodynamic relations, the field dependence of the electronic specific heat coefficient γ is estimated. The γ 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 γ 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 γ continues to higher fields. These results suggest that the spin fluctuation behavior of this system is strongly affected by the metamagnetic transition.