We measured the electrical resistivity, specific heat and de Haas-van
Alphen (dHvA) oscillation of an antiferromagnetic compound GdCu2. The
magnetic entropy, which was obtained from the specific heat, reaches R
ln8 above 47 K, which is close to the Neel temperature of 40 K. The dH
vA branches both in the antiferromagnetic state and the field-induced
ferromagnetic state are highly different from those of a non-magnetic
reference compound YCu2 or PrCu2. The Fermi surface in GdCu2 is most l
ikely altered by the magnetic state.