Here we report transverse bias initial susceptibility (TBIS) measurements on amorphous GdCo2/YCo2/GdCo2 (Gd/Y/Gd) and YCo2/GdCo2/YCo2 (Y/Gd/Y) sandwiches (1000 angstrom/1000 angstrom/1000 angstrom) in order to study the interlayer exchange coupling. TBIS was measured by using the magneto-optic Kerr effect. The sandwiched layer of the Gd/Y/Gd and Y/Gd/Y systems reverses its magnetization at an applied magnetic field determined by the compensation between the gain in Zeeman energy and the loss in wall energy. It is observed that the magnetization reversal of the inner layer cannot occur by a coherent-rotation process.