Magnetic and magneto-optical studies in Co-Tb/Pt multilayers

We have prepared Co86Tb14/Pt multilayers by r.f. sputtering and studied their magnetic and magneto-optical properties. As the Co-Tb layer thickness (t(CoTb)) decreases bellow 200 Angstrom the saturation magnetization increases, the rectangularity of the M-H loops and the coercivity decrease. The effective anisotropy K-eff of the multilayers was determined by a torque magnetometer. The product K-eff x t(CoTb) shows a linear dependence with t(CoTb) as normally found for the superlattices yielding the bulk and surface anisotropies of 1 x 10(6) erg cm(-3) and - 0.2 erg cm(-2), respectively. These results are explained in terms of an interfacial Co-Pt layer. The polar Kerr rotation for the multilayers is found independent of layer thickness and is equal to 11.5 min, which is higher than the single thick layer. (C) 1998 Elsevier Science Ltd. All rights reserved.