The magnetocaloric properties of a thin spacer of gadolinium (Gd) between layers of "strong" ferromagnets (relatively high Curie temperatures) are studied experimentally. It is found that, at room temperatures, the magnetocaloric efficiency Delta S/Delta H (Delta S is the isothermal magnetic entropy change and Delta H is the range of applied magnetic fields) of Gd spacer of thickness of 3 nm is up to two orders in magnitude higher than this value in an individual thicker (30 nm) Gd layer. This opens up opportunities for using the magnetocaloric effect in micro(nano)electronics and biomedicine using relatively weak magnetic fields H<1 kOe. The observed increase in the magnetocaloric efficiency is explained by the influence of direct exchange coupling between Gd spacer and its surroundings, which changes the distribution of magnetization in the spacer and, ultimately, its magnetocaloric potential. Keywords: magnetocaloric effect, magnetic heterostructures, exchange coupling at interfaces, Curie temperature.

We experimentally studied the generation of optical second harmonic (SH) and magneto-optical effects at the SH frequency in thin films consisting of ferromagnetic and antiferromagnetic materials, including exchange-bonded layers, one of which is pinned with an antiferromagnetic layer. As expected, the loops of the linear magneto-optical Kerr effect are shifted relative to the zero magnetic field value, which reflects the presence of a pronounced exchange interaction in such structures. It is shown that in the case of the nonlinear Kerr magneto-optical effect this effect is also present, but it is significantly smaller than in the nonlinear case, and leads to the observation of only one hysteresis loop instead of two. The studied dependence of the magneto-optical response at the TH frequency on the probing laser radiation power demonstrates that its growth leads to a decrease in the magnetic hysteresis loop shift of the TH. Keywords: magnetization-induced SHG, ferromagnet/antiferromagnet interface, pinned structure, thin films