We have studied the magnetic and magnetotransport properties of Fe/Cu multilayers prepared by sputtering. We find oscillations of the interlayer coupling as a function of the Cu thickness with the same long period as in Co/Cu multilayers (around 12.5 Å). The most striking result is that the oscillations in Fe/Cu and Co/Cu have almost exactly opposite phases. A large magnetoresistance of the spin-valve type is observed in the half periods with antiferromagnetic interlayer exchange. However, the magnetoresistance in Fe/Cu is definitely smaller than in Co/Cu.

We investigate experimentally and theoretically the origin of magnetism in nanocrystalline-undoped ceria films. Our results are consistent with density-functional calculations showing that both oxygen and cerium vacancies lead to ferromagnetism. Although the number of cerium vacancies is smaller than that of oxygen vacancies, the relatively high magnetic moment of the former might result in a substantial contribution to the magnetic properties. Diluted defect magnetism is suggested as a universal feature of ferromagnetism in nonmagnetic oxides without magnetic impurities.

The authors report ferromagnetism at room temperature in Co doped $\mathrm{Ce}{\mathrm{O}}_{2-\delta }$ thin films grown by pulsed laser deposition on $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3$ and Si substrates. On $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3$ ceria is epitaxied and displays a high crystalline quality. On Si the films are textured with a dominant orientation. While the ferromagnetism is little affected by the amounts of structural defects, it depends sensitively on the oxygen pressure during growth and annealing. This indicates that oxygen vacancies could be involved in the magnetic coupling between Co ions. Furthermore, the epilayers grown on $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3$ display a large magnetic anisotropy with an out of plane easy axis.

By using heteroepitaxy on two different GaAs templates, we have investigated the impact of anisotropic strain on the magnetocaloric effect (MCE) of MnAs. The temperature range, spread around room temperature, and the maximal MCE position are markedly different in the two epitaxial systems. Simulated MCE curves, obtained from a model based on the mean-field approximation, are in good agreement with the experimental data, indicating that the entropy variation is magnetic in origin. These results illustrate how strain can be used to tune the MCE in materials with coupled structural and magnetic phase transition and suggest that the MCE of MnAs may find applications in microelectronic circuitry.