Barium strontium titanate (Ba_0.8Sr_0.2TiO₃, BST) nanocrystalline ceramics have been synthesized by high energy ball milling. As the sintering temperature increases from 1200 °C to 1350 °C, the average grain size of BST ceramics increases from 86 nm to 123 nm. The X-ray diffraction (XRD) studies show that these ceramics are tetragonal. The phase and grain size of the sintered pellets have been estimated from the XRD patterns, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images. The effect of grain size on dielectric and ferroelectric properties is studied. The dielectric and piezoelectric parameters are greatly improved at room temperature with increase in grain size. The Curie transition temperature is found to shift slightly towards higher temperatures as the grain increases from 86 nm to 123 nm. The coercive field decreases and the remnant polarization and spontaneous polarization increase as the grain size of BST nano ceramics increases. These ceramics are promising materials for tunable capacitor device applications.

In perpendicularly magnetized Pd/Co/Pd trilayers, the hydrogenation not only increased Kerr signal but also significantly enhanced the magnetic coercivity (H_C) by 17%. The reversibility was demonstrated by cyclic H₂ exposure. The time constants of hydrogen absorption and desorption effect on H_C range from tens to hundreds seconds, depending on the H₂ gas pressure. The magneto-optical Kerr signal and magnetic coercivity was simultaneously recorded during H₂ absorption and desorption. These multifarious signals respond differently and provide a detailed understanding of hydrogenation effect on the functional Pd/Co/Pd trilayers.

Formation of monodispersed Co nanoclusters on a single-crystal $\mathrm{S}{\mathrm{i}}_{\mathrm{3}}{\mathrm{N}}_{\mathrm{4}}$ dielectric film at room temperature is reported. A remarkably narrow size distribution with the average size of $\sim 30\mathrm{C}\mathrm{o}$ atoms has been obtained. We have confirmed that the average size of Co nanoclusters is independent of the Co coverage and the cluster areal density linearly proportions to the Co deposition amount even at high coverages. Also, we have found that Co nanoclusters deposited on $\mathrm{S}{\mathrm{i}}_{\mathrm{3}}{\mathrm{N}}_{\mathrm{4}}$ are thermally stable with respect to cluster aggregation/coalescence. We propose that this novel phenomenon is a quantum size effect, manifested by local energy minima in the electronic shell structure of Co quantum dots.

The effect of hydrogenation on a 14 nm Co₁₄Pd₈₆/Al₂O₃(0001) thin film was investigated on the basis of the magnetooptical Kerr effect. After exposure to H₂ gas, the squareness of the hysteresis loop showed a large transition from approximately 10% to 100% and the saturation Kerr signal was reduced to nearly 30% of the pristine value. The reversibility of the transition was verified and the response time was within 2–3 s. These observations indicate that the hydride formation transformed the short-range coupled and disordered magnetic state of the Co₁₄Pd₈₆ film to a long-range-ordered ferromagnetic state and induced appreciable decrease in the magnetic moment. The enhanced long-range-ordering and the reduction of the magnetic moment were attributed to the change of electronic structure in Co₁₄Pd₈₆ with hydrogen uptake.

The ultrathin ${\mathrm{Co}}_x{\mathrm{Ni}}_{1-x}/\mathrm{Cu}\mathrm{}\left(100\right)\mathrm{}$ alloy films with low Co concentration $x<~10\%$ was prepared for probing the effect of the d-band filling on the magnetic behavior. The perpendicular magnetization was observed only for films with $x<\mathrm{}10\%.\mathrm{}$ The spin-reorientation transition from the in-plane to perpendicular orientation was found to be extremely sensitive to the Co concentration. The critical thickness for the spin reorientation transition was changed drastically from 7.5 to 17.5 ML by varying x from 0 to $8\hspace{0.5em}\%.\mathrm{}$ Since no significant change in structure and surface morphology was accompanied, these findings may be attributed to the critical influence of the d-band filling on the magnetic anisotropy at variation of alloy composition.