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Bi 2 Te 3 is the most commonly used thermoelectric material in modern solid-state refrigerators and power generators based on this basic principle. Due to predictions of significant improvements in their efficiency by using nanostructured materials, a thorough study on thin films and nanowires deposited by the electrodeposition method are here presented. The study of the deposition applied potential effect on the morphology, stoichiometry and crystallinity of both thin films and nanowires has been conducted. The morphology and stoichiometry was found to highly depend on the deposition potential, where by increasing it one was able to accurately control the Te% content of the deposits. X-ray diffraction measurements have shown the presence of a strong relation between the material's crystallinity and the deposition potential, where samples ranged from monocrystalline, at very low potentials, to almost completely amorphous, at high potentials. Finally, nanowire diameters were seen to diminish with the applied potential, in conjunction with the general array. [ABSTRACT FROM AUTHOR]

The influence of thermal cycling on the microstructure, magnetic phase transition and magnetic entropy change of a Gd 5 Si 1.3 Ge 2.7 thin film up to 1000 cycles is investigated. The authors found that after 1000 cycles a strong reduction of the crystallographic phase responsible for the magnetostructural transition (Orthorhombic II phase) occurs. This is attributed to chemical disorder, caused by the large number of expansion/compression cycles that the Orthorhombic II phase undergoes across the magnetostructural transition. The suppression of the magnetostructural transition corresponds to a drastic decrease of the thin film magnetic entropy change. These results reveal the importance of studying the thermal/magnetic cycles influence on magnetostructural transitions as they can damage a real-life device. [ABSTRACT FROM AUTHOR]

• Multiferroic Ca 3 Mn 2 O 7 thin films were prepared by laser ablation on SrTiO 3 substrates. • The conditions for the stabilization of the Ca 3 Mn 2 O 7 phase were determined. • Presence of A2 1 am ferroelectric phase and substrate-induced polar distortion enhancement. • Magnetoelectric and magnetically induced dipolar correlations observed in the samples. • Substrate-induced strain favours multiferroicity in Ca 3 Mn 2 O 7 films. Multiferroic Ruddlesden-Popper Ca 3 Mn 2 O 7 thin films were prepared by laser ablation on SrTiO 3 substrates. For low laser fluences and high oxygen pressures, the films assumed the CaMnO 3 Pnma orthorhombic structure. However, by increasing fluence and decreasing the oxygen pressure, the Ca 3 Mn 2 O 7 phase is achieved through a post-deposition annealing treatment. Furthermore, the ferroelectric phase A2 1 am was observed in the films, along with the orthorhombic Acaa phase, with a preferential [111] growth orientation and substrate-induced enhancement of the polar ferroelectric distortion. The dielectric permittivity shows dispersion described by the Havriliak-Negami function, and from fits to the curves, a different behavior was observed in the antiferromagnetic region. Also, the Kohlrausch-Williams-Watts stretched exponential parameter showed an abrupt decrease below ∼110 K, near the Néel temperature. This indicates the presence of magnetoelectric interactions and magnetically induced enhancement of dipolar correlations in the samples, favoring substrate-induced strain to enhance multiferroicity in these films. [Display omitted] [ABSTRACT FROM AUTHOR]

Due to the emerging cooling possibilities at the micro and nanoscale, such as the fast heat exchange rate, the effort to synthesize and optimize the magnetocaloric materials at these scales is rapidly growing. Here, we report the effect of different thermal treatments on Gd 5 Si 1.3 Ge 2.7 thin film in order to evaluate the correlation between the crystal structure, magnetic phase transition and magnetocaloric effect. For annealing temperatures higher than 773 K, the samples showed a typical paramagnetic behavior. On the other hand, annealing below 773 K promoted the suppression of the magnetostructural transition at 190 K, while the magnetic transition around 249 K is not affected. This magnetostructural transition extinction imparts reflected in the magnetocaloric behavior and resulted in a drastic decrease in the entropy change peak value. Nevertheless, an increase in 25% of the T C and an increasing Δ T FWHM from 23 to 49 K of its operation temperature interval, Δ T , upon annealing, are crucial for future application in magnetic refrigeration. [ABSTRACT FROM AUTHOR]

Abstract: This work is addressed to studying GdMnO3 thin films, prepared by a chemical solution method on oriented Pt substrates. Alterations regarding structure and magnetic response of both ceramics and single crystals show that the behaviour of the as-prepared films can be understood by assuming a continuously changing of the in-plane stress state in the film induced by mechanical coupling with the substrate. The emerging of a ferromagnetic response in the thin films is a consequence of the structural deformations induced by matching both film and substrate during the growth process, which alters the balance between competitive antiferromagnetic and ferromagnetic interactions. [Copyright &y& Elsevier]

Abstract: The influence of stress on the magnetic properties of BaTiO3–CoFe2O4 nanocomposites deposited by laser ablation on platinum covered Si(001) substrates, was characterized. The cobalt ferrite phase was under compressive strain in the growth direction that progressively relaxed as its concentration increased. A stress induced perpendicular magnetic anisotropy was observed, that decreased with increasing CoFe2O4 content, due to the relaxation of stress in the films. [Copyright &y& Elsevier]