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In the present paper, giant magnetostrictive (GMS) thin films have been investigated for future microelectromechanical systems (MEMS) purposes. To this end, flexural and torsional motions have been studied in low-field anisotropic GMS single-domain state (SDS) exchange-coupled TbFe-FeCo multilayers (ECML). The magnetoelastic (ME) coefficient [b.sup.[gamma],2] depends strongly on the ECML structures, compositions, and sputtering deposition parameters. GMS multilayers with a high [b.sup.[gamma],2]] (18 MPa for Tb[Fe.sub.2]/[Fe.sub.0.6][Co.sub.0.4] compared to 11 MPa for Tb[Fe.sub.2]/Fe) were obtained with or without an in-plane easy axis with a controlled direction, and without any annealing postprocess. Dynamical excitations of the actuators have been investigated under various conditions. An enhancement up to a factor 5 of the oscillations compared to the TbFe-Fe muitilayers is observed with the possibility to tune the flexural/torsional dynamical behavior of these cantilevers. The corresponding very large dynamical ME susceptibility of these improved uniaxial ECML gives the possibility to control GMS MEMS with further reduction of the excitation field down to a few oersteds. Index Terms--Actuators, dynamics, giant magnetostriction (GMS), multilayer, spin reorientation transition (SRT), thin films.

A complex study of the electron transport and magnetic characteristics of epitaxial manganite films La0.7Ba0.3MnO3 (LBMO) was carried out under conditions of the crystal structure tension caused by a mismatch between the parameters of the LBMO crystal and the substrate. The epitaxial thin films with the thickness 40–100 nm were grown by pulsed laser deposition at T = 700–800 °C in pure oxygen pressure 0.3–1 mbar. The substrates (110) NGO, (001) STO, (001) LAO, and (001) LSAT were used. By comparison of the lattice parameter of LBMO targets with substrate's one, the lattice mismatches were derived. We used substrates in which the lattice parameter was less than for the LBMO crystal one. It is shown that the temperature dependence of the film resistance in the low-temperature region does not depend on the film stress and is in good agreement with the calculation that takes into account the interaction of carriers with magnetic excitations in the presence of strongly correlated electron states. A nonmonotonic temperature dependence of the resistance of an LBMO film deposited on ferroelectric crystals PMN-PT that was observed. This feature is typical for manganites, and indicating the presence of ferromagnetism in the system was observed. [ABSTRACT FROM AUTHOR]

The Magneto-Optic Kerr Effect (MOKE) technique has been used to investigate the magnetic properties of Ni thin films, with thickness t ranging from 9 to 163 nm, evaporated onto several substrates (glass, Si (111), mica and Cu) with and without an evaporated Cu underlayer. The MOKE observations were correlated with the surface morphology inferred from Scanning Electron Microscope images and with the structural properties (grain size and strain). Some interesting behaviors of the coercive field (with values in the 2 to 151 Oe range), the squareness (between 0.1 and 0.91) and the saturation field (25–320 Oe) are observed as a function of t , the substrate and the Cu underlayer. A thickness-dependent stress-induced anisotropy is found in these films. The differences between the present MOKE results and the ones obtained from the Vibrating Sample magnetometer (VSM) are highlighted. The former describe the surface magnetism of these systems, while the latter are attributed to the whole volume of the sample. [ABSTRACT FROM AUTHOR]

Two series of Fe thin films have been electrodeposited onto polycrystalline porous Al substrates using two baths: iron chloride (FeCl) and iron sulfate (FeSO). The texture, strain, and grain size values have been derived from X-ray diffraction experiments. Scanning electron microscopy has been employed for surface morphology. The magnetic properties were inferred from hysteresis curves that were obtained from a vibrating sample magnetometer; the external magnetic field was applied in different directions of the film plane and also perpendicular to the film. Hysteresis curves have been obtained at low temperatures (120 K (−153 °C) to room temperature). We investigate the effects of Al porosity, bath type, and deposition rate on physical properties of these Fe films. A correlation between the structural and magnetic properties is made. Different mechanisms responsible for the coercive field ( H ) behavior have also been investigated. [ABSTRACT FROM AUTHOR]

Ni thin films have been deposited by thermal evaporation onto glass, Si, Cu, mica, and AlO substrates with and without a Cu underlayer. The Ni thicknesses, t, are in the 4 to 163 nm range. The Cu underlayer has also been evaporated with a Cu thickness equal to 27, 52, and 90 nm. The effects of substrate, Ni thickness, and the Cu underlayer on the magnetic properties of Ni are investigated. Magnetic properties were inferred from the vibrating sample magnetometer (VSM) set-up. The substrates induce not only different coercive field H values but also the origins of the H values are different. The squareness S depends on substrate and t and seems to be relatively large in Ni/glass and Ni/Cu, and small in Ni/Si and Ni/mica. The Cu underlayer leads to an overall increase of H and the saturation H and to a decrease in the remnant magnetization; the increase in H may be related to a stress-induced anisotropy in Ni/Cu/substrates. [ABSTRACT FROM AUTHOR]

Hybrid giant magnetostrictive-piezoelectric film/film structures exhibiting magnetoelectric (ME) effect associated with a magnetic instability of the spin reorientation transition type are presented. We first present the theoretical study of a clamped beam actuator composed of a piezoelectric layer on a substrate actuated by a magnetostrictive layer. The actuator is a polished 50 μm thick 18×5 mm2 silicon substrate coated by an electrode, aluminum nitride, and magnetostrictive nanostructured layer. A ME coefficient of 30 V Oe-1 cm-1 at a 35 KHz longitudinal resonance was measured. Nonlinear excitation of this mode showed a “nonlinear” dynamic ME coefficient of 4 V Oe-1 cm-1. [ABSTRACT FROM AUTHOR]