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Fe films with thicknesses between 17 and 95 nm were grown with a nano-sheet morphology, which enabled their high uniaxial magnetic, transport, and optical in-plane anisotropies. The top edge of the nano-sheets was directly visualized as nano-string-like structures of approximately 12.5–14 nm width and 100–300 nm length. The hysteresis loops showed a clear easy direction of magnetization in the longitudinal direction of the nano-sheets, whereas the hard direction loops were anhysteretic, with no remanence and zero coercive field. The anisotropy field exhibited values between 70 and 111 kA/m depending on the thickness of the films, with the maximum value corresponding to a 34 nm thick sample. The resistance of the films was also found to be highly anisotropic. The ratio ( R⊥– R||)/ R|| was ≈86%, with R|| and R⊥ being the resistances in the parallel and perpendicular directions of the nano-sheets, respectively. Likewise, the reflectivity of the samples behaved anisotropically; the ratio ( IReflmax– IReflmin)/ IReflmax of the intensity of reflected light by the films reached up to 61% for 34 nm thick samples, achieving the maximum value, IReflmax, when the plane of the incident light coincided with the direction of the nano-sheets and the minimum, IReflmin, when this plane was perpendicular to the direction of the nano-sheets. The origin of these anisotropic behaviors was established. These anisotropic films with high magnetization and high uniaxial anisotropies at the nanoscale can be useful for microelectronics applications, for devices such as magnetic sensors and transducers, or for ultrahigh frequency inductors.

The magnetic and transport properties of pulsed laser-deposited Co100−x–Cux thin films were tailored through their nano-morphology and composition by controlling for the deposition geometry, namely normal or oblique deposition, and their Cu content. All films were composed of an amorphous Co matrix and a textured growth of Cu nanocrystals, whose presence and size d increased as x increased. For x = 50, all films were superparamagnetic, regardless of deposition geometry. The normally deposited films showed no in-plane magnetic anisotropy. On the contrary, controllable in-plane uniaxial magnetic anisotropy in both direction and magnitude was generated in the obliquely deposited films. The magnetic anisotropy field Hk remained constant for x = 0, 5 and 10, Hk ≈ 35 kAm−1, and decreased to 28 and 26 kAm−1 for x = 20 and 30, respectively. This anisotropy had a magnetostatic origin due to a tilted nano-sheet morphology. In the normally deposited films, the coercive field Hc increased when x increased, from 200 (x = 0) to 1100 Am−1 (x = 30). In contrast, in obliquely deposited films, Hc decreased from 1500 (x = 0) to 100 Am−1 (x = 30) as x increased. Activation energy spectra corresponding to structural relaxation phenomena in obliquely deposited films were obtained from transport property measurements. They revealed two peaks, which also depended on their nano-morphology and composition.

Thin films of Co-rich transition metal or metal Co–MT (MT = V, Cr, Cu, Zn, Cd, Hf) compounds were fabricated as a superposition of oblique nano-sheets (≈300 x 80 × 5 nm for each nano-sheet) from a mixture of Co and MT plasmas. Because the X-ray diffraction patterns of all of the films showed a similar nano-crystalline microstructure, the oblique nano-sheets were visualized by high-resolution transmission electron microscopy. This nano-morphology generated strong in-plane uniaxial magnetic anisotropy, UMA, as we explained in this work, for all the as-deposited films. The evolution of this magnetic anisotropy was studied at temperatures up to 450 °C. Three different cases were observed after these heat treatments depending on the MT component of the film: (1) UMA was lost for temperatures ≈ 400 °C, (2) UMA retained the same value until the highest temperature was reached, or (3) UMA was enhanced by a factor greater than 2 for the highest temperature. This behavior can be explained by considering of the various processes of structural relaxation and crystallization produced by heat treatment and affected by the nano-sheet morphology.

Thin films of Co-Hf (≈ 86-14 % at.) were grown over Si micro-cantilevers using a glancing-angle deposition technique. A controlled easy direction of magnetisation (anisotropy field μoHk ≈ 0.1 T) in the longitudinal or in the transverse direction of the micro-cantilevers was generated. The mechanical properties of the films under the action of a magnetic field were opposite depending on the magnetisation’s easy direction: i) their deflection was either zero or the maximum value depending on the direction of the applied magnetic field with respect to the parallel or transverse easy direction of magnetisation; ii) the shift in the resonance frequency under a longitudinal or transverse magnetic field was also different depending on the longitudinal or transverse easy direction of magnetisation. The use of these coated devices with micromagnet-like films for sensors and transducers is discussed.

Hard magnetic MnBi films were fabricated using pulsed laser deposition (PLD). The films consisted of Mn/Bi bilayers and the thickness of each sample constant was 185 nm. The number of bilayers (5 to 80 bilayers) and consequently, the thickness of the Mn and Bi layers changed among the different samples, although the proportion of Mn and Bi remained constant in each bilayer. The structural and morphological changes in the Mn/Bi multilayered films were produced by thermal treatments and were monitored by measuring the change in their resistance as a function of the temperature. These measurements, along with the magnetic measurements, allowed us to determine the optimum heat treatments that induced the formation of the low temperature (LT) α-MnBi phase. A maximum value of both the magnetisation (460 emu/cm3) and the maximum BH product (46 kJ/m3) was observed in the sample with 40 bilayers, showing, in addition, a magnetic anisotropy, wherein the easy magnetisation direction was predominantly perpendicular to the plane of the sample. A detailed explanation of these changes and of the atomic diffusion processes present for such optimisation has been achieved.

Soft magnetic Co films, with a grain size of 1–2nm and thickness between ≈1.3 and tens of nanometers were pulsed laser deposited on rotating metallic wire substrates, conferring them cylindrical geometry. These films showed a magnetostrictive property, making it possible to measure and study the magnetoelastic inverse Wiedemann effect, (IWE) of the longitudinal magnetic flux in the film as a function of the circular applied magnetic field, Φz−Hϕ. The IWE of these films was explained by the assumption of magnetic wall nucleation and magnetization rotation processes. This explanation allowed us to establish the relation of Φz with the spontaneous magnetization Ms and with the film's thickness. Then using the measured Φz and the known value of Ms: (1) we determine the thickness of the film by means of an inductive method; (2) we analyze the inaccuracy of the determined film thickness; (3) we achieve the limit of tfilm,min=1.3±0.3nm in thickness for measuring the films’ magnetic properties.

Cylindrical soft magnetic Co films, nanostructured with a grain size of 1–2 nm and between and 90 nm in thickness, were produced by the pulsed laser deposition technique. These films showed a magnetostrictive property. The magnetoelastic inverse Wiedemann effect, or IWE, of longitudinal magnetization as a function of the circular applied magnetic field, Mz–H, was measured. The IWE made it possible to explain the magnetization processes according to an initial reversible rotation of the magnetization followed by magnetic wall nucleation and propagation. A magnetization rotation model allowed us to compare the reversible part and the first irreversible magnetization processes corresponding to the IWE. In this way, the values of the helical magnetic anisotropy, Kh, due to the helical stresses, σh, generated by an applied torque to the films, were determined. A linear increase of the nucleating magnetic wall field, HN, with the applied torque, or with σh, was observed. In addition, the IWE made it possible to establish the non-dependence of the saturation magnetostriction constant, λs, on the sample thickness and to determine the value of this negative isotropic .

The magnetic susceptibility of Fe–Al off-normal pulsed laser deposited thin films was measured at ultra high frequencies, UHF. Different Fe 1− x –Al x films from pure Fe to x = 0.2 Al were prepared. The films were ≈40 nm thick and non-crystalline peaks were detected by the X-ray diffractometry studies. The magnetization of the films remained between 2.0 and 1.8 T for composition less than or equal to 20% Al. A magnetic anisotropy, from H k ≈ 18 Oe for pure Fe to H k ≈ 130 Oe for 20% Al was measured. These samples exhibited a well-defined ferromagnetic resonance at frequencies between ≈2.0 GHz and 3.8 GHz depending on composition. The broad resonance peaks had a width, at half maximum, w h , in the interval from 2.5 GHz to 4.0 GHz depending on Al content. After fitting the magnetic hysteresis loops using a simple distribution of anisotropy values, we used the Landau–Lifshitz–Gilbert equation to fit the UHF magnetic susceptibility. From this last fit we obtained a high damping coefficient value (≈4 times higher than that corresponding to Co or CoFe films), explaining this broad ferromagnetic resonance of these Fe 1− x –Al x films.

Amorphous Co pulsed laser off-normal deposited films have shown uniaxial magnetic anisotropy. They have exhibited values of the anisotropy field between H u =12 and 770 Oe depending on the deposition angle and on the film thickness. We show for the first time the different like nano-string structures—8 to 20 nm width by 120 nm large—of these films. Also the magnetic domain pictures—sharpness zigzag charged walls for high magnetic anisotropic films and big zigzag Bloch walls for films with low anisotropy—are presented.

Si micro-cantilevers were coated with Co nano-strings, which were simultaneously grown and sculpted during off-normal pulsed laser deposition. The surface morphology of micro-cantilevers with longitudinal or transverse nano-strings was analysed by scanning tunnelling microscopy. Magnetic anisotropy was detected with a magnetization direction parallel to the nano-strings. The two micro-cantilever types exhibited different mechanical behaviours when placed in a non-uniform magnetic field. By varying the relative position of the micro-cantilever with respect to the gradient direction of this field, a split in the resonant frequency shift of the micro-cantilevers was generated, depending on the direction of magnetic anisotropy. Discrimination was achieved between the micro-cantilevers with transverse nano-strings and the micro-cantilevers with longitudinal nano-strings. The lowest limit of magnetic moment for distinction between these covered micro-cantilevers was 10 − 8 emu. The possible benefits of these magneto-mechanical properties for the biological, chemical and physical applications of some nano-mechanical devices are pointed out.

CoP multilayers grown over Cu wires exhibit magnetoimpedance phenomenon. The change in the real part of the measured voltage is V R = [ V ( H = 0 Oe)- V ( H max )]/ V ( H max ) ≈ 3300%( I rms = 500 mA, 90 kHz); the maximum d V R /d H , is 1280%/Oe at H DC = 1.2 Oe. These quantities are enhanced if the wire is subjected to an angular deformation by means of a torque applied to the wire; V R ≈ 7000% and d V R /d H ≈ 2400%/Oe, are found at 9 and 1.2 Oe, respectively, for a 90° twisted sample, produced by the change in the magnetic anisotropy direction, from the longitudinal to the helical one.

In this work, we report the magnetic properties of a set of magnetic multilayers whose particular nanostructure allows control of their in-plane, uniaxial magnetic anisotropy value and consequently the magnetic susceptibility measured at ultra high frequencies. Particularly, two sets of samples with the compositions ((Co15 nm-54°) (Cox nm-0°) (Ta6 nm-54°)) n and ((Fe10 nm-54°) (Fex nm-0°) (Ta6 nm-54°)) n where n is the number of trilayers. In every sample, the obliquely and normally deposited ferromagnetic layers were strongly exchange-coupled. Consequently, the value of the uniaxial in-plane magnetic anisotropy could be controlled by changing the thickness of the normally deposited layer (x). Subsequently, the magnetic susceptibility of the samples could be tailored. Thus, the ferromagnetic resonance frequency value may be controlled and increased to up to 6.3 GHz for the samples with larger magnetic anisotropy values.

Over a 60 μm film with perpendicular anisotropy, a composition modulated multilayer, of the same material, has been grown. Investigations using Bitter domain configuration observations and surface hystetic loop measurements using magneto-optic Kerr rotation show that the multilayer magnetization process is coupled with the underlayer anisotropy for multilayer thickness of the order of the bulk stripes domain width.

Amorphous soft magnetic CoP electrolytic multilayers have been obtained with a controlled surface magnetic anisotropy. The surface magnetization easy direction can be continuously altered from an initial perpendicular position to a final arrangement within the longitudinal plane. This continuous change of magnetization direction is controlled during the sample production stage and, therefore, there is no need to subject the films to subsequent treatments such as, for example, thermal, stress, or magnetic field annealing. The magnetic domain configurations, as observed by means of the Bitter technique, have revealed a continuous variation from an initial stripe domain structure to a final situation in which the magnetization lies within the plane of the films and magnetic domain walls are observed. The magneto-optic behavior of these multilayers has also revealed this continuous evolution from an initial perpendicular easy direction for the magnetization to a configuration in which the surface magnetizatio...

CoP amorphous samples, electrodeposited on copper wires and exhibiting a longitudinal magnetic anisotropy, show a spontaneous Matteucci effect once the substrate has been subjected to torque. This induces an easy axis to allow for magnetization to occur, breaking away from its original longitudinal direction. The magnetic domain structures, as observed by the Bitter technique, revealed that the anisotropy changes direction, rotating gradually from its initial longitudinal position to a 45° helix, as the torque was increased. The reversible part of the circular magnetization switching curves, set against the longitudinal magnetic field, was fitted by assuming a magnetization rotation model in which constant anisotropic magnitude values were hardly modified, while allowing changes in direction.

CoP electrolytic monolayers and multilayers were grown over copper wires using a constant or pulsed electrical current density, exhibiting radial or planar anisotropy, respectively. Over the surface of a monolayer, multilayers of different thicknesses were deposited. The surface radial anisotropy evolves to a planar one as the overlayer thicknesses increase. The surface magnetization is coupled with the bulk anisotropy for overlayer thickness up to ≈ 2 μm.