Abstract
Flexible materials have brought up a new era of application-based research in stretchable electronics and wearable devices in the last decade. Tuning of magnetic properties by changing the ...curvature of devices has significant impact in the new generation of sensor-based technologies. In this work, magnetostrictive FeGa thin films have been deposited on a flexible Kapton sheet to exploit the magneto-elastic coupling effect and modify the magnetic properties of the sample. The FeGa alloy has high magnetostriction constant and high tensile strength making its properties susceptible to external stress. Tensile or compressive strain generated by the convex or concave states influence the uniaxial magnetic anisotropy of the system. Low temperature measurements show a hard magnetic behavior and the presence of exchange-bias effect after field cooling to 2 K. The results obtained in this study prove essential for the development of flexible electronics.
An important research effort on the design of the magnetic particles is increasingly required to optimize the heat generation in biomedical applications, such as magnetic hyperthermia and ...heat-assisted drug release, considering the severe restrictions for the human body's exposure to an alternating magnetic field. Magnetic nanoparticles, considered in a broad sense as passive sensors, show the ability to detect an alternating magnetic field and to transduce it into a localized increase of temperature. In this context, the high biocompatibility, easy synthesis procedure and easily tunable magnetic properties of ferrite powders make them ideal candidates. In particular, the tailoring of their chemical composition and cation distribution allows the control of their magnetic properties, tuning them towards the strict demands of these heat-assisted biomedical applications. In this work, Co
Zn
Fe
O
Li
Zn
Fe
O
and ZnFe
O
mixed-structure ferrite powders were synthesized in a 'dry gel' form by a sol-gel auto-combustion method. Their microstructural properties and cation distribution were obtained by X-ray diffraction characterization. Static and dynamic magnetic measurements were performed revealing the connection between the cation distribution and magnetic behavior. Particular attention was focused on the effect of Co
and Li
ions on the magnetic properties at a magnetic field amplitude and the frequency values according to the practical demands of heat-assisted biomedical applications. In this context, the specific loss power (SLP) values were evaluated by ac-hysteresis losses and thermometric measurements at selected values of the dynamic magnetic fields.
Abstract
Artificial magnetoelectric materials possess huge potential to be utilized in the development of energy efficient spintronic devices. In the past decade, the search for a good ...ferromagnetic/ferroelectric combination having the ability to create high magnetoelectric coupling, created new insights and also new challenges. In this report, the magnetoelectric effect is studied in the FeGa/PMN-PT(001) multiferroic heterostructures in the presence of electric fields via strain-mediated effects. The formation of magnetic anisotropy in FeGa is observed after changing the polarization of PMN-PT to out-of-plane orientations. The magnetic domain structures forming during the magnetization reversal were studied in compressive, tensile and remanent strained states. The changes in the magnetic properties were reversible after each cycling of the electric field polarity, hence creating a non-volatile system. The control of magnetization switching sustained by an ON–OFF electric field makes our multiferroic heterostructure suitable for application in low-power magnetoelectric based memory applications.
Sputtering and electrodeposition are among the most widespread techniques for metallic thin film deposition. Since these techniques operate under different principles, the resulting films typically ...show different microstructures even when the chemical composition is kept fixed. In this work, films of Fe
70
Pd
30
were produced in a thickness range between 30 and 600 nm, using both electrodeposition and sputtering. The electrodeposited films were deposited under potentiostatic regime from an ammonia sulfosalicylic acid-based aqueous solution. Meanwhile, the sputtered films were deposited from a composite target in radio frequency regime. Both approaches were proven to yield high quality and homogenous films. However, their crystallographic structure was different. Although all films were polycrystalline and Fe and Pd formed a solid solution with a body-centered cubic structure, a palladium hydride phase was additionally detected in the electrodeposited films. The occurrence of this phase induced internal stress in the films, thereby influencing their magnetic properties. In particular, the thickest electrodeposited Fe
70
Pd
30
films showed out-of-plane magnetic anisotropy, whereas the magnetization easy axis lied in the film plane for all the sputtered films. The domain pattern of the electrodeposited films was investigated by magnetic force microscopy. Finally, nanoindentation studies highlighted the high quality of both the sputtered and electrodeposited films, the former exhibiting higher reduced Young's modulus and Berkovich hardness values.
Nanoscale magnetic materials are the basis of emerging technologies to develop novel magnetoelectronic devices. Self-assembly of polystyrene nanospheres is here used to generate 2D hexagonal dot ...arrays on Fe
50
Pd
50
thin films. This simple technique allows a wide-area patterning of a magnetic thin film. The role of disorder on functional magnetic properties with respect to conventional lithographic techniques is studied. Structural and magnetic characteristics have been investigated in arrays having different geometry (i.e. dot diameters, inter-dot distances and thickness). The interplay among microstructure and magnetization reversal is discussed. Magnetic measurements reveal a vortex domain configuration in all as-prepared films. The original domain structure changes drastically upon thermal annealing performed to promote the transformation of disordered A1 phase into the ordered, tetragonal L1
0
phase. First-order reversal magnetization curves have been measured to rule out the role of magnetic interaction among crystalline phases characterized by different magnetic coercivity.
Magnetic vortices have been an interesting element in the past decades due to their flux-closure domain structures which can be stabilized at ground states in soft ferromagnetic microstructures. In ...this work, vortex states are shown to be nucleated and stabilized in Fe80Ga20 and Fe70Ga30 disks, which can be an upcoming candidate for applications in strain-induced electric field control of magnetic states owing to the high magnetostriction of the alloy. The magnetization reversal in the disks occurs by the formation of a vortex, double vortex or S-domain state. Micromagnetic simulations have been performed using the FeGa material parameters and the simulated magnetic states are in good agreement with the experimental results. The studies performed here can be essential for the use of FeGa alloy in low-power electronics.
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•Control of perpendicular anisotropy through thermal annealing.•Magnetic stripes rotation along equivalent directions possible only with a large enough applied magnetic ...field.•Threshold field for stripes rotation proportional to perpendicular magnetic anisotropy.•Pinning of magnetic domains due to the reversal of the perpendicular component of their magnetisation.
Fe78Si9B13 thin films having a controlled weak perpendicular anisotropy resulting in dense stripe domain configuration have been prepared to investigate their rotatable anisotropy properties. Vector vibrating sample magnetometry, an innovative field-dependent magnetic force microscopy, and ferromagnetic resonance techniques have been jointly exploited to correlate the perpendicular anisotropy to the threshold field value that must be overcome to induce the stripes realignment. A linear relationship between these two quantities is found. The presence of the threshold field is attributed to the portions of the samples whose magnetisation must flip its perpendicular component during a rotation process, therefore encountering the energy barrier of the perpendicular anisotropy.
Electronics and soft robotics demand the development of a new generation of hybrid materials featuring novel properties. Among these, remarkable mechanical properties are required to sustain ...mechanical stresses, and electrical and magnetic properties are essential to design the devices’ interface. In this study, a hybrid material is presented, consisting of a spider silk thread, providing mechanical robustness, coated with a layer of a magnetostrictive FeCo alloy, which ensures both electrical conductivity and stress‐sensitive magnetic properties. The durability and the homogeneity of the composite are validated, as well as its ability to respond to magnetic and mechanical stimuli. Despite the coating, the soft nature of the silk and its mechanical performances are preserved. The magnetic study reveals that the magnetic behavior of the film is strongly affected by the silk thread–FeCo layer interaction, especially under mechanical stresses. Indeed, when the composite is subjected to tensile strain, the magnetic signal changes accordingly, indicating that the layer–silk interaction is maintained and can be exploited to reveal the tensional state of the sample even under severe cycles. Therefore, the presented hybrid material is a flexible fiber with properties that are suitable for magneto‐electronics applications, e.g., magnetic actuators as well as strain/stress sensors.
Mechanically robust spider silk threads are coated with a magnetostrictive FeCo alloy that provides electrical conductivity and stress‐sensitive magnetic properties. The hybrid system here designed is soft, durable, and promptly responds to magnetic and mechanical stimuli. The complete mechanical, electric, and magnetic characterization shows that this spider silk based component can be used for soft electronics and robotics applications.
•Iron oxide nanoparticles inside SBA-15 modified with amino groups as glyphosate sorbent.•Quantitative removal of glyphosate in real water matrices.•Complete regeneration of the sorbent through ...diluted NaOH solution.
Iron oxide clusters were incorporated into amino-functionalized SBA-15 in order to obtain a magnetically recoverable adsorbent. The physical-chemical properties of the material were characterized by FE-SEM, STEM, XRD, TGA, XPS, FT-IR and acid-base titration analysis.
Iron oxide nanoparticles were uniformly dispersed into the pore of mesoporous silica and that the adsorbent is characterized high specific surface area (177m2/g) and accessible porosity.
The sorbent was successfully tested for the removal of glyphosate in real water matrices. Despite the significant content of inorganic ions, a quantitative removal of the contaminant was found. The complete regeneration of the sorbent after the adsorption process through diluted NaOH solution was also proved.
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