Switching Field Distribution Research Articles

Structural evolution and magnetic, optical, and optoelectronic properties changes in annealed Co0.5Sr0.5Fe2O4 nanoparticles: A comprehensive study

A sample of Co0.5Sr0.5Fe2O4 nanoparticles was synthesized by the coprecipitation technique to explore the effect of annealing on the structure and some physical properties of the produced material. The coprecipitated sample consists of an orthorhombic strontium carbonate phase and the required cubic Co0.5Sr0.5Fe2O4. Annealing at elevated temperatures (900 °C) leads to the formation of cubic and hexagonal phases. This crystal structure was confirmed by X-ray diffraction analysis (XRD). The accuracy of the cation distribution of the cubic phase determined from the Rietveld analysis of XRD patterns is demonstrated by matching the experimental and theoretical lattice constants. There are several noticeable changes in aspects as the annealing temperature goes up. The transmission electron microscopy (TEM) images indicated that heating substantially affects the growth and densification of the smaller nanoparticles. There is a drop in the longitudinal and transverse wave velocities, bulk, rigidity, Young's moduli, Poisson ratio (σ), and Debye temperature (θD) with annealing and grain growth. The saturation magnetization and coercive field are enhanced with annealing. The particle size distribution calculated from TEM is confirmed and supported by the switching field distribution. The indirect optical bandgap energy (Eg) decreased with annealing. The present study concentrated on the thermal treatment impacts on various optical parameters, such as the refractive index and extinction coefficient. The optoelectrical parameters, such as the dielectric constant, dielectric loss, and optical and electrical conductivity, were extensively investigated, giving valuable insights, and their results were interpreted. These findings suggest potential applications in magnetic storage, sensors, and optoelectronics fields.

Investigation of magnetic domain interactions and switching mechanism in sputter deposited Fe–Co–Al thin film

To create a high-density data storage system, a thorough understanding of magnetic domain interactions is essential. In this work, we present a systematic study of magnetic domain state interaction and switching mechanism of Fe–Co–Al films across various thicknesses. Structural analysis confirms the formation of an A2-type disorder structure. Magnetic investigation reveals that all films are soft magnetic in nature, exhibiting a predominant in-plane magnetic anisotropy with a low coercive field that increases from 1.9 mT to 3 mT as the film thickness grows from 5 nm to 25 nm. Analysis of first-order reversal curves reveals the formation of multi-domain (MD) states. An enhancement of magnetic domain interactions occurs as the contour graph shifts along the coercive field direction with an increase in film thickness. Switching field distribution (SFD) analysis reveals broader SFD curves, indicating more inter-grain interactions as magnetostatic interactions between magnetic grains intensify with thickness. Further, magnetic force microscopy analysis confirms the presence of MD structures in all films. Magnetization reversal dynamics elucidates domain wall pinning near to zero field and possesses a large out-of-plane switching field. Simulations are performed to corroborate experimental findings. These findings underscore the critical role of domain state configuration and switching mechanisms for designing spintronic devices using soft magnetic thin films.

Microstructural, dielectric, electrical, electromagnetic, and magnetic property enhancements in GdIG /TrIG/ Mn0.2Co0.3Zn0.5Fe2O4 ferrites composites for electronic devices application

Gadolinium garnet ferrite (GdIG) and terbium garnet ferrite (TrIG), known for their favourable magnetic and dielectric characteristics, were combined with doped zinc spinel ferrite (GdIG)x-(TrIG)y/Mn0.2Co0.3Zn0.5Fe2O4(1-x-y) (at x=1 y=0, x=0 y=1, x=y=0.5, x=y=0.25, x=y=0) to achieve improved permittivity, permeability and magnetic properties with reduced magneto-dielectric losses. Our study details the synthesis process and the resulting enhancements in structural, magnetic, and dielectric properties of the prepared samples. Analysis of the X-ray diffraction (XRD) patterns confirmed the presence of a crystalline structure characterized by both cubic spinel and cubic garnet phases in the composites. The microstructures of the composites were analysed with field emission scanning electron microscopy (FESEM), revealing the variation in a grain size from 0.11 μm to 0.96 μm at x =y=0.5. A thorough link between the crystal structure and XRD spectra, transmission electron microscope (TEM), and selected area electron diffraction (SAED) patterns have all been investigated in order to enhance the characterisation of the samples. At 1KHz, the composites exhibit highest electrical resistivity values of 5.9×106 Ωm and 2.6×106 Ωm. With the incorporation of spinel ferrites in garnet ferrite composite (x=y=0.25) the highest value of dielectric constant (885.2) and low value of dielectric loss (0.07) at 100 KHz has been obtained. Permeability values, derived from permittivity data, showed an increase in real permeability values of from 1.4×1012 to 9.2×1017 for x=y=0.5 to x=y=0.25 composite. Vibrating sample magnetometer (VSM) further confirm that the composite x=y=0.25 has highest magnetic saturation (148.8 emu/g), coercivity (502 Oe) and microwave operating frequency (33.6 GHz). The observed high dielectric constant, low loss values, switching field distribution and good magnetic properties suggest the potential suitability of these samples for various electronic devices like: high frequency devices, antennas, switching devices and magnetic recording devices.

Exploring the effect of exchange coupling in (SrFe9.8Al2La0.2O19)1-x/(Co0.7Zn0.3Fe2O4)x nanocomposites synthesised by sol–gel auto combustion method

Extensive research has been conducted over the last decade to develop permanent magnets utilizing less rare earth materials. Exchange-coupled nanocomposite magnets are a fascinating development in the field of permanent magnets. They involve the combination of hard and soft ferrites, resulting in a unique and evolving magnet. Here we present an in-depth structural, morphological and magnetic characterization of ferrite-based nanostructures obtained through a bottom-up sol−gel approach. The combination of high coercivity of a hard phase SrFe9.8Al2La0.2O19 (SFALO) and high saturation magnetization of a soft phase, Co0.7Zn0.3Fe2O4 (CZFO), allowed us to develop exchange-coupled bi-magnetic nanocomposites by varying the mass percentage (x = 0, 0.1, 0.2, 0.3, 0.4, 1). Thermogravimetric analysis (TGA) up to 1200 °C was used to investigate the material’s thermal properties with the phase formation temperature. Detailed atomic/nano-scale structural characterizations of these nanocomposites were performed by X-ray diffraction and Transmission Electron Microscopy. The average particle size was calculated from the SEM analysis and it was observed that most of the composites with ratio x = 0.1, 0.3 & 0.4 was 145 nm and x = 0.2 was 165 nm. The Switching Field Distribution (SFD) curve revealed the exchange coupling between soft and hard magnetic particles. The findings indicate that the inclusion of a soft magnetic phase has a considerable impact on the exchange coupling between the hard and soft ferrite phases. As the spinel concentration increased, in the composite the saturation magnetization increased from 18 emu/g to 48 emu/g. From the stroner-wholfrathmodel, the decrease in the remanence ratio below 0.5 concludes the crystallites are randomly oriented. The nanocomposite with the ratio x = 0.1 was observed with the high magneto crystalline anisotropy of 2183.23 × 102 (J/m3) and a high energy product (BH)max of 5.5 kJ/m3. The aforementioned features of nanocomposites demonstrate their potential for use in permanent magnet applications.

Unveiling the structural, optical, electrical, and ferromagnetic properties of Ca2+ doped mixed spinel ferrites for switching field high-frequency device applications

In this paper, the calcium-doped nickel-zinc nano-ferrites [Ni0.5Zn0.5CaxFe2-xO4; x = 0.00, 0.10, and 0.30] were prepared using the chemical co-precipitation synthesis route and studied for switching field high-frequency device applications. The structural analysis has been completed by analyzing X-ray diffraction (XRD) patterns. The Rietveld refined XRD patterns confirmed the formation of cubic spinel structure of Ca2+ substituted nickel-zinc ferrites. The detection of metal-oxygen bonds present at A and B lattice sites has been unveiled by Fourier transform infrared (FTIR) spectroscopy. The morphological studies obtained through FESEM (Field emission scanning electron microscopy) analysis showed a reduction in the particle size from 70 nm to 53 nm when the concentration of Ca2+ ions in Ni-Zn ferrites was increased. Energy dispersive spectra (EDS) confirmed the presence of elements present in the prepared composition. The structure of a cubic spinel-shaped unit cell has been verified from three active prominent Raman modes (A1g, A2g, and T2g). Diffuse-reflectance spectroscopy (DRS) exhibits the increment in the bandgap values (from 1.55 eV to 1.63 eV) which helps fabricate highly efficient photovoltaic devices. The ferroelectric measurements yielded a rise in polarization values from 1.461 μC/cm2 to 18.228 μC/cm2 for 10 % Ca2+ ion substitution. The tangent loss values declined from 24 to 3 in Ni-Zn ferrites upon substituting Ca2+ ions. The Vibrating sample Magnetometer (VSM) technique found the increment in the saturation magnetization (Ms) values from 34.724 emu/g to 54.662 emu/g on substituting up to 30 % Ca2+ ions in Ni-Zn ferrites. These obtained results support the material in switching field distribution for high-frequency applications. The results exhibited that the prepared samples can be applicable for switching devices, filters, and microwave absorption devices. The results revealed the maximum frequency between 12 and 18 GHz which is useful for Ku band absorption.

Effect of Shape and Size on Synthesized Triple (Co/Ni/Zn)-Doped α-Fe2O3 Nanoparticles on their Photocatalytic and Scavenging Properties

Co/Ni/Zn triple doped [Formula: see text]-Fe2O3 nanoparticles (NPs) have been synthesized via polyvinylpyrrolidone (PVP)/Azadirachta indica (A. Indica) leaf extract coating. XRD, UV–Vis, SEM, TEM, EDS, Raman spectroscopy, FTIR, VSM were used to characterize the synthesized NPs. XRD pattern revealed that the crystallite size of NPs ranges from 14[Formula: see text]nm to 21[Formula: see text]nm. Spherical NPs were found by SEM/TEM examination ranging from 16[Formula: see text]nm to 26[Formula: see text]nm of doped [Formula: see text]-Fe2O3 NPs. Analysis of the magnetic properties of [Formula: see text]-Fe2O3 NPs revealed antiferromagnetic characteristics, convergence between magnetization curves (MS), and switching field distribution dM/dh below an irreversible temperature of [Formula: see text][Formula: see text]K. Produced catalyst was used for the degradation of anionic azo dye Malachite green (MG) and Rhodamine blue (RhB) dyes under the influence of UV radiation. RhB and MG were reduced as a result of the doped [Formula: see text]-Fe2O3 catalyzing the conversion of dissolved O2 to hydroxyl radicals (OH) when exposed to visible light. This shows that the main active radical specifically engaged in the photo-catalytic breakdown of dyes is OH. The most effective photo-catalyst was determined by investigating the proposed doped [Formula: see text]-Fe2O3 NPs reusability over three cycles. The catalyst was retrieved and utilized three times after the reaction without suffering a substantial loss of catalytic activity. The plant-mediated [Formula: see text]-Fe2O3 NPs have significant antioxidant activity due to their higher phenolic content. These have a promising future with potential applications in health, aging, food preservation, cosmetics, agriculture and environmental protection.

Structure, magnetic, and electrodynamic properties of SrInxFe12‐xO4/Ni0.5Zn0.5Fe2O4 composites at low temperature

AbstractExchange‐coupled hard–soft bi‐magnetic ferrites can be used as isolators, microwave absorption materials, filters, hyperthermia materials, and biosensors with improved energy properties. The nanocomposites with the chemical composition SrInxFe12‐xO4/Ni0.5Zn05Fe2O4 (where x varies from 0.00 to 0.04) have the advantages of both materials: spinel and hexaferrite. The combination of Sr‐hexaferrate with spinel ferrite results in proximity effects, reversal of magnetization in two stages, and blocking temperatures that can be tuned in bi‐magnetic hard and soft ferrites. It was found an anomalius kink in the hysteresis loops and two peaks in the switching field distribution at x ≤ 0.02. The exchange interaction on the surfaces of hard and soft nanoparticles explains the behavior of the magnetic characteristics.

Study of the Switching Field Distribution and the S* Loop Squareness for Evaporated Fe Thin Films: Effect of Substrates and Thickness

Study of the Switching Field Distribution and the S* Loop Squareness for Evaporated Fe Thin Films: Effect of Substrates and Thickness

Bistable magnetic nanowires: A new approach to non-volatile memory with single readout and automatic deletion

A novel approach for a non-volatile destructive readout memory application using bistable magnetic nanowire arrays is presented. The encoded information is stored as binary 1 and 0 by groups of NWs magnetized in the positive and negative states, respectively. We leverage the naturally occurring switching field distribution of the NW array and a tailored alternating decreasing magnetic field to program remanent magnetic states. To retrieve the information, the measured remagnetization curve exhibits a star-like behavior with jumps and plateaus and its derivative converts this information to a binary-type format. Two encoding and readout schemes are proposed and validated: binary bits and barcodes. For each case, the implementation and optimization procedures are illustrated, along with the required processing to obtain a useful readout signal. This strategy holds potential for non-volatile memory applications in which the stored information is erased during reading and can be reused indefinitely.Graphical abstract

Insights into dynamic switching behavior and electric field distribution of depletion-mode GaN HEMT with bonding pad over active layout

Bonding pad over active (BPOA) layout, which stacks traditional horizontal structure pad electrodes vertically above the active area, is an area-effective device architecture and packaging-enabled solution for GaN-based high electron mobility transistors (HEMTs). In this work, the dynamic switching and electric field distribution of such layout, as well as associated capacitance–voltage and trapping characteristics, are comprehensively studied on D-mode GaN-on-sapphire HEMT by performing numerical simulations. In terms of different pad electrodes covering the active area, BPOA is composed of various structures such as gate-related and drain-related BPOAs (i.e. G-BPOA and D-BPOA), among which G-BPOA exhibits inferior switching characteristics due to the additional introduction of Miller capacitance that prolongs the device switching, while breakdown voltage of D-BPOA is 400–900 V lower than other BPOA counterparts due to the interplay between D-BPOA and the drain electrode. Furthermore, the effects of trap capture cross section and trap density on switching characteristics are evaluated. These results highlight the differences in electrical characteristics of various structures within the BPOA layout, and provide valuable insights into BPOA device design and performance improvement.

Tuning the magnetic properties of hard–soft Ba0.5Sr0.5Fe10Al2O19 and Ni0.1Co0.9Fe2O4 nanocomposites via one pot sol–gel auto combustion method for permanent magnet applications

Permanent magnets generate magnetic fields that can be sustained when a reverse field is supplied. These permanent magnets are effective in a wide range of applications. However, strategic rare-earth element demand has increased interest in replacing them with huge energy product (BH)max. Exchange-coupled hard/soft ferrite nanocomposites have the potential to replace a portion of extravagant rare earth element-based magnets. In the present, we have reported the facile auto combustion synthesis of exchange-coupled Ba0.5Sr0.5Fe10Al2O19 and Ni0.1Co0.9Fe2O4 nanocomposites by increasing the content of soft ferrite over the hard from x = 0.1 to 0.4 wt%. The XRD combined with Rietveld analysis reflected the presence of hexaferrite and spinel ferrite without the existence of secondary phases. The absorption bands from the Fourier transform infrared spectrum analysis proved the presence of M–O bonds in tetrahedral sites and octahedral sites. Rod and non-spherical images from TEM represent the hexaferrite and spinel ferrite. The smooth M–H curve and a single peak of the switching field distribution curve prove that the material has undergone a good exchange coupling. The nanopowders displayed an increase in saturation magnetization and a decrease in coercivity with the increases in the spinel content. The prepared nanocomposites were showing higher energy products. The composite with the ratio x = 0.2 displayed a higher value of (BH)max of 13.16 kJ m−3.

The synthesis of CoAl0.3Fe1.7O4/SmFeO3 nanocomposites with enhanced properties for technological applications

The main challenge of the current study is to produce nanocomposites (NCs) of (1-x) CoAl0.3Fe1.7O4 /(x)SmFeO3 with improved structural and magnetic properties using the citrate auto-combustion technique. High-resolution transmission electron microscopy images showed nanostructures with average particle sizes of 32.5 and 52.5 nm for SmFO3 and CoAl0.3Fe1.7O4, respectively. The anisotropy constant values for x = 0.3 are nearly 11 times greater than SmFeO3. The ratio of SmFeO3 incorporated into NCs adjusts their switching field distribution (SFD), making NCs with a low SFD recommended for recording applications. NCs offer the combined advantages of the two constituent phases and can be used to create new and more advanced applications. Based on the estimated data, the prepared NCs can operate at a frequency between 0.1 and 11.9 GHz, making them suitable for developing nanotechnology devices from radio waves traveling through the S-band to the Ku band.Graphical abstract

Structural and magnetic properties of hexagonal ferrite composites with planar and perpendicular anisotropy

In the present work, composites of (x)SrFe12O19(SrM)/(1-x) Ba2Co2Fe12O22(Co2Y) [where x = 0.1, 0.2, 0.3, 0.4] were prepared by physical mixing method. The effect of exchange coupling between SrM and Co2Y phases on composites structural, morphological, and magnetic properties has been investigated. XRD patterns confirmed the co-existence of SrM and Co2Y phases with the presence of a secondary Co2Z phase. Smooth hysteresis loops without kink confirmed that SrM and Co2Y phases in composites are exchange-coupled and signify cooperative magnetic switching among M and Y phase spins. A linear increase in magnetization was observed with an increase in M-phase. On the other hand, a decrease in coercivity was observed due to strong intervening coupling between the phases. A single peak in the switching field distribution curve (SFD) of composites also confirm strong coupling between M and Y phases.

Thermodynamic properties and switching dynamics of perpendicular shape anisotropy MRAM

The power consumption of modern random access memory (RAM) has been a motivation for the development of low-power non-volatile magnetic RAM (MRAM). Based on a CoFeB/MgO magnetic tunnel junction, MRAM must satisfy high thermal stability and a low writing current while being scaled down to a sub-20 nm size to compete with the densities of current RAM technology. A recent development has been to exploit perpendicular shape anisotropy along the easy axis by creating tower structures, with the free layers’ thickness (along the easy axis) being larger than its width. Here we use an atomistic model to explore the temperature dependent properties of thin cylindrical MRAM towers of 5 nm diameter while scaling down the free layer from 48 to 8 nm thick. We find thermal fluctuations are a significant driving force for the switching mechanism at operational temperatures by analysing the switching field distribution from hysteresis data. We find that a reduction of the free layer thickness below 18 nm rapidly loses shape anisotropy, and consequently stability, even at 0 K. Additionally, there is a change in the switching mechanism as the free layer is reduced to 8 nm. Coherent rotation is observed for the 8 nm free layer, while all taller towers demonstrate incoherent rotation via a propagated domain wall.

Tunable and wideband high-performance rare earth-doped Ni-Mg-Cu-Zn nano ferrite-based meta-absorbers for C-band application

Due to advanced technology, electromagnet interference and dissipation problems in the electronic and portable devices at GHz range are increasing daily. Magnetic absorbing materials with outstanding electromagnetic properties, wide bandwidth, and strong absorption are highly desirable. The present investigation deals with the preparation of Ni-Mg-Cu-Zn (NMCZ) substituted nano ferrites with composition of Ni0.3Mg0.2Cu0.3Zn0.2X0.02Fe1.98O4 (X = Nd, Ho, Pr, Gd, Yb). X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), a vibratory sample magnetometer (VSM), and a Vector network analyzer (VNA) were used to investigate these rare earth-doped nanocrystalline ferrites' features. XRD reveals the single spinel phase structure in all Ni-Mg-Cu-Zn ferrites. FTIR spectroscopy shows the presence of tetrahedral and octahedral bands of spinel ferrites. FESEM images reveal the lowest agglomeration for the Ho-doped NMCZ nano-spinel ferrites sample. TEM images show the hexagon shapes of the Yb- and Nd-doped NMCZ ferrites. Pr-doped NMCZ ferrites show more coercivity than other rare earth metals substituted NMCZ nanocrystalline ferrites. VSM analysis was used to calculate the magnetic features like initial permeability, magnetic anisotropy constant, remanence, coercivity, and magnetic moment. High-frequency switching field distributions (SFD) analyses were also investigated. Magnetodielectric characteristics such as losses, permittivity, modulus, Q, ac conductivity, and impedance of the Nd-, Ho-, Pr-, Gd-, Yb-doped Ni-Mg-Cu-Zn ferrites were evaluated. The minimum reflection loss (–57.3 dB) is found at 1.4 GHz for Pr-doped Ni-Mg-Cu-Zn ferrite absorber. However, the reflection loss (RL) of –53.9 dB at 2.9 GHz is observed for Ho-doped Ni-Mg-Cu-Zn ferrite absorber. Soft magnetization, low coercivity, outstanding magnetodielectric, and absorption properties of the Nd-, Ho-, Pr-, Gd- and Yb-doped Ni-Mg-Cu-Zn ferrites are suitable candidates for absorption in telecommunication, defense, and technological industries.

Distributions of easy axes and reversal processes in patterned MRAM arrays

The distribution of the easy-axes in an array of MRAM cells is a vital parameter to understand the switching and characteristics of the devices. By measuring the coercivity as a function of applied-field angle, and remaining close to the perpendicular orientation, a classic Stoner-Wohlfarth approximation has been applied to the resulting variation to determine the standard deviation, sigma , of a Gaussian distribution of the orientation of the easy-magnetisation directions. In this work we have compared MRAM arrays with nominal cells sizes of 20 nm and 60 nm and a range of free layer thicknesses. We have found that a smaller diameter cell will have a wider switching-field distribution with a standard deviation sigma = {9.5}^{circ }. The MRAM arrays consist of pillars produced by etching a multilayer thin film. This value of sigma is dominated by pillar uniformity and edge effects controlling the reversal, reinforcing the need for ever-improving etch processes. This is compared to larger pillars, with distributions as low as sigma = {5.5}^{circ }. Furthermore we found that the distribution broadens from sigma = {5.5}^{circ } to sigma = {8.5}^{circ } with free layer thickness in larger pillars and that thinner films had a more uniform easy-axis orientation. For the 20 nm pillars the non-uniform size distribution of the pillars, with a large and unknown error in the free-layer volume, was highlighted as it was found that the activation volume for the reversal of the free layer 930 nm^3 was larger than the nominal physical volume of the free layer. However for the 60 nm pillars, the activation volume was measured to be equal to one fifth of their physical volume. This implies that the smaller pillars effectively reverse as one entity while the larger pillars reverse via an incoherent mechanism of nucleation and propagation.

Structural and magnetic investigation of novel oxide/ferrite (1-x)MgFe 2O4/(x)Mn1.95Sn0.05O3 nanocomposites

Oxide/ferrite nanocomposites are gaining great attention due to the induced exchange interactions between the different phases. Herein, the weak ferromagnetic MgFe2O4 nano-ferrites are combined with antiferromagnetic Mn1.95Sn0.05O3 nano-oxides, via co-precipitation and ball milling. The synthesized samples demonstrated the combination of ferrite and oxide phases, as confirmed by XRD analysis. This combination also generated two distinct morphologies and particle size distributions, as seen in TEM images. The SAED images depicted the polycrystalline nature of the samples. The XPS technique detected the spin-orbit doublets of the main spectral lines, revealing their different oxidation states. FTIR assisted the merged phases by the presence of multiple vibrational bands. The nanocomposites exhibited weak ferromagnetic nature, emerging from the uncompensated surface spins, as seen in M − H loops. Besides, the switching field distribution curves indicated the exchange coupling between the two phases. EPR spectra showed a decrease in g values as Mn1.95Sn0.05O3 content increased.

Highly efficient lead removal from water by Nd0.90Ho0.10FeO3 nanoparticles and studying their optical and magnetic properties

Ho-doped NdFeO3 was synthesized using the citrate method. The X-ray diffraction (XRD) illustrated that Nd0.90Ho0.10FeO3 was crystalline at the nanoscale, with a crystallite size of 39.136 nm. The field emission scanning electron microscope (FESEM) illustrated the porous nature of Nd0.90Ho0.10FeO3, which increases the active sites to absorb the heavy metals on the sample surface. Energy-dispersive X-ray (EDX) data assures the prepared sample has the chemical formula Nd0.90Ho0.10FeO3. The magnetic properties of Nd0.90Ho0.10FeO3 were determined using the magnetization hysteresis loop and Faraday’s method. Many magnetic parameters of the sample have been discussed, such as the coercive field, the exchange bias (Hex), and the switching field distribution (SFD). Ho-doped NdFeO3 has an antiferromagnetic (AFM) character with an effective magnetic moment of 3.903 B.M. The UV–visible light absorbance of Nd0.90Ho0.10FeO3 is due to the transfer of electrons from the oxygen 2p state to the iron 3d state. Nd0.90Ho0.10FeO3 nanoparticles have an optical direct transition with an energy gap Eg = 1.106 eV. Ho-doped NdFeO3 can adsorb many heavy metals (Co2+, Ni2+, Pb2+, Cr6+, and Cd2+) from water. The removal efficiency is high for Pb2+ ions, which equals 72.39%. The Langmuir isotherm mode is the best-fit model for adsorbing the Pb2+ ions from water.

Annealing temperature effect on structural, mechanical, and magnetic properties of Cd0.40M0.60ZnO2 (M = Mn, Ni) nanocomposites

We report here the effect of annealing temperature Tann (200–600 °C) on the structural, mechanical, and magnetic properties of Cd0.40M0.60ZnO2 (M = Mn, Ni) nanocomposites. The increase in Tann correlates with a significant change in unit cell volume (V), porosity (PS) crystallite size (Dhkl), particle size (r), Debye temperature (θD) and elastic modulus (Y). The values of V, r, θD and Y are higher for the Mn-series than Ni. While the values of PS and Dhkl are higher for Mn than Ni at Tann ≤ 300 °C, and the reverse is true at Tann ≥ 400 °C. The average particle size is 10.6 ± 2.4 nm for Mn-series, but it is decreased to 7.5 ± 4.0 nm for Ni-series, indicating quantum-dot size. Surprisingly, both series exhibit ferromagnetic behavior as Tann increases to 600 °C, but the magnetization parameters for the Mn series are higher than those for Ni. Furthermore, the anisotropy field (Ha) is about 350 times higher than the corrective field (Hc), indicating hard magnetic materials. The switching field distribution (SFD) is increased by annealing, but it is higher for Ni-series than Mn. The considered nanocomposites would be useful for altering plastic deformation and spintronic devices.

Temperature evolution of pseudo magnetic properties and vortex state in Fe71Ga29 thin films

We report on the temperature evolution of pseudo magnetic properties and vortex state in Fe71Ga29 thin films at different substrate temperatures (RT-25 °C, 50 °C, 75 °C, and 150 °C) using minor loop analysis and first-order reversal curves respectively. Phase purity of Fe71Ga29 thin films confirmed with grazing incidence X–ray diffraction, which confirms the A2-type disordered phase. The minor loop parameters such as energy loss coefficient WF0 (362 kOe.emu/cc to 278 kOe.emu/cc) and trough depth coefficient WR0 (67.30 kOe.emu/cc to 50.23 kOe.emu/cc) values drop as grain size increases due to a reduction in defects as a result of an increase in substrate temperature. First-order reversal curves allow us to estimate the coercivity variation and switching field distribution that allow us to get information about magnetic interactions between the domains. Additionally, the contour plots of FORC and MFM phase images infer the coexistence of multidomain and Vortex State (VS) in all the Fe71Ga29 thin films deposited at different substrate temperatures.