Ferromagnetic Behavior Research Articles

Investigation of electrical, dielectric and multiferroic properties of 0.7Bi0.95Sm0.05Fe1-xGaxO3-0.3BaTiO3 composite ceramic system for high temperature piezoelectric applications

Lead-free composite ceramics, 0.7Bi0.95Sm0.05Fe1-xGaxO3-0.3BaTiO3 (BSFGx-BT), were made using a solid-state reaction method for x = 2.5, 5, 10, 15, and 20 %. We have investigated the effects of Samarium (Sm) and Gallium (Ga) co-doping on the crystal structure, topography, spectroscopy, electrical and multiferroic characteristics of the 0.7BiFeO3-0.3BaTiO3 (0.7BFO-0.3BTO) system for piezoelectric applications. The structural results indicate that the composite ceramics exhibited rhombohedra R and tetragonal T phases characterized by R3c and P4mm space groups, respectively which was also further confirmed by X-ray Rietveld refinement pattern analysis. In dielectric behaviour study high Curie temperature of 550 °C was obtained with high temperature stability. Furthermore, the study investigated the effects of grain and grain boundaries on capacitive and resistive properties. The ceramics displayed the characteristics of the negative temperature coefficient of resistance (NTCR). It was observed that as the Ga concentration increased, the grain resistance (Rb) also increased, reaching its maximum value for x =10 %. Additionally, at higher temperatures, this composite exhibited lower electrical resistivity. Importantly, the ceramics showed the co-existence of ferromagnetic and ferroelectric behaviour with the enhanced values of remanent magnetization (Mr)= 0.043 emu/g, coercivity (Hc) = 5730 Oe and remanent polarization (Pr) = 6.07 µC/cm2, coercive field (Ec) = 6.78 kV/cm for the composition x =10 %. These findings suggest that Sm & Ga incorporated 0.7BFO-0.3BTO composite ceramics can show promising high-temperature piezoelectric applications.

Impact of Gd doping on structural and magnetic characteristics of SrFeO3 perovskite nanomaterial

The SrFeO3nanoparticles doped with 5% and 10% Gd were synthesized using the solution combustion method. The phase formation of the synthesized nanoparticles was confirmed by powder x-ray diffraction analysis. Field emission scanning electron microscope and HRTEM were employed to examine the morphology of the samples, revealing well-ordered, agglomerated nanoparticles. Energy dispersive x-ray spectroscopy analysis was conducted on all samples, confirming the presence of the desired elements. X-ray photoelectron spectroscopy confirmed the presence of mixed oxidation states of Fe3+and Fe4+. Magnetization studies, performed using a SQUID magnetometer, showed ferromagnetic behaviour in all samples, with a significant increase in magnetic moment observed with higher Gd doping. The enhanced magnetic moments and reduced coercivity in Gd-doped SrFeO3suggest that these materials could be suitable for spintronic applications.

Superconducting transition of GdBa2Cu3O7-x/La0.7A0.3MnO3 (A=Sr and Ca) bilayers governed by tunable interlayer structural coupling

Bilayers composed of high-Tc cuprate superconductors (HTS) with manganites have garnered significant attention due to the complex interaction between two layers, leading to competition among various ordering phenomena. When HTS and manganties are interfaced, new functionalities can emerge that are absent in the individual components. Notably, epitaxial strain can alter crystal structures and electronic states, significantly impacting superconductivity in HTS/manganite heterostructures. In this study, we analyze the superconducting and ferromagnetic behaviors of GdBa2Cu3O7-x(GdBCO)/La0.7A0.3MnO3(LAMO, where A=Sr and Ca) bilayers, maintain a constant GdBCO thickness of 500 nm while varying the LAMO thickness from 25 to 100 nm. We focus on the local structural correlations between the two layers. Temperature-dependent EXAFS spectra were systematically measured at the Cu and Mn K-edges to investigate the local atomic structures of both layers across the superconducting transition temperature (Tc). Our spectroscopic measurements reveal distinct conformations of the MnO6 octahedra near Tc, which are absent in single-layer LSMO, indicating structural coupling between the layers. Additionally, our magnetization studies show a strong relationship between the structural coupling, magnetic anisotropy (MA), and the superconducting transition of the GdBCO/LAMO bilayers. The additional distortion of the MnO6 octahedra in the GdBCO/LAMO bilayer, likely stemming from structural coupling, may account for the changes in the superconducting transition associated with magnetic anisotropy. This modification of structural coupling can be controlled by adjusting the LAMO thickness, yet it remains highly dependent on the bond geometry of LAMO. The Mn-O bond in LCMO is stiffer than in LSMO, resulting in a smaller change in structural coupling with varying thickness in LCMO compared to LSMO. The disparity in structural coupling directly impacts the magnetic properties of the LAMO layer and subsequently influences the superconducting property ΔTc. Our findings highlight the significance of structural coupling as a critical factor affecting the superconductivity of GdBCO/LAMO bilayers. Furthermore, this study provide foundational insight for designing various applications, such as magnetic sensors and spintronic devices, by enhancing our understanding of local dynamics at the interface between ferromagnets and superconductors.

Photocatalytic and magnetic properties of nanocrystalline Er/Eu-doped ZnO samples

Augmentation of optical and magnetic properties of ZnO system via mono- and co-doping is an efficient approach to achieve enhanced ferromagnetism and photocatalytic activity. In this scenario, we made an endeavor to prepare the nanocrystalline ZnO, ZnO:Eu, and ZnO:(Eu, Er) samples through a co-precipitation technique. Structural analysis ruled out the effectual substitution of Eu and Er in the ZnO lattice without disturbing the original structure. Both ZnO:Eu and ZnO:(Eu, Er) NPs exhibited lower optical band gap values than pure ZnO. In M − H studies at room temperature, ferromagnetic behavior was observed in ZnO, ZnO:Eu, and ZnO:(Eu, Er) NPs. Expectedly, ZnO:(Eu, Er) NPs showed highest H2 evolution than both ZnO and ZnO:Eu NPs beneath solar spectrum. The possible roots behind the extended H2 production are discussed in detail. Hence, ZnO:(Eu, Er) NPs may find in applications is photocatalysis and spintronics.

Influence of local structure and metal-oxygen hybridization on the electrical and magnetic properties of alkaline earth metal (Mg2+, Ca2+, Sr2+) substituted LaFeO3 ceramics

Pristine and alkaline-earth metal-substituted LaFeO3 (La1−xAxFeO3−δ; x = 0 and 0.2; A = Mg2+, Ca2+, and Sr2+) sintered ceramics are prepared from nanoparticles synthesized via a low-temperature citrate sol–gel technique. X-ray diffraction studies confirm the formation of a phase-pure LaFeO3 structure without any secondary phases for all the La1−xAxFeO3−δ compositions. LaFeO3 and La0.8Mg0.2FeO3−δ ceramics show Raman active modes related to La vibration, oxygen octahedral tilting, bending, and stretching. The optical bandgap is estimated to be 2.34 eV for pure LaFeO3 and reduces to 2.23 eV for La0.8Mg0.2FeO3−δ ceramics. On the contrary, La0.8Ca0.2FeO3−δ and La0.8Sr0.2FeO3−δ ceramics show no features in Raman spectra, consistent with the observation of metallic nature and diffuse band edge without any indication of sharp band edge noted. X-ray absorption spectroscopy (XAS) studies on La-L3 and Fe-K-edges confirm the oxidation states of La3+ and Fe3+ in all these ceramics. Local structural distortions and formation of oxygen vacancies in La0.8A0.2FeO3−δ (A = Mg2+, Ca2+, and Sr2+) ceramics are discerned from XAS structure analysis compared to the pristine LaFeO3 ceramics. Magnetic measurements of La1−xAxFeO3−δ reveal weak ferromagnetic nature except for La0.8Mg0.2FeO3−δ, which shows a large magnetization of 4.6 (6.7) emu/g at 300 (5) K. The ferromagnetic behavior of La0.8Mg0.2FeO3−δ ceramics seems to originate from the modification of hybridization between Fe(3d)–O(2p), La(5d)–O(2p), and Fe(4sp)–O(2p) orbitals. An anomalous magnetic transition observed only in zero-field-cooled curves at 88 K in La0.8Ca0.2FeO3−δ and La0.8Sr0.2FeO3−δ ceramics is correlated to the formation of new electronic states containing O 2p character as discerned from pre-peak O-K-edge.

Novel CdFe2O4 nanoparticles facile synthesis and their applications towards practical ammonia detection: an effect of annealing

Cadmium ferrite (CdFe2O4) nanoparticles were synthesized via a simple co-precipitation method, and the effect of annealing temperature over the prepared samples’ structural, morphological, and optical properties was analyzed by varying the temperatures 700, 800, and 900 °C. The x-ray diffraction (XRD) studies revealed that the prepared samples are highly crystalline in nature and belong to a cubic spinel crystal structure, and the crystallite size increases from 32 to 59 nm with respect to the increasing temperature. The surface morphology of the ferrite samples showed the uniformly distributed highly agglomerated particles with larger voids for the ferrite nanoparticles annealed at 900 °C. Optical properties of the prepared CdFe2O4 samples were carried out by diffused reflectance spectroscopy (DRS) and the optical band gap of the samples were found to be 2.57, 2.55 and 2.53 eV. The Vibrating sample magnetometer (VSM) studies at room temperature showcased that the nanoparticle samples possess ferromagnetic behavior, and the magnetization (Ms), Coercivity (Hc), and Retentivity (Mr) values were found to be 27.5 × 10−3 emu g−1, 237.60 Oe, and 1976 × 10−6 emu/g for the CdFe2O4 sample annealed at 900 °C. The gas sensing studies were carried out with the presence of target gas ammonia, and its significant sensing parameters such as gas responsivity (S%), rise time, and recovery times were determined, and these values of CdFe2O4 samples annealed at 900 °C were observed to be 1610%, 7.1 s, and 2.2 s. Our findings strongly suggest that the CdFe2O4 samples annealed at 900 °C hold significant promise as a multifunctional material, particularly in gas-sensing applications. This potential opens an exciting avenue for further research and development.

Emergence of defects-mediated diluted ferromagnetic semiconductor (ZnS: La3+) Quantum Dots: A versatile platform for optoelectronic and spintronic applications

For the first time, La3+ ions incorporated into semiconductor Zinc Sulfide-Quantum Dots (ZnS-QDs), Zn1-xLaxS, were effectively produced via a straightforward co-precipitation approach, with diverse La ratios (0.00 ≤ x ≤ 0.15 at%). The phase analysis of the acquired QDs, conducted through Raman analysis and X-ray diffractometer (XRD), revealed a singular cubic ZnS structure, devoid of any impurities. Morphology studies by HR-TEM showed a nearly spherical particle with a size of approximately 6.4 nm. X-ray photoelectron spectroscope (XPS) investigation disclosed the significant presence of sulfur vacancies, along with the existence of the trivalent oxidation state of lanthanum (La3+) within the ZnS structure. Optical absorbance studies exhibited that all QDs were positioned approximately at the absorption edges of around 270 nm (4.59 eV), surpassing the bulk ZnS energy gap of 337 nm (3.67 eV), harmonically with the quantum confinement effect. Additionally, a pronounced band gap narrowing was observed with increasing the doping level of La ions, on account of the presence of defects that result in the creation of localized states inside the ZnS band structure. The optical results indicated the capability to fine-tune the optical energy gap, dispersion parameters, and enhance the nonlinear optical parameters, which makes these QDs well-suited for use in optoelectronic devices. Furthermore, the photoluminescence (PL) spectra indicated that the La3+-doped ZnS nanocrystals (NCs) exhibited a wide visible emission band (blue emission) at room temperature, influenced by the La-doping concentration. Besides, the La3+-doped ZnS QDs elucidated ferromagnetic behavior at room temperature, which may be accredited to the vacancy-assisted bound magnetic polaron model. Exploring the intriguing magnetic features of ZnS: La3+ QDs could open avenues for developing innovative spintronic devices.

Enhanced magnetism derived from pore-edge spins in thin Fe3GeTe2 nanomeshes

The growth of two-dimensional van der Waals magnetic materials presents attractive opportunities for exploring new physical phenomena and valuable applications. Among these materials, Fe3GeTe2(FGT) exhibits a variety of remarkable properties and has garnered significant attention. Herein, we have for the first time created a nanomesh structure-a honeycomb-like array of hexagonal nanopores-with the zigzag pore-edge atomic structure on thin FGT flakes with and without oxidation of the pore edges. It is revealed that the magnitude of ferromagnetism (FM) significantly increases in both samples compared with bulk flakes without nanomeshes. Critical temperature annealing results in the formation of zigzag pore edges and interpore zigzag-edge nanoribbons. We unveil that the non-oxide (O) termination of the Fe dangling bonds on these zigzag edges enhances FM behavior, while O-termination suppresses this FM by introducing antiferromagnetic behavior through edge O-Fe coupling. FGT nanomeshes hold promise for the creation of strong FM and their effective application in magnetic and spintronic systems.

Paramagnetism found in Mn-doped CuO nanofibers at room temperature explained by XPS , XAS and Rietveld method

CuO and 3 % Mn-doped CuO nanofibers were synthesized employing the electrospinning method. X-ray diffraction (XRD) verified a monoclinic phase with a C 2/c space group. An electronic density analysis, obtained using Fullprof software, was projected on the (110) and (001) planes for both materials, showing modifications in the Cu positions. This fact generated vacancies involved in the paramagnetism formation in the Mn-doped CuO nanofibers, in contrast to the mixed magnetic phase composed by both ferromagnetic and paramagnetic behaviors found in the undoped CuO. The vacancy amount was quantified by X-ray absorption spectroscopy (XAS) applying CASTEP software. In addition, an analysis from Cu 2p XPS peaks supports the predicted Cu-Cu rearrangement by the Fullprof software study, while the presence of Cu1+ confirms the substitution of Mn for Cu in the doped sample.

Green synthesis of NiFe2O4 nanoparticles using Hyphaene thebaica: A facile route towards magnetic and photocatalytic application

Wastewaters from textile industries contribute to significant volumes of colored and hazardous material pollution. Photocatalytic degradation offers a method to reduce organic pollutants, such as dye-containing effluents effectively. Nickel Ferrite (NiFe2O4) receives the most attention in spinel ferrites since it has diverse applications in catalysis, sensor technology, spintronics, magnetocaloric refrigeration, high-density data storage devices, etc. We performed the green synthesis of NiFe2O4 nanoparticles by fruit extract of a gingerbread tree (Hyphaene thebaica). We characterized it with Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), and Raman spectroscopy. The XRD indicates the inverse-spinel structure of the F3dm space group with crystallite size measured as 30 nm. SEM and TEM revealed the spheroidal structure of NiFe2O4 NPs. The green synthesized NiFe2O4 has tetrahedral and octahedral stretching vibrations of Ni–O and Fe–O, as suggested by FTIR. Doublet-like peak behavior in the Raman spectrum indicated the presence of a mixed spinel structure. We studied magnetic behavior in two different modes, and magnetization measurements showed a soft ferromagnetic behavior with a saturation magnetization of 1.527 emu g−1. For photocatalytic potential, the degradation efficiency was 97 % after 90 min at adding 1 g/L of NiFe2O4 nano-catalyst, which shows the high catalytic activity of NiFe2O4 NPs under visible light conditions.

Effect of sintering temperature on magnetic, catalytic and photocatalytic properties of Cu-Co-Mn ferrite catalyst

Wastewater pollution is a pressing environmental issue, necessitating effective remediation strategies to mitigate its impact. This study investigates the use of an efficient catalyst for degrading nitrophenols by converting them into useful aromatic amines, which are crucial building blocks for many pharma industries, and photodegradation of various dyes in their unitary solution as well as in mixture. The Cu-Co-Mn ferrite was synthesized using the sol-gel process and sintered at different temperatures. Structural analysis using XRD and Rietveld refinement revealed a crystal structure corresponding to the Fd3‾m space group having high purity in all the samples. Additionally, the impact of sintering temperature on the magnetic features of the phases were also studied and the findings suggest that all the phases exhibit ferromagnetic behaviour, which means they can be easily separated from reaction mixtures using an external magnetic field. It was also found that higher sintering temperatures lead to a rise in saturation magnetization and magnetic moment with decrease in coercivity (Hc). Further, it was observed that Curie temperature (Tc) increases with increase in sintering temperature with the exception of CFM400. The catalytic performance of all the catalysts, including CFM400, CFM500, CFM600, CFM800, and CFM1000, was evaluated and the results indicate that CFM400 exhibits the highest catalytic activity for nitrophenols reduction and photodegradation of dyes, which could be accredited to its larger BET surface area and lower PL intensity. Overall, the structural and magnetic features of the catalyst’s sheds light on the underlying mechanisms governing their catalytic activity. These insights offer valuable guidance in the designing and development of effective catalysts for sustainable wastewater treatment practices, emphasizing the importance of considering both structural and magnetic features in catalyst design.

Structural, optical, magnetic, and photocatalytic degradation characteristics of Co0.5Ni0.5Fe2O4 nanoparticles synthesized by plasma arc discharge process

Co0.5Ni0.5Fe2O4 nanoparticles were prepared by the plasma arc discharge method under arc currents of 200, 300, and 400 A in an air atmosphere. The XRD patterns reveal the formation of a single-phase cubic spinel. According to FESEM results, the average particle size in all powders is less than 100 nm. X-ray elemental mapping data confirms the homogeneous composition of the as-synthesized powders. The magnetic and optical data demonstrate a primarily soft ferromagnetic semiconductor behavior, characterized by a saturation magnetization ranging from 62 to 83 emu/g and a band gap energy between 1.86 and 2.15 eV. The photocatalytic activity of the powders synthesized using a 200 A arc, which possesses the lowest band gap energy of 1.86 eV, was assessed by conducting photodegradation experiments on the dyes congo red, methylene blue, and malachite green under UV irradiation in the presence and absence of H2O2. After 105 min of irradiation, the photocatalytic efficiencies of the powders without H2O2 were determined to be 29 %, 57 %, and 83 % for congo red, methylene blue, and malachite green dyes, respectively. However, in the presence of H2O2, the efficiencies significantly increase to 91 %, 95 %, and 96 % for the respective dyes.

Synthesis of Samarium Nitride Thin Films on Magnesium Oxide (001) Substrates Using Molecular Beam Epitaxy

Rare-earth nitrides are an exciting family of materials with a wide variety of properties desirable for new physics and applications in spintronics and superconducting devices. Among them, samarium nitride is an interesting compound reported to have ferromagnetic behavior coupled with the potential existence of p-wave superconductivity. Synthesis of high-quality thin films is essential in order to manifest these behaviors and understand the impact that vacancies, structural distortions, and doping can have on these properties. In this study, we report the synthesis of samarium nitride monocrystalline thin films on magnesium oxide (001) substrates with a chromium nitride capping layer using molecular beam epitaxy (MBE). We observed a high-quality monocrystalline SmN film with matching orientation to the substrate, then optimized the growth temperature. Despite the initial 2 nm of growth showing formation of a potential samarium oxide layer, the subsequent layers showed high-quality SmN, with semiconducting behavior revealed by an increase in resistivity with decreasing temperature. These promising results highlight the importance of studying diverse heteroepitaxial schemes and open the door for integration of rare-earth nitrides and transition metal nitrides for future spintronic devices.

Engineered hybrid iron‐cobalt metal oxide nanoparticles for effective adsorption of malachite green dye

AbstractBACKGROUNDHybrid iron and cobalt metal oxide nanoparticles are well known; however, are not optimized in terms of size and stability. We engineered these hybrid nanoparticles using the co‐precipitation method and characterized them by various techniques, which are then used for the effective adsorption and removal of malachite green (MG) dye.RESULTSThe ideal conditions for synthesis are determined to be 50:50 ratio of Fe2O3 and CoO, pH of 11, temperature range of 40 °C–60 °C, and reactant addition time of 20 min. These hybrid nanoadsorbents effectively eliminated MG dye from aqueous solutions. Factors such as initial MG dye concentration, pH of the medium, contact time, temperature, and nanoadsorbent dose were optimized for the MG removal to achieve a maximum removal efficiency of 96.9%. Non‐linear fitting of data indicates that both Langmuir and Freundlich models provided the best fit, suggesting the presence of both monolayer and multilayer adsorption of MG on hybrid nanoparticles. The kinetics of MG dye removal are better controlled by the intraparticle diffusion (IPD) phenomenon. The adsorption of MG onto the hybrid nanoparticles was confirmed to be endothermic, with negative ΔG and positive ΔH values. The optimized synthetic conditions also positively impacted the hybrid nanoparticles which enhanced the adsorption and exhibited ferromagnetic behavior as compared to the superparamagnetic behavior reported in the literature, making them significantly important for dye removal applications.CONCLUSIONThese findings demonstrate the potential of optimized hybrid nanoparticles as effective nanoadsorbents for dye removal applications, with implications for further applications in photocatalysis and sensing. © 2024 Society of Chemical Industry (SCI).

Magnetic properties and microstructural of ion-implanted Gadolia doped Ceria-Barium monoferrite thin film deposited on Kapton for electromagnetic wave absorber application

Gadolia-doped Ceria-Barium Monoferrite (GDC-BaFe2O4) thin films have been deposited on Kapton sheets using the DC sputtering method as electromagnetic (EM) wave-absorbing materials. The present study has examined the structural, magnetic, and microwave absorption properties of GDC-BaFe2O4. The primary approaches used in this investigation included changing the surface form and applying EM wave-absorbing materials as surface coatings. X-ray diffraction research showed that the GDC-BaFe2O4 thin films have an orthorhombic crystal structure. The bonding investigation revealed the existence of Fe-O, Ce-O, and Ba-O-Ba functional groups at 426.87, 517.42 and 1014.84 cm−1, respectively. Vibrating-sample magnetometry confirmed that saturation magnetization decreased with increasing sputtering time and revealed the ferromagnetic behavior of the GDC-BaFe2O4 thin film. Ce, Gd, Ba, Fe, and O were evenly and similarly distributed over the Kapton surface of the GDC-BaFe2O4 thin films, according to energy-dispersive X-ray spectroscopy and scanning electron microscopy. Based on the atomic force microscopy test, the root-mean-square roughness (Rq) increased during the ion implantation procedure. With a 7.5-minute sputtering period, the microwave absorption ability reached a maximum reflection loss value of −39.6 dB (99.98 %) at 10 GHz. As a result of these findings, GDC-BaFe2O4 appears to be a promising candidate for EM wave absorption.

Harvesting Magneto-Acoustic Waves Using Magnetic 2D Chromium Telluride (CrTe3).

A vast majority of electrical devices have integrated magnetic units, which generate constant magnetic fields with noticeable vibrations. The majority of existing nanogenerators acquire energy through friction/mechanical forces and most of these instances overlook acoustic vibrations and magnetic fields. Magnetic two-dimensional (2D) tellurides present a wide range of possibilities for devising a potential flexible energy harvester. 2D chromium telluride (2D CrTe3) is synthesized, which exhibits ferromagnetic behavior with a higher T c of ≈224 K. The structure exhibits stable high remnant magnetization, making 2D CrTe3 a potential material for harvesting magneto-acoustic waves. A magneto-acoustic nanogenerator (MANG) is fabricated and the basic mechanical stability and sensitivity of the device with change in load conditions are tested. A high surface charge density of 2.919 mC m-2 is obtained for the device. The thermal strain created in the lattice structure is examined using in-situ Raman spectroscopy. The magnetic anisotropy energy (MAE) responsible for long-range FM ordering is calculated by theoretical modelling with insights into opening of electronic bandgap which enhances the flexoelectric effects. The MANG can be a potential NG to synergistically tap into the magneto-acoustic vibrations generated from the frequency changes of a vibrating device such as loudspeakers.

Crossover from Relativistic to Non-Relativistic Net Magnetization for MnTe Altermagnet Candidate

We experimentally study magnetization reversal curves for MnTe single crystals, which is the altermagnetic candidate. Above 85 K temperature, we confirm the antiferromagnetic behavior of magnetization M, which is known for α-MnTe. Below 85 K, we observe anomalous low-field magnetization behavior, which is accompanied by the sophisticated \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$M(\\alpha )$$\\end{document} angle dependence with beating pattern as the interplay between \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$M(\\alpha )$$\\end{document} maxima and minima: in low fields, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$M(\\alpha )$$\\end{document} shows ferromagnetic-like 180° periodicity, while at high magnetic fields, the periodicity is changed to the 90° one. This angle dependence is the most striking result of our experiment, while it can not be expected for standard magnetic systems. In contrast, in altermagnets, symmetry allows ferromagnetic behavior only due to the spin–orbit coupling. Thus, we claim that our experiment shows the effect of weak spin–orbit coupling in MnTe, with crossover from relativistic to non-relativistic net magnetization, and, therefore, we experimentally confirm altermagnetism in MnTe.

Tailoring the optoelectronic and spintronics properties of Cr-doped ZnS nanostructure thin films

This paper discusses the tailoring of the optoelectronic and spintronic of Cr3+-doped ZnS nanostructured electron beam evaporated thin films. The XRD measurements confirm the zinc blende cubic structure for the films with a preferred orientation along the (111) direction. The nanostructured features of the films were verified from the XRD and AFM results. The EDXS and XPS data show the stoichiometric chemical and electronic states of the films. Spectrophotometry measurements for the films show that the energy gap decreases from 3.67 eV to 3.43 eV as the Cr3+ increases from 0 at. % to 8.0 at.%. Such reduction of the Eg of the Cr3+-doped ZnS is attributed to the sp-d coupling. The strong PL asymmetric peak of the Cr3+-doped ZnS is observed, which is quenched and red shifted with increasing Cr doping level. Furthermore, the magnetic measurements show the occurrence of weak room temperature ferromagnetic behavior. On the other hand, the results further show that the magnetization increases with the increase of the Cr3+ dopants up to x = 0.05, then decreases with increasing the Cr doping above x = 0.05. This can be attributed to the development of the antiferromagnetic ordering.

Investigating the dielectric and ferromagnetic behaviour of Ni and Co dual doped ZnO for diluted magnetic semiconductor

Herein, Ni/Co co-doped ZnO nanoparticles (NPs) were successfully prepared via chemical co-precipitation process. The structural, purity and crystallite size of as-prepared particles were confirmed by using x-ray diffraction (XRD). The results revealed the hexagonal wurtzite structure of ZnO without any impurity phase of as-prepared samples. The crystallite size decreased from 34.9 to 9.6 nm, whereas lattice strain reduced to 0.00086. The change in crystallite size, lattice parameters, strains and dislocation density further indicates the successful incorporation of dopants in ZnO host lattice. The dielectric properties, ac conductivity, and magnetic behaviour were steadily examined. The dielectric constant has been found to be 1070 with 5wt% at low frequency and become constant at higher frequency. It was revealed that dopant additions lead to attain high dielectric constant and low loss possibly attributed to interface polarization, and dipole polarization due to oxygen vacancy defects. M-H measurement observed that ferromagnetism at room temperature pure and doped ZnO samples. The ferromagnetic behaviour of pure ZnO NPs with Ms = 0.17 emu g−1, Mr = 0.11 emu g−1 and Hc = 67 which was increased to Ms = 0.85 emu g−1 and Mr = 0.65 emu/g for 5wt% Co. This improvement with increasing Co concentration indicates that oxygen defects may stabilize the ferromagnetic order. These interesting features encouraging to use this material for ultrahigh dielectric materials and spintronics.

Investigating magnetic properties and Curie temperatures of FeX2 (X=S, Se, Te) monolayers

In recent years, there has been a growing interest in two-dimensional magnetic materials. With their unique properties and tunable characteristics, magnetic monolayers hold significant potential for the next-generation devices. This study employs the first principles calculations to examine the electronic, structural, and magnetic properties of the hexagonal and trigonal FeX2 (X=S, Se, Te) monolayers. The calculations show that only two configurations are dynamically stable which are hexagonal FeS2 and FeTe2. Both H-FeS2 and H-FeTe2 monolayers exhibit metallic behavior in PBE calculations. Furthermore, the results indicate that these monolayers also exhibit ferromagnetic behavior. This ferromagnetic ordering suggests significant interactions between the magnetic moments. The magnetic exchange constants are determined by using 2D Ising model. After determining the magnetic exchange constants, a Monte Carlo simulation is performed to obtain the Curie temperature. Furthermore, the influence of the Hubbard U parameter on the electronic and magnetic structure was also examined, revealing significant modifications in the band structure and magnetic moments. Additionally, magnetic exchange constants were calculated for the PBE+U case, as well as using the TB2J method, to provide a comprehensive understanding of the magnetic properties of the stable structures.