Magnetic Characteristics Research Articles

High-latitude Observations of Dissipation-range Turbulence by the Ulysses Spacecraft during the Solar Minimum of 1993–96: The Spectral Break and Anisotropy

We examine Ulysses magnetic field observations from 1993 to 1996 as the spacecraft made its first fast-latitude scan from the southern to the northern hemisphere. Most of the observations we use are representative of high-latitude solar minimum conditions. We examine magnetic field power spectra characteristics of interplanetary turbulence at high frequencies, where the spectrum breaks from an inertial range into the ion dissipation range. The onset and spectral index of the dissipation spectrum are consistent with low-latitude observations at 1 au. Both ranges have a ratio of power in perpendicular magnetic field components to parallel components near 3. The power spectrum ratio test developed by Bieber et al. for single-spacecraft analyses that determines the underlying anisotropy of the wave vectors yields only marginally more energy associated with field-aligned wave vectors than perpendicular wave vectors when comparing the inertial and dissipation-range spectra. The lack of significant change in the anisotropies between the inertial and dissipation ranges contrasts strongly with the turbulence found typically for 1 au near-ecliptic observations, where significant differences in both anisotropies are observed.

Defect classification and quantification method based on AC magnetic flux leakage time domain signal characteristics

Pipelines play a crucial role in industries such as petroleum and nuclear power, where non-destructive testing is essential. Magnetic flux leakage testing methods are widely used for pipeline inspection due to their ability to detect both internal and external defects. However, accurately classifying and evaluating the size of such defects poses challenges due to the complex coupling relationship between ferromagnetic materials and defect magnetic fields. This paper proposes a method for defect classification and quantification based on the time domain characteristics of AC magnetic flux leakage signals. Firstly, the paper explores the shielding effects caused by transient high magnetic permeability within the material on signals from internal defects. It analyzes the differences in signals between internal and external defects. Then, based on the nonlinear attributes of defect signals, the paper proposes a defect classification method based on derivatives analysis of the windowed time-domain signal. Moreover, the study finds that rising time and zero-crossing time can be used to assess the depth of internal and external defects separately, which can decouple the width and depth. Finally, experimental validation confirms the effectiveness of defects classification and quantification. This paper provides a feasible method for evaluating the defect of ferromagnetic materials.

Structural, thermodynamic, magnetic and electronic properties of novel bromide double perovskites Rb2XBr6 (X4+ = V4+, Cr4+, Mn4+) from first-principles DFT computational modeling

The structural, thermodynamic stability, magnetic, and electronic characteristics of rubidium-based bromide double perovskites Rb2XBr6 (X4+ = V4+, Cr4+, Mn4+) have been verified to be explained using density functional theory (DFT) computations. The Perdew-Burke-Ernzerhof functional in generalized gradient approximation (PBE-GGA) is implemented to treat the exchange-correlation. The structural optimization, formation energy, tolerance factor, and thermodynamic demonstrate the reliability and stability of all Rb2XBr6 in face-centered cubic structure (Fm-3m). Spin-polarized band structures and density of states show the presence of half-metallic, semimetallic, and semiconductor nature in Rb2XBr6 materials, respectively. Additionally, we investigated the magnetic moments of Rb2XBr6 and the genesis of ferromagnetic and electronic structures in these systems. It found that Rb2XBr6 possess an integer total magnetic moment of 1.0 μB (X4+ = V4+), 2.0 μB (X4+ = Cr4+), and 3.0 μB (X4+ = Mn4+), where the 3d-orbitals of X4+ contribute the up majority of magnetic moments. The significant electronic and ferromagnetic properties are attributed to the unpaired electrons in V-3d3, Cr-3d5, and Mn-3d5. The PBE-GGA computations reveal that the ferromagnetic Curie temperature of Rb2XBr6 is 204 K, 387 K and 566 K, respectively. The obtained results show that Rb2XBr6 are reliable inorganic materials and candidates for spintronics and optoelectronics technologies.

Imaging Descriptors of Human Papilloma Virus-mediated and Human Papilloma Virus-negative Oropharyngeal Cancers in Indian Subcontinental Patients

Abstract Background: Nearly 24,000 new cases of oropharyngeal cancers (OPCs) are reported per year in India, constituting 3.9% of cancers in all sites. By 2009, Human papilloma virus (HPV), in particular HPV-16, was established as an etiological factor and even a causative agent in OPCs being associated with up to 70% OPCs. Prior imaging-based studies have described certain differentiating factors between HPV-mediated and HPV-negative OPC, highlighting computed tomography and magnetic resonance characteristics that could help differentiate the two groups. Our study aimed to evaluate any imaging differences between HPV-mediated and non-HPV-mediated oropharyngeal malignancies in the Indian subcontinent population. Methods: Seventy-nine patients from the Indian subcontinent who were referred to a tertiary center in southern India between the period of January 2019 to September 2020 (19 months) were included in the study. Imaging descriptors were documented by blinded radiologists, and univariate and multivariate analysis of various imaging descriptors and imaging differences between HPV-mediated and non-HPV cases were attempted to be identified. Results: We found no statistically significant imaging differences between HPV-mediated and non-HPV-mediated oropharyngeal malignancies. The only epidemiologically significant difference in the two groups was that in women and nonsmokers, HPV-mediated malignancies were more common. Conclusion: HPV-mediated and HPV-negative malignancies have similar primary tumor as well as nodal imaging characteristics. Previously cited differences in the two groups, in Western literature, could not be demonstrated in our population. It implores further research into whether downstaging of treatment and better prognosis of HPV-mediated malignancies is actually applicable in the Indian subcontinent setting.

Degradation of Dyes Using Biologically Synthesized Nanoparticles by Aloe barbadensis Leaves Extract

AbstractNanotechnology has enormous, economic, social, and environmental ramifications. Due to their capacity to survive in complex processes, inorganic nanomaterials like metal/metal oxides have received substantial study during the past decade. Nanoparticles have antibacterial, magnetic, electrical, and catalytic characteristics due to their greater surface area. There are several methods to develop nanoparticles but environment friendly behavior with no toxic byproducts attracts researchers toward biological process of nanoparticles. This work synthesizes copper oxide (CuO) nanoparticles and zinc oxide (ZnO) with Aloe barbadensis (Aloe vera) leaves extract and successfully characterizes them with different analytical techniques. The catalytic activity of such nanoparticles tests over different cationic and anionic dyes like methylene blue (MB), methyl orange (MO), and methyl red (MR) for different intervals of time and reveals. The degradation efficiency of CuO nanoparticles for MB, MO, and MR dyes are 59.92%, 73.48%, and 73.10% respectively, and for ZnO nanoparticles it is 81.44%, 76.46%, and 63.30% for MB, MO, and MR dyes respectively under the exposure of sunlight for 8 h. The present work successfully develops an ecofriendly process of dye degradation by biologically synthesized nanoparticles.

Analytical calculation of the kinetic q factor and resonant response of toroidally confined plasmas

Symmetry-breaking perturbations in axisymmetric toroidal plasma configurations have a drastic impact on particle, energy, and momentum transport in fusion devices, thereby affecting their confinement properties. The perturbative modes strongly affect particles with specific kinetic characteristics through resonant mode–particle interactions. In this work, we present an analytical calculation of the kinetic q factor, enabling the identification of particles with kinetic properties that meet the resonant conditions. This allows us to predict the locations and structures of the corresponding resonant island chains, as well as the existence of transport barriers in the particle phase space. The analytical results, derived for the case of a large aspect ratio configuration, are systematically compared to numerical simulations, and their domain of validity is thoroughly investigated and explained. Our findings demonstrate that calculating the kinetic q factor and its dependence on both particle and magnetic field characteristics provides a valuable tool for understanding and predicting the resonant plasma response to non-axisymmetric perturbations. Moreover, this approach can be semi-analytically applied to generic realistic experimental equilibria, offering a low-computational-cost method for scenario investigations under various multi-scale perturbative modes.

Self-triggered MPC with adaptive prediction horizon for nano-satellite attitude control system

Nano-satellites are essential tools for various applications, including scientific experiments, deep space exploration and astronomical observation. Achieving precise model predictions is crucial for their successful operation. To address the intricate constraints of nano-satellites and enhance control performance, the Model Predictive Control (MPC) algorithm is an effective solution. However, implementing an MPC-based attitude control system in actual engineering scenarios presents significant challenges, primarily due to the substantial computational burden, especially given the limited onboard computing resources of nano-satellites. In this paper, we introduce a modified adaptive self-triggered model predictive control (ST-MPC) algorithm designed to stabilize the attitude of nano-satellites, while simultaneously reducing communication and computational overhead compared to traditional MPC methods. The proposed self-triggered mechanism dynamically determines the next trigger time according to the system state. Moreover, we incorporate considerations for the efficiency of actuators to address the constraints imposed by the magnetic torque characteristics within the modified self-triggered mechanism. Additionally, a strategy for adaptive prediction horizon is proposed to balance computation load and control accuracy. The results of our simulations demonstrate the effectiveness of the modified ST-MPC algorithm in comparison to both traditional MPC and standard ST-MPC approaches. This algorithm may have the potential to significantly impact attitude control applications for nano-satellites.

Non-metallic doped GeC monolayer: tuning electronic and photo-electrocatalysis for water splitting.

We conducted a first-principles study on the electronic, magnetic, and optical characteristics of non-metallic atoms (B, C, F, H, N, O, P, S, and Si) doped in single-layer carbon germanium (GeC). The findings indicate that the introduction of various non-metallic atoms into the monolayer GeC leads to modifications in its band structure properties. Different non-metallic atoms doped in single-layer GeC will produce both magnetic and non-magnetic properties. B-, H-, N-, and P-doped GeC systems exhibit magnetic properties, while C-, F-, O-, S-, and Si-doped single-layer GeC systems exhibit non-magnetic properties. Different non-metallic-doped single-layer GeC systems will produce semiconductor, semimetallic, and metallic properties. The C-, N-, O-, P-, S-, and Si-doped GeC systems still exhibit semiconductor properties. The H-doped GeC system exhibits semimetallic properties, while the B- and F-doped GeC systems exhibit metallic properties. Other than that, the doping of B, H, N, and P atoms can modulate the magnetism of single-layer GeC. Subsequently, we studied the influence of the doping behavior on the work function, where the work function of the single-layer GeC system doped with P atoms is very small, indicating that its corresponding doping system (P-doped GeC system) can produce a good field emission effect. In the optical spectrum, the doped systems have a certain influence in the far ultraviolet region. Furthermore, our results showed that S- and Si-doped single-layer GeC systems are conducive to photocatalysis compared to the single-layer GeC system.

Investigation of the structural, electronic, magnetic, and optical properties of the double perovskite oxide semiconductor La2NiMnO6: Ab initio calculations by using GGA-PBE and GGA + mBJ approximations

In this paper, we examined the La2NiMnO6 double perovskite oxide semiconductor materials, our treatment included the structural, electronic, magnetic, and optical characteristics by utilizing the density functional theory, which was performed in the Wien2k software. The exchange–correlation potential was carried out in combination with the GGA-PBE (Perdew Burke Ernzerhof Generalized Gradient Approximation), and GGA + mBJ (modified Becke and Johnson) was used for the exchange–correlation potentials. The results suggest that the compound La2NiMnO6 exhibits in a ferrimagnetic state. It was also found that the stable ground state of the compound is ferrimagnetic. The results demonstrate that La2NiMnO6 has a band gap whose spin-up value is 0 eV and spin-down (dn) value is 2.86 eV (GGA-PBE), with up values is 0 eV and dn value being of 3 eV (GGA + mBJ). We also explored different optical properties, among them electron energy loss, absorption coefficient, real and imaginary dielectric tensor, and real and imaginary optical conductivity.

Waves and Instabilities in Saturn's Magnetosheath: 1 Mirror Mode Waves and Their Impact on Magnetopause Reconnection

AbstractA comprehensive catalog of 1,589 Saturn magnetosheath traversals by Cassini between 2004 and 2012 was used to perform a statistical study of mirror mode (MM) waves and assess their role in influencing magnetic reconnection at the magnetopause (MP). MM waves have been observed in many planetary magnetospheres and magnetosheaths, comets and the solar wind. Understanding the conditions under which they grow and dominate can reveal their role in influencing plasma dynamics. Using a thresholding method on both magnetic field and plasma data, MM wave candidates can be identified. The magnetic field characteristics and occurrence distributions of these waves against different locations and conditions were found. MM waves were found from 4 to 19 hr local time (partly due to data coverage), and distances of 0–12 from the magnetopause (MP). The occurrence of MM dips was more frequent near the MP and magnetosheath flanks, analogous to the Jovian system. MM dips exhibited a minimum field strength saturation 0.5 nT, with the largest dip inferred to be in mirror‐stable plasma. Notably, larger amplitude MM dips were typically found nearer the MP boundary which increases across the boundary thus increasing the magnetic shear necessary for the onset of MP reconnection. Thus, MM waves may be important in plasma dynamics near Saturn's magnetopause.

Focused electron beam induced deposition of magnetic tips for improved magnetic force microscopy

The combination of focused electron beam induced deposition (FEBID) and magnetic force microscopy (MFM) has opened up new possibilities in nanoscale magnetic imaging. FEBID offers precise control over the dimensions and magnetic properties of the MFM probes, enabling the development of high-performance magnetic tips with enhanced capabilities compared to conventional ones. These improved tips offer superior resolution, sensitivity, and versatility in nanoscale magnetic surface characterization. Here, we compare the performance of a commercial MFM tip and a FEBID-grown Fe tip in a Ni80Fe20/NdCo5 film. The FEBID tip exhibited superior lateral resolution for topography imaging, likely due to its sharper and well-defined geometry, with a tip diameter of approximately 20 nm. MFM measurements further confirmed this advantage, revealing better-defined magnetic domains and higher magnetic contrast with the FEBID-functionalized probes compared to the commercial tip. This improvement can be attributed to the possibility to optimize the tip-sample magnetic interaction for the FEBID tip. By reducing the lift height of the second pass, we were able to bring the tip closer to the sample, enhancing the magnetic signal without introducing significant topographic artifacts. Overall, these findings highlight the potential of FEBID for creating high-resolution and high-sensitivity MFM tips.

Structural, magnetic, and magnetocaloric characterizations of geometrically-frustrated SrRE2O4 (RE = Gd, Dy, Ho, Er) oxides for low-temperature cooling applications

The magnetocaloric (MC) properties of many rare earth (RE)-based magnetic solids have been intensively investigated. This research aims to develop suitable MC materials for low-temperature cooling application and to better elucidate their intrinsic properties. We have fabricated four single-phase SrRE2O4 (RE = Gd, Dy, Ho, Er) oxides and conducted a systematic experimental investigation into their structural, magnetic, and low-temperature MC properties. All these SrRE2O4 oxides crystallize in an orthorhombic structure (space group Pnma) and exhibit typical geometrical frustration. This frustration arises from the one-dimensional RE ion zigzag ladders along the c-axis, which link the two-dimensional honeycomb lattice in the ab plane. The elements in SrRE2O4 oxides are uniformly distributed and present with valence states of Sr2+, RE3+, and O2−, respectively. Large low-temperature MC effects and notable performances are realized in these SrRE2O4 oxides, determined by the MC parameters of magnetic entropy change, refrigerant capacity, and temperature-averaged entropy change (with a lift of 5 K). These MC parameters under a magnetic field change of 0–70 kOe are as follows: 34.18 J/kgK, 275.88 J/kg, and 30.74 J/kgK for SrGd2O4; 18.13 J/kgK, 253.83 J/kg, and 17.54 J/kgK for SrDy2O4; 18.81 J/kgK, 354.77 J/kg, and 18.61 J/kgK for SrHo2O4; and 22.63 J/kgK, 284.25 J/kg, and 21.97 J/kgK for SrEr2O4. These values are comparable to those of most recently updated low-temperature MC materials with remarkable performances, making these SrRE2O4 oxides highly interesting for practical cooling applications.

Exploration of Rayleigh loop vis-to-vis high applied magnetic field hysteresis loops phenomena in barium hexaferrite-Copper ferrite ferrimagnetic composites

Recent research interest has surged in magnetic composite materials, driven by the increasing demand for permanent magnets, magnetic fluids, and magnetic sensors, in various technological applications. Among all these materials, the 1BaFe12O19 + (x) CuFe2O4 composites have developed as particularly promising in terms of its magnetic properties. However, despite its potential, detailed insights into the magnetic characteristics of this composite remain scarce in the existing literature. In this article, we address this gap by thoroughly investigating the magnetic properties of the 1BaFe12O19 + (x) CuFe2O4 composite across a range of compositions (x = 1 to 6). This present study focused on both low and high applied magnetic fields, examining the material’s behavior in Rayleigh region as well as under intense magnetic influences. At low magnetic fields, the M−H loop exhibits distinctive elliptical or lens shape. Notably, the susceptibility (χm) initially increases but then declines after reaching a critical threshold with increasing magnetic field strength. The analysis of different magnetic parameters, including maximum magnetization (Mm), remanent magnetization (Mr), coercive field (Hc), and the ratio of remanent to maximum magnetization (Mr/Mm), derived from the M−H loops across different applied magnetic fields have been reported here. According to present research, these magnetic parameters show a growing trendency with increasing applied magnetic field strength until they get close to saturation. Results are correlated with the magnetic domain wall dynamics.

Synthesis, crystallographic, spectroscopic, magnetic, and DFT characterization of a new strandberg-type polyoxometalate: (H2AEP)4[CoP2Mo5]2 ̶ first principles calculations

This work reports the synthesis of a novel diphosphopentamolybdate compound with the formula (C6H17N3)4[Co(H2O)4P2Mo5O23]2‧8·74H2O abbreviated as (H2AEP)4[CoP2Mo5]2. Characterization of this compound was carried out using various techniques, including X-ray diffraction, thermal analysis (TGA), and spectroscopies such as FT-IR, Raman, UV–visible, and fluorescence. The structural study reveals that the studied material crystallizes in the orthorhombic system Pca21 with lattice parameters of a = 18.6348(16) Å, b = 11.8613(10) Å, c = 35.074(3) Å, and volume V = 7752.5(11) Å3, and a number of formula units per primitive cell Z = 4. The crystal structure study reveals that the Strandberg anions (P2Mo5O23)6− are connected to Co(II) octahedra through the terminal oxygen atoms of the PO4 tetrahedra, creating 1-D anionic chains in the crystallographic direction [101]. The 1-(2-Aminoethyl)piperazinium (AEP) cations are located within the anionic framework to neutralize its negative charge. The magnetic characteristics of the compound were investigated by examining the temperature-dependent molecular susceptibility over the range of 2–300 K. The analysis revealed the presence of an antiferromagnetic exchange interaction. Moreover, the material's refractive index exhibited significant dispersive behavior within the visible spectrum, indicating its potential for use in visible optical communication devices. A first-principles density functional theory (DFT)-based computational study confirms the semiconducting behavior of (H2AEP)4[CoP2Mo5]2, revealing that in the ground state, high-spin octahedrally coordinated Co2+ cations exhibit a very weak antiferromagnetic coupling along the [Co(H2O)4P2Mo5O23]∞4−chains running in the crystal a direction.

The magnetic characteristics of spinel-type MnCo2O4 at low temperatures

We report the magnetic properties of spinel oxide MnCo2O4 at low temperatures which is prepared through the sol-gel reaction process. The XPS results suggest that Mn3+ atoms exist in the octahedral sublattice originally occupied by Co3+ atoms. Afterwards, the AC susceptibility was measured at various frequencies, confirming a spin glass behavior at low temperatures. Additionally, analysis of the hysteresis loops revealed the presence of the exchange bias effect in our sample. The coexistence of spin glass behavior and the exchange bias effect in MnCo2O4 is attributed to the competition between ferromagnetic and antiferromagnetic interaction. The disorders of magnetic atoms in the lattice will also provide synergy for these magnetic behaviors.

Mechanochemically assisted synthesis, inversion degree and magnetization of spinel compounds across the (Zn,Mg)Fe2O4 system for flexible smart devices

Magnetic spinel oxides are multifunctional materials used or under consideration for a range of applications across electronics, communication technologies, remediation and health. They can also present high magnetostriction coefficients, and are being investigated as active inorganic fillers in polymer matrix composites for flexible sensors and actuators. However, state-of-the-art materials for these later applications are NiFe2O4- and CoFe2O4-based compositions, and it is necessary to find environmentally-friendly alternatives free of toxic elements that provide comparable responses, ideally biocompatible. This work presents a study of the spinel phases across the (Zn,Mg)Fe2O4 system and of their suitability to be used as magnetic component in hybrid composites. Spinel single phase materials with variable particle size across the submicron range, down to the verge of the nanoscale, have been obtained by mechanochemically assisted synthesis for five selected compositions spanning the whole ZnFe2O4-MgFe2O4 system. Evolution of the crystal lattice and inversion degree (amount of Fe3+ at tetrahedral site) has been obtained from Rietveld refinement of synchrotron X-ray diffraction data, and correlated with the development of magnetic ordering. Ferrimagnetic compositions are identified, among which Zn0.25Mg0.75Fe2O4 stands out for its magnetization characteristics comparable to NiFe2O4. This spinel compound is thus a promising environmentally-friendly candidate for flexible devices, in principle also biocompatible.

Characteristics of NixCoxMgxCuxZn1-4xO nanomaterials: Their structural and magnetic properties and functional attributes

The current study evaluates the photocatalytic, structural, morphological, optical, and magnetic characteristics of the NixCoxMgxCuxZn1-4xO nanomaterials (x = 0.000–0.010). The NixCoxMgxCuxZn1-4xO nanomaterials were synthesized using the temperature-assisted co-precipitation technique. The characteristics of the NixCoxMgxCuxZn1-4xO nanomaterials were investigated using X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectroscopy, and Vibrating sample magnetometer (VSM). XRD analysis revealed dopant incorporation into the ZnO crystal structure, affecting lattice parameters. Magnetic behavior transitioned from diamagnetic to a combination of diamagnetic and ferromagnetic with increasing dopant levels. The optical band gap decreased as dopant concentration increased. Notably, the nanomaterial with x = 0.001 exhibited optimal photocatalytic performance, degrading 98.9 % of Rhodamine B within 20 min under UV light. This nanomaterial also showed efficacy against Methyl Orange and Congo Red, with hydroxyl radicals playing a crucial role in pollutant removal. These findings provide the exceptional reusability and stability of the NixCoxMgxCuxZn1-4xO nanomaterials (x = 0.001)

Magneto-electronic and optoelectronic attributes of half-Heusler VXPt (X = Br, Se) alloys: A first-principles study

High-spin polarized magnetic materials might be useful in spintronics applications. The spin-polarized magnetic, optical, electronic and structural attributes of half-Heusler VXPt (X = Br, Se) alloys were theoretically explored and calculated using the WIEN2k code. The ground states of the structures are optimized, and the bulk moduli and lattice constants are computed. The values obtained from the formation energies show their stability. For VBrPt, an energy gap is present in major and minority spin carriers, while for VSePt, major spin carriers exhibit an energy gap and metallic character is seen in minority spin carriers. The band structures are further illustrated deeply through the investigation of density of states. The electron density graphs depict the ionic bonding in both alloys. The magnetic moments are additionally assessed, and the recorded values support the magnetic characteristics of VBrPt and VSePt. The assessment of how the studied alloys react to light is determined by computing various parameters. The imaginary component and absorption coefficient anticipate substantial light absorption within the visible region. The calculated outcomes unveiled the potential of the examined alloys for applications in spintronics.

Unveiling the magnetic structure of BaFeO3-y: Shedding light on the elusive magnetic behavior

This work provides a comprehensive examination of the structural and magnetic properties of 6H-BaFeO2.96 over a wide temperature range (10 K < T < 300 K) using neutron and synchrotron X-ray diffraction. Additionally, the local oxidation state of iron is examined using electron energy loss spectroscopy. No structural changes that could indicate a charge-order transition are observed in spite of a reported possible charge disproportionation of Fe4+ into Fe(4+δ)+ and Fe(4-δ)+ phenomenon at low temperature. According to the magnetic characterization, BaFeO2.96 orders antiferromagnetically at TN=156 K. The application of external magnetic fields strongly influences the magnetic behavior; the transition temperature shifts to lower values with the applied magnetic field and the long-range magnetic order melts with an applied field of 14 T. The magnetocaloric effect clearly shows at TN a change from negative to positive magnetic entropy. The Rietveld refinement of the neutron powder diffraction data collected at 10 K, gives a magnetic ordering with propagation vector [0, 0, ½] and three magnetically distinct sites for the Fe atoms. This magnetic structure consists of ferromagnetic Fe-sheets perpendicular to the c-axis with the magnetic moments along the [110] direction coupled both ferromagnetic and antiferromagnetically along the c-axis. The magnetic moment values of the three Fe ions are very different evidencing a delicate equilibrium of competing magnetic interactions.

Influence of gadolinium doping on structural, optical, and magnetic properties of CuS nanostructures

To examine the effect of rare earth ions on CuS nanostructures, a series of Gadolinium-doped copper sulphide (Cu1-xGdxS) nanostructures were synthesized through the hydrothermal method. These nanostructures were prepared at x = 0, 1, 3, 5, and 7 at. % concentrations. The prepared samples’ structural, optical, and magnetic characteristics were investigated. Powder X-ray diffraction and Raman analysis were performed to examine the structural analysis of the samples and confirm the existence of a covellite phase hexagonal structure. XPS analysis was conducted to study the valence states. Observations of the surface morphology study from FESEM reveal the formation of flower-shaped structures resembling nanospheres, while at lower magnification nanoflakes were observed. Optical reflectance spectra were recorded using UV–Vis spectroscopy, which showed the increase in bandgap as the concentration of Gd rises. The fluorescence spectrophotometer was utilized for the analysis of room-temperature photoluminescence. The prepared samples showed significant emission peaks at 435 nm. Fluorescence lifetime studies were carried out to confirm the fluorescence decay of CuS nanostructures doped with Gd. Magnetic measurements revealed that prepared samples exhibit an unexpected superparamagnetic nature at room temperature.