Magnetic Hysteresis Loops Research Articles

Magnetic interaction in Sr0.7La0.3Fe11.75Co0.25O19–CoFe2O4 composite system: observation, evidence, and influence

(100-x) Sr0.7La0.3Fe11.75Co0.25O19–(x) CoFe2O4 composites were synthesized by the one pot sol–gel auto-combustion method. The individual phase purity, morphology, and magnetic hysteresis loop of the composite magnet were analyzed by x-ray powder diffraction, field emission scanning electron microscopy and vibrating sample magnetometer, respectively. The apparent observation of the room temperature hysteresis loop indicates the existence of interfacial exchange interactions. Nevertheless, saturation magnetization (Ms ) follows the trend of Vegard’s law. The nature of magnetic interaction and its dependency on the amount of each phase were analyzed by employing the Thamm–Hesse plot. The critical size of the soft phase particle did not corroborate with the results of ΔM vs H plot. However, this synthesis method is found to be successful in obtaining single-step magnetization reversal in hard–soft composite magnets. The deviation from ideal non-interacting Stoner–Wohlfarth particles puts the single hard phase into the limelight. The (BH)max in the range of 1.07–0.98 MGOe has been obtained for the synthesized composite magnet.

Influence of GO content on the optical, magnetic and dielectric properties of the BaFe12O19/GO nanocomposites

In this research, BaFe12O19/GO (GO:10, 20, 40, and 50 wt%) nanocomposites were synthesized by sol–gel auto combustion method and their structural, optical, magnetic and dielectric properties were investigated. The x-ray diffraction results for all nanocomposites validate the formation of a hexagonal phase of Ba hexaferrite. The crystallite size decreased with incorporation of graphene oxide (GO) in the hexaferrite phase and making the nanocomposites. In the FESEM analysis, a change in the surface morphology was observed with an increase in the percentage of GO for samples BFO-40GO and BFO-50GO. The band gap energy of the nanocomposites decreased with increasing the amount of the graphene oxide. Measurements of the magnetic hysteresis loop for all nanocomposites were conducted using a vibrating sample magnetometer at room temperature. By increasing the percentage of GO, a decrease in the saturation magnetization was observed for the samples. A decrease in dielectric constant and loss function were also detected at low frequencies when the GO continent goes up. The nanocomposite sample of BFO-40GO exhibited the highest observed value for real part of the Modulus.

Multifunctional Characterization and Anticancer Properties of Magnetic Zinc Ferrite Nanoparticles by Modified Ultrasonic Assisted Co-precipitation Method

Zinc Ferrite (ZnFe2O4) nanoparticles were synthesized successfully via the modified ultrasonic-assisted co-precipitation method. Structural characterization, conducted through X-ray diffraction (XRD) analysis and Rietveld refinement, revealed a single cubic phase with a mixed spinel structure. Fourier transform infrared spectroscopy confirmed the presence of functional groups indicative of the spinel ferrite structure. Morphological analysis using field-emission scanning electron microscopy showcased the nanoparticles’ uniform morphology and size distribution. UV–vis spectra revealed the optical properties, while the Tauc Plot method determined the optical band gap. Electron paramagnetic resonance spectra confirm the symmetric resonance peak with 1254 Oe line width and the Lande g value 2.133. Magnetic hysteresis loops confirm the soft magnetic nature of the nanoparticles with magnetic saturation and coercivity of 39.2 emu gm−1 and 77.5 Oe. The anticancer properties against various cancer cell lines (HeLa, HepG-2 and MCF-7) revealed significant anticancer activity against HepG-2 and HeLa cells compared to MCF-7 cancer cells, and the results were compared with the standard drug cisplatin. A comparative analysis of results among cancer cell lines was conducted and discussed.

Influence of annealing treatment on grain growth, texture and magnetic properties of a selective laser melted Fe-6.5 wt% Si alloy

The high-density Fe-6.5 wt% Si soft magnetic alloy samples were prepared using selective laser melting (SLM) technology. Annealing treatments with different temperatures were employed to promote grain growth. The microstructure, texture and magnetic hysteresis loops were characterized, aiming to investigate the relationship between microstructure and magnetic properties. The as-printed Fe-6.5 wt% Si alloy had weak texture and low density of ordered phases, and was featured by coarse grains in the top-view section and columnar grains in the side-view section. After annealing at 800 °C–1000 °C, the textures were slightly weakened, while the grain growth was not significant. Increasing the annealing temperature to 1100 °C led to abnormal grain growth behaviors. The grains of the as-printed Fe-6.5 wt% Si alloy showed randomly abnormal growth behaviors rather than oriented growth, which may be related to the low stored energy and initial size advantage before annealing. After annealed at 1100 °C for 1 h, the abnormal grain growth and the formation of large Goss ({110}<001>) and Cube ({100}<001>) grains resulted in microstructure coarsening and texture optimization. Thus, the corresponding ring-shaped sample exhibited excellent magnetic performance. The magnetic induction B8 is 1.21 T, the maximum relative permeability is 14.71 × 103 and the core loss P10/50 is 11.69 W/kg.

Modulated magnetostriction and multiferroic properties in the PVDF-based cobalt ferrite particulate composites

Multiferroic materials (MFM) have drawn substantial attention for developing smart magnetodielectric devices. Herein, cobalt ferrite CoFe2O4 (CFO) was synthesized by a glycine–nitrate sol-gel auto-combustion route and, PVDF-based particulate composite films embedded with CFO have been developed. A comprehensive investigation evaluated the effects of magnetostriction, initiated from the embedded CFO phase, on magnetodielectric characteristics of composite films. The structural, electrical, magnetostrictive and magnetodielectric properties were investigated. The embedded CFO particulate endows PVDF matrix at a higher β–phase forming ability, which enhances the ferroelectricity with a polarisation (Pmax∼1.09 μC/cm2@ 850 kV/cm), a higher dielectric constant (εr∼12.33) and lower dielectric loss. The typical magnetic hysteresis loop was obtained with saturation magnetization (MS∼4.96 emu/g) and coercivity (HC∼1.49 kOe), revealing the ferromagnetic ordering in composite films. The response of the magnetodielectric (MD) is observed at room temperature, that is, a large negative MD coefficient ∼2.1 % @ Hcr∼5.0 kOe is achieved for Co0.9Fe2.1O4/PVDF composite films, while MD∼0.65 %@ Hcr∼1.0 kOe is obtained for Co1.1Fe1.9O4/PVDF films, accompanied by a maximum MD∼4.35 % at resonance frequency. The variation in the MD performance reveals a close correlation to the modulated magnetostriction, such as the magnetocrystalline anisotropy, field-induced coefficient and magnetostrictive susceptibility, indicating the strain-mediated coupling MD effect. The multiferroic properties in CoxFe3–xO4/PVDF composites have potential for magneto-dielectric sensing applications. Furthermore, this work would be exploited to understand MD coupling mechanism and develop MFM for multifunctional devices.

Preparation of BaTiO3/Y3Fe5O12 bilayers and their ferroelectric/magnetic properties

The converse magnetoelectric effect in the ferroelectric/ferrimagnetic bilayers shows a great promise for realizing energy efficient, dense, and fast information storage and processing. In this study, we prepare the hybrid structures consisting of a ferroelectric layer BaTiO3 (BTO) and a ferrimagnetic insulator layer Y3Fe5O12 (YIG) via magnetron sputtering technique and post-annealing procedure. A visible ferroelectricity hysteresis loop for the BTO film and an apparent magnetic hysteresis loop for the YIG film are obtained. Moreover, by capping a platinum layer on the hybrid structures and performing longitudinal spin Seebeck measurements, a detectable spin-charge conversion voltage is observed, and even significant manipulation of this conversion in BTO/YIG/Pt trilayers is achieved by electrical means. These results show great potential for the development of tunable YIG-based devices and are instructive for future artificial multiferroic heterostructures devices applications.

Estimation of the time resistance of steel by the parameters of the harmonic spectrum of the remagnetization curve

The paper presents the results of laboratory studies of structural steels. The possibility of application of complex parameters obtained on the basis of harmonic components of magnetic hysteresis loop for practical estimation of steel time resistance is shown. Determination of the value of the complex parameter is carried out by means of the method of separation of diagnoses in the feature space and the method of group accounting of arguments. Registration of magnetic hysteresis loops is carried out by means of magnetic structuroscope DIUS-1.15M. The weight coefficients of the influence of harmonic components on the value of the complex parameter were determined. The results of the study demonstrate the possibility of satisfactory estimation of the strength of steel by the value of the complex parameter.

Ferroelectricity‐Induced Surface Ferromagnetism in Core–Shell Magnetoelectric Nanoparticles

Magnetoelectric nanoparticles (NPs) present an important class of nanomaterials with a wide interest in piezocatalytic and biomedical applications. Herein, the results of magnetoelectric and magnetization measurements performed on core–shell NPs having magnetic core (MnFe2O4, MFO) and ferroelectric shell (Ba0.85Ca0.15Ti0.5Zr0.5O3, BCZT) synthesized by the microwave hydrothermal method are reported. Magnetic results are compared with the measurements on reference MFO NPs prepared under identical conditions. Detailed SQUID magnetometer measurements of the magnetization hysteresis loops M(H) down to 2 K reveal the existence of a clear exchange bias effect in pure MFO NPs attributed to the coexistence of ferromagnetic and antiferromagnetic short‐range interactions. When the magnetic core is covered by the thin ferroelectric BCZT shell, it is observed that 1) the shell suppresses the apparent bias effect and 2) induces an “extra” ferromagnetic magnetization at T &lt; 20 K. The results indicate that this “extra” ferromagnetism has a 2D character and it is most likely related to the interface interactions between the MFO core and BCZT shell. Ferroelectric properties and strong magnetoelectric effect in core–shell NPs are revealed via piezoresponse force microscopy under magnetic field. The mechanisms of the observed effects are discussed.

Nature-based solutions for monitoring the impact of vehicular particulate matter and for the preventive conservation of the Palatine Hill archaeological site in Rome, Italy

Magnetic and chemical biomonitoring methodologies were applied to the southern slopes of the Palatine Hill archaeological area in Rome, Italy. Plant leaves and lichen transplants were respectively sampled and exposed between July 2022 and June 2023 to assess the impact of vehicular particulate matter from Via dei Cerchi, a trafficked road coasting Circus Maximus, towards the archaeological area upon the Palatine Hill. The magnetic properties of leaves and lichens, inferred from magnetic susceptibility, hysteresis loops and first order reversal curves, were combined with the concentration of trace elements. It was demonstrated that the bioaccumulation of magnetite-like particles, associated with tracers of vehicular emissions, such as Ba and Sb, decreased with longitudinal distance from the road, without any important influence of elevation from the ground. Lichens demonstrated to be more efficient biomonitors of airborne PM than leaves, irrespective of the plant species. Conversely, leaves intercepted and accumulated all PM fractions, including road dusts and resuspended soil particles. Thus, plant leaves are suitable for providing preventive conservation services that limit the impact of particulate pollution on cultural heritage sites within busy metropolitan contexts.

Tunable Magnetic and Dielectric Properties of BaMg0.4Al0.4Fe11.2O19 and SiO2 Composites for High-Frequency Applications

This study focuses on the synthesis and characterization of Mg and Al co-doped M-type Barium hexaferrite (BaMg0.4Al0.4Fe11.2O19) powder via the sol-gel method. Structural analysis using X-ray diffraction (XRD) and Fourier transformation infrared spectroscopy (FTIR) confirmed the single-phase structure of the synthesized powder. Morphological properties were examined through field emission scanning electron microscopy (FESEM), revealing hexagonal particle morphology with an average size of approximately 60 nm for BaMg0.4Al0.4Fe11.2O19. To fabricate composites, commercially purchased SiO2 was used to prepare the composites of (1–x) BaMg0.4Al0.4Fe11.2O19+ (x) SiO2 {where x = 0.0, 0.1, 0.3, 0.5 and 0.7). The composites were prepared using the mixing method followed by microwave sintered at 1000 °C/90 min. FESEM and energy-dispersive X-ray spectroscopy (EDS) were employed to analyze the morphology and elemental composition of the composites. The composites ‘ frequency-dependent complex permittivity was measured over 300 kHz to 3 GHz. Magnetic hysteresis (M-H) loops were used to analyze the magnetic properties of composite samples. A reduction in magnetic saturation was observed with increasing SiO2 concentration, while there was a slight increase in coercivity for the composite samples compared to pure hexaferrite. Coercivity remained relatively unchanged with varying SiO2 concentrations in the composites. A possible relation between the magnetic and dielectric properties and the microstructure of the sintered composites with the composition variation was investigated.

High photocatalytic degradation of methylene blue and enhancing the magnetization, AC conductivity of Dy3+ and Ce3+ doped CdCoFe2O4 nano ferrites

Photocatalysts that combine with dielectric and magnetic properties are vital because of a wide variety of applications for these combinations, and nanostructured magnetic semiconductive materials have attracted significant interest due to their potential applications. A series of Cd0.4Co0.6DyXCeXFe2-2XO4 spinel nano ferrites (nFs) were synthesized by using a highly efficient low-temperature method of citrate sol-gel auto-combustion for Methylene Blue (MB) dye degradation photocatalysts under visible light irradiation that combines with dielectric and magnetic properties are vital because of a wide variety of applications for these combinations, and nanostructured magnetic semiconductive materials have attracted significant interest due to their potential applications. The recycled MB is one of the hazardous textile dyes that is used extensively but causes risks for both humans and the environment. The prepared Dy3+ and Ce3+ doped Cd–Co nFs were polycrystalline with cubic structure, and crystalline size was increased from 15.78 to 21.02 nm with higher crystallinity, and the surface morphology changes from a spherical shape to a hexagonal shape with higher doping concentrations. The direct optical band gap values are increased. FTIR spectra reveal the stretching vibrations along the [M↔O] bond tetrahedral (A) and octahedral (B) sites. HRTEM results revealed that the prepared Cd–Co nFs have higher crystalline nature and high porosity. VSM indicates the sample's soft magnetic action and hysteresis loops showed the highest saturation magnetization (Ms) is 12.243 emu/g, and retentivity increases around 6.038 emu/g, decreasing the dielectric tangent loss, dielectric constant and dielectric loss. The AC conductivity raised with applied frequency. The PL gives a blue emission, and photocatalytic has the highest degradation activity 40.93 % of MB would be successful after 120 min irradiation of X = 0.07 Dy3+ and Ce3+ doped Cd–Co nFs.

Anomalous magnetic behavior in MnFePSi glass-coated microwires

We studied the MnFePSi glass-coated microwires (GCMWS) prepared by using Taylor–Ulitovsky technique at low magnetic fields and low temperatures. While regular ferromagnetic behavior has been observed at room temperature, anomalous magnetic behavior is observed for the glass-coated microwires samples. Notable metamagnetic phase transition is observed for bulk alloy sample from the magnetic hysteresis loops measured at 5 K. Meanwhile, extraordinary metamagnetic phase transition is seen at hysteresis loops measured at temperature below 100 K. In addition, M-H loops show harder magnetic properties compared to the bulk sample, where the coercivity, Hc, of glass-coated microwire is about 64 times higher than the one reported in bulk alloy. Additionally, the hysteresis loops of glass-coated microwires measured at temperature lower than 100 K show multistep magnetic behaviour. Zero Field Cooling (ZFC), Field Cooling (FC) and Field Heating (FH) curves of bulk samples show totally different magnetic behaviour compared to the microwire sample measured at the same conditions due to the different microstructure phases for the bulk and microwires samples. The present findings demonstrate the significant impact of drawing, quenching and stresses induced by glass-coating on the microstructure and magnetic characteristics of MnFePSi-metallic alloys as compared to their bulk form. Furthermore, we confirmed that, in contrast to the bulk form constraint, the Taylor-Ulitovsky process for metallic glass-coating microwires may alter the physical characteristics and extend the applications of MnFePSi alloys.

Strong magnetoelectric coupling in novel Na0.5Bi0.5TiO3–BaFe12-2xCoxTixO19 multiferroic composite

Multiferroic composites of sol-gel synthesized Sodium Bismuth Titanate (Na0.5Bi0.5TiO3) and Co–Ti substituted Barium Hexaferrite (BaFe12-2xCoxTixO19; x = 0.0, 0.5, 1.0, 1.5 and 2.0) in the ratio 3:1 was synthesized through ceramic route. Successful formation of R3c rhombohedral and P63/mmc hexagonal phases corresponding to Na0.5Bi0.5TiO3 and BaFe12-2xCoxTixO19 respectively was confirmed from the XRD and Rietveld refinement pattern. The frequency and temperature dependence of dielectric constant and loss of the composite systems exhibited typical dispersion behaviour which could be understood using the Maxwell-Wagner model. Substituted samples showed enhanced dielectric behaviour where dielectric constant was observed to increase while loss tangent decreased. Using the Universal Jonscher's Power law (JPL), conductivition mechanisms of the composite systems were studied from the ac conductivity behaviour which revealed that the x = 0.0 sample followed Non-overlapping Small Polaron Tunnelling (NSPT) model while the remaining samples followed the Correlated Barrier Hopping (CBH) model. The complex impedance and Nyquist plot analysis showed the enhancement of resistive property in the x≠0 systems. Magnetic hysteresis loop measurements were conducted, and the associated parameters were determined with the assistance of the Law of Approach to Saturation (LAS). Favourable reduction in the magnetic anisotropy was observed indicating the disturbance of magnetic spin structure in the hexaferrite phase. The P-E loops established the novel room temperature multiferroic nature of the composite systems. Significant magnetoelectric coupling was detected at room temperature in all samples, with the x = 0.5 sample exhibiting the highest value of approximately 59.81 mV/cmOe. These desirable properties suggest that the composites may find future device applications as in magnetically tunable energy harvesting devices and self-powered magnetoelectric sensors in the future.

Effects of Mg Substitution on the Structural with Rietveld Analysis, Magnetic and Magnetocaloric Properties of Ni-Cu-Cd Bulk Ceramics

Bulk ceramics with optimized density are highly prioritized over ferrite nanoparticles to fabricate devices for their optimal magnetic saturation, lower coercivity, and anisotropy, enhanced resistance, etc. To achieve such bulk specimen using Ni0.5-yMgyCu0.2Cd0.3Fe2O4 disc samples are sintered at 1423 K keeping the heating and cooling rate at 10 K and 5 K respectively. In due course, structural as well as theoretical Rietveld analysis, optical, and magnetic properties have been analyzed using these bulk samples. XRD has explored structural properties and after that these values have analyzed with the Rietveld refinement procedure and obtained goodness of χ2 (1–2) value and other parameters such as lattice parameters, crystal structures, cation distribution, and maximum entropy mapping. Surface morphology and grain size have examined from the as-grown surface without further polishing and annealing by electron microscopy and revealed a decreasing trend of grain size 6.1 µm to 4.2 µm. UV–Vis spectroscopy characterization ensured optical properties for bulk as well as nanopowders and the band gap has been found in the range of 1.4 to 1.6 eV and is increasing with Mg content. Magnetic hysteresis loop exhibits a less decreasing nature up to y = 0.3 of magnetic saturation along with the Law of Approach to saturation which compiles magnetic anisotropy. The temperature-dependent magnetization curves exhibit a sharp decreasing value (i.e. dM/dT maximum) at Curie point, decreasing from 630 K to 505 K with increasing Mg content. At.3 T magnetic field the changes in relative cooling power value have been found in the range 53.82Jkg-1 to 37.79Jkg-1 which could be considered as potential for magnetocaloric refrigeration.

Coexistence of Ferromagnetism and Superconductivity at KTaO3 Heterointerfaces.

The coexistence of superconductivity and ferromagnetism is a long-standing issue in superconductivity due to the antagonistic nature of these two ordered states. Experimentally identifying and characterizing novel heterointerface superconductors that coexist with magnetism presents significant challenges. Here, we report the observation of two-dimensional long-range ferromagnetic order in a KTaO3 heterointerface superconductor, showing the coexistence of superconductivity and ferromagnetism. Remarkably, our direct current superconducting quantum interference device measurements reveal an in-plane magnetization hysteresis loop persisting above room temperature. Moreover, first-principles calculations and X-ray magnetic circular dichroism measurements provide decisive insights into the origin of the observed robust ferromagnetism, attributing it to oxygen vacancies that localize electrons in nearby Ta 5d states. Our findings suggest KTaO3 heterointerfaces as time-reversal symmetry breaking superconductors, injecting fresh momentum into the exploration of the intricate interplay between superconductivity and magnetism enhanced by the strong spin-orbit coupling inherent to the heavy Ta in 5d orbitals.

Phase transition, structural and magnetic parameters of vanadium-substituted Bi0.9Sm0.1FeO3 multiferroic ceramics

ABSTRACT The inorganic multiferroic compounds Bi0.9Sm0.1Fe1 − x V x O3 (x = 0.0, 0.015, 0.03, and 0.045) were prepared by the solid-state reaction method. X-ray diffraction analysis confirmed the rhombohedral perovskite-like structure with minor traces of the impurity phases Bi2Fe4O9 and Bi25FeO40. The lattice parameters a and c, and the volume of the hexagonal unit cell were extracted from the X-ray diffraction data and found to increase as the V5+ content is increased. The average crystallite size was estimated to be in the range 380–415 Å. Fourier transform infrared spectroscopy confirmed the rhombohedral perovskite-like structure via the vibration bands of the octahedral FeO6 group observed between 410 and 570 cm−1. A differential scanning calorimeter was used to record the thermal scans which revealed that the compounds have undergone crystalline phase transitions at temperatures in the range 300–320°C. A 4.5% V + 5 substitution has shifted the transition peak by 20°C. The magnetic hysteresis loops taken at room temperature with a vibrating sample magnetometer revealed the ordinary ferromagnetic behavior. The V5+ substitution enhanced the remanent magnetization, but the magnetic coercivity was found to fluctuate around an average value of about 1000 Oe. The compound Bi0.9Sm0.1Fe0.955V0.045O3 exhibited the maximum remanent magnetization.

Simultaneous synthesis of super-paramagnetic hydrochar in a one-pot using subcritical water medium and evaluation of its photocatalytic activity

The unregulated release of chemical dyes into the environment presents considerable environmental hazards when left untreated. Photocatalytic degradation, acknowledged as an eco-friendly and cost-effective method, has garnered attention for its efficacy in eliminating organic pollutants like dye. Consequently, the development of multifunctional materials with different applications in environmental and catalytic fields emerges as a promising avenue. Recognizing the significance of integrating catalysts and porous materials for enhancing interactions between pollutants and photo-sensitive substances, magnetic hydrochar emerges as a solution offering heightened efficiency, scalability, recyclability, and broad applicability in various environmental processes, notably wastewater treatment, due to its facile separation capability. In this study, Fe3O4-based, super-paramagnetic hydrochar (SMHC) was simultaneously synthesized in a single step using a coconut shell in the subcritical water medium. A thorough analysis was conducted on both raw hydrochar (RHC) and SMHC to unravel the mechanism of interaction between Fe3O4 nanoparticles and the hydrochar matrix. The synthesized hydrochar exhibited super-paramagnetic characteristics, with a saturation magnetization of 23.7 emu/g and a magnetic hysteresis loop. SMHC displayed a BET surface area of 42.6 m2/g and an average pore size of 26.3 nm, indicating a mesoporous structure according to nitrogen adsorption-desorption isotherms. XRD analysis revealed magnetic crystal sizes in the obtained SMHC to be 13.7 nm. The photocatalytic performance of SMHC was evaluated under visible light exposure in the presence of H2O2 for Astrazon yellow (AY) dye degradation, with optimization conducted using response surface methodology (RSM). The most substantial dye removal, reaching 92.83%, was achieved with 0.4% H2O2 at a 20 mg/L dye concentration and an 80-min reaction duration.

Open-source device for high sensitivity magnetic particle spectroscopy, relaxometry, and hysteresis loop tracing.

Magnetic nanoparticles (MNPs) are used extensively across numerous disciples, with applications including Magnetic Particle Imaging (MPI), targeted hyperthermia, deep brain stimulation, immunoassays, and thermometry. The assessment of MNPs, especially those being designed for MPI, is performed with magnetic particle spectrometers, relaxometers, loop tracers, or similar devices. Despite the many applications and the need for particle assessment, there are few consolidated resources for designing or building such a MNP assessment system. Here, we describe the design and performance of an open-source device capable of spectroscopy, relaxometry, and loop tracing. We show example measurements from the device and quantify the detection sensitivity by measuring a dilution series of Synomag-D 70nm (from 0.5 mg Fe/ml to 7 ng Fe/ml) with a 10 mT drive field at 23.8kHz. The device measures 260pg Fe with SNR = 1 and 1.3 ng at SNR = 5 in spectroscopy mode in under one second of measurement time. The system has a dynamic range of 60 μg to 260pg Fe without changing the hardware configuration. As an example application, we characterize Synomag-D's relaxation time constant for drive fields 2-18 mT and compare the magnetization responses of two commonly used MNPs.

Dual-phase superconductivity in high-pressure high-temperature synthesized TaNbZrHfTi

We report on a novel TaNbZrHfTi-based high entropy alloy (HEA) which demonstrates distinctive dual-phase superconductivity. The HEA was synthesized under high pressures and high temperatures starting from a ball milled mixture of elemental metals in a large-volume Paris–Edinburgh cell with P ≈ 6 GPa and T = 2300 K. The synthesized HEA is a phase mixture of BCC (NbTa)0.45(ZrHfTi)0.55 with Tc1 = 6 K and FCC (NbTa)0.04(ZrHfTi)0.96 with Tc2 = 3.75 K. The measured magnetic field parameters for the HEA are lower critical field, Hc1(0) = 31 mT, and a relatively high upper critical field, Hc2(0) = 4.92 T. This dual-phase system is further characterized by the presence of a second magnetization peak, or the fishtail effect, observed in the virgin magnetization curves. This phenomenon, which does not distort the field-dependent magnetization hysteresis loops, suggests intricate pinning mechanisms that could be potentially tuned for optimized performance. The manifestation of these unique features in HEA superconductivity reinforces phase-dependent superconductivity and opens new avenues in the exploration of novel superconducting materials.

Tunable superconductivity in fluorine-functionalized molybdenum carbide

Two-dimensional transition metal carbide, molybdenum carbide (Mo2C), has been explored for applications in catalysts, energy storage devices, and superconductors. Generally, selectively etching Ga from Mo2Ga2C in HF solution is the most popular method for synthesizing Mo2CTx, where Tx represents the surface functional group (−O, –OH, –F). The functional groups on their surface strongly influence the density of states on the Fermi surface and thereby the electronic structure. Therefore, tailoring the surface functionalization demonstrates a great potential for tuning the electronic properties of Mo2C. To precisely investigate the effect of the fluorine functional group on the superconductivity of Mo2C, we adopted the topochemical method to synthesize 2D Mo2C. The fluorine-functionalized Mo2C was obtained by sintering the mixture of Mo2C and NH4F in different ratios, in which NH4F was considered a fluorine source. Due to the strong electronegativity of fluorine, the surface of Mo2C was easily functionalized by fluorine. Notably, the superconductivity of Mo2C was enhanced by increasing the fluorine content and reached the highest Tc value of 5.7 K, compared with 3.2 K of pure Mo2C. A clear magnetization hysteresis loop was observed at 2.0 K, indicating a typical type-II superconductor.