Journal of Superconductivity and Novel Magnetism最新文献

Plant-mediated nanoparticles gaining importance due to their broad spectrum of pharmacological applications in comparison to the synthetic drugs. The nanoparticles amalgamated using plant extracts have been receiving much attention due to the robust phytochemicals and therapeutic potential. Thus, we herein report the biosynthesis and pharmacological evaluation (anti-oxidant, anti-inflammatory, anti-platelet, and anti-cancer properties) of Decalepis hamiltonii leaves extract copper ferrite nanoparticles (DHLE-CuFe₂O₄ NPs). The characterization of DHLE-CuFe₂O₄ NPs was carried out using Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy-dispersive X-ray analysis (EDAX), High-resolution transmission electron microscopy (HR-TEM), and Vibrating sample magnetometer (VSM). DHLE-CuFe₂O₄ NPs exhibited anti-oxidant activity by scavenging 1,1-diphynyl-2-picrylhydrazyl (DPPH) radicals (66.46%) and reduced ferric to ferrous ions at the concentration of 150 μg/mL. Furthermore, DHLE-CuFe₂O₄ NPs restored the NaNO₂-induced oxidative stress markers such as lipid peroxidation, protein carbonyl content, total thiol, and anti-oxidant enzyme (catalase and super oxide dismutase) activities in RBCs. DHLE-CuFe₂O₄ NPs were non-toxic as it did not cause RBCs lysis, while it exhibited anti-inflammatory activity by inhibiting heat-induced hemolysis, egg albumin, and bovine serum albumin denaturation. In addition, DHLE-CuFe₂O₄ NPs inhibited ADP and epinephrine-induced platelet aggregation. Most importantly, DHLE-CuFe₂O₄ NPs showed anti-cancer potential by eliciting cytotoxic effect to MCF-7 cells in a dose-dependent manner. Further, DHLE-CuFe₂O₄ NPs caused apoptosis to MCF-7 cells which was confirmed by annexin V/PI staining test and flow cytometer. In conclusion, DHLE-CuFe₂O₄ NPs regulate oxidative stress-induced red blood cell damage, thrombosis, inflammation, and MCF-7 cells growth.

Two principal physical properties of La₂CuO₄ and YBa₂Cu₃O₆ are identified, which can promote the emergence of superconductivity in unconventional high-temperature superconductors. The first property is a specific type of chemical bonding stimulating fluctuations of the charge density. To reveal it, it is necessary to carry out calculations of the electronic band structure and find the parameters of critical points in the charge density distribution in the crystal. For calculation of the electronic band structure of YBa₂Cu₃O₆ the same approach was applied, which we earlier used for the study of the electronic band structure of La₂CuO₄ and high-temperature superconductors: computer program WIEN2k and exchange potential of Becke and Johnston modified by Tran and Blaha. Such approach allowed us to obtain the antiferromagnetic ground state for the compound YBa₂Cu₃O₆ with a band gap E_g = 1.5 eV and a magnetic moment on copper atoms M_Cu = 0.71 μ_B. It turned out that YBa₂Cu₃O₆ compound has a type of chemical bonding similar to that which we found earlier in La₂CuO₄ and in high-temperature superconductors. Consideration of the symmetry properties of the crystal structures of the La₂CuO₄ and YBa₂Cu₃O₆ compounds revealed a second characteristic property of them – the existence of magnetic crystal classes that admit a linear magnetoelectric effect. This effect allows the simultaneous existence of local magnetic fields and electric polarization in the sample. Based on two identified characteristic physical properties of the La₂CuO₄ and YBa₂Cu₃O₆ compounds, a roadmap is proposed for a search of new parent substances for obtaining unconventional high-temperature superconductors.

The ({J}_{1}-{J}_{2}) frustrated two-dimensional Ising antiferromagnet in the magnetic fields on the square lattice is studied using a functional integral method. First, we determine possible ground states of the model including Néel antiferromagnetic phase and striped antiferromagnetic phase, which depend on the value of the frustrated parameter (alpha ={J}_{2}/{J}_{1}). The influence of the spin fluctuations in the presence of the frustration, temperature, and longitudinal and transverse fields on these two phases is also studied, which shows the strong impact of the spin fluctuations at the phase transition points. The effects of the longitudinal and transverse fields are highlighted. In addition, we also calculate and plot the temperature dependence of the magnetic susceptibility, and we find a sharp peak related to a phase transition and a rounded peak related to the competition of the effects of the antiferromagnetic exchange couplings, temperature and fields. Hence, we suggest experimental relevance for the given theoretical model with Li₂VOSiO₄ and YbBi₂IO₄.

This study employs first-principles calculations to explore the structural, elastic, electronic, magnetic, and optical properties of the quaternary Heusler compounds CoFeYSb (Y = V, Ti). The structural analysis confirms that both compounds are most stable in the YI configuration. CoFeVSb is found to exhibit ferromagnetic behavior, while CoFeTiSb shows ferrimagnetism. Elastic constants, cohesion energy, and formation energy calculations further validate the stability of the magnetic (I) phase for both materials. Band structure analysis reveals that these compounds are half-metallic, achieving 100% spin polarization at the Fermi level, with spin-down energy gaps of 0.55 eV for CoFeVSb and 0.61 eV for CoFeTiSb. The total magnetic moments comply with the Slater-Pauling 24-electron rule, with values of 3 μB for CoFeVSb and 2 μB for CoFeTiSb. Optical investigations, including the dielectric function, absorption coefficient, and energy loss function, demonstrate strong absorption in the visible and ultraviolet ranges. These results highlight the potential of CoFeYSb compounds for advanced optoelectronic and spintronic applications, offering new opportunities for their integration into electronic and photonic technologies.

Sc(0,1,2,3 mol%): Ce: Fe: LiNbO₃ crystals were grown by conventional Czochralski method. The X-ray diffraction is used to determine lattice constants and analyze the internal structure of crystals. The lattice size was found to increase first and then decrease, and the doping elements do not alter the crystal structure. The concentrations of Sc³⁺, Ce⁴⁺, and Fe³⁺ ions in the crystals were measured using ICP-AES. With the increase of Sc³⁺ concentration in the melt, the effective segregation coefficient of Sc³⁺ was found to decrease, while the effective segregation coefficient of Ce⁴⁺ and Fe³⁺ increased. The birefringence gradient of the ScCeFe-3 sample measured using the birefringence gradient method was 3.3 × 10⁻⁵ ∆R/cm⁻¹, which was the best optical homogeneity.

The transport and magnetic properties of the Magnéli phase tungsten oxide WO_2.90, prepared via spark plasma sintering, were investigated across a broad temperature range of 4–550 K, including the previously unexplored low-temperature region below 300 K. Microstructure analysis shows that obtained pellets are fully dense, enabling reliable measurement of transport properties. Resistivity measurements reveal typical metallic behavior of WO_2.90 at low temperatures. Above room temperature, resistivity tends to saturate by reaching a maximum value near 430 K. The resistivity saturation indicates that Mott-Ioffe-Regel limit is approached, where the charge carrier mean free path becomes comparable to the interatomic spacing. The temperature dependence of the resistivity can be well described by the phenomenological parallel resistor model. Significant positive magnetoresistance was observed at low temperatures, with an unusual linear dependence on the magnetic field. Despite its metallic conductivity, WO_2.90 displays weak diamagnetism, likely due to the substantial core diamagnetism of tungsten and the bipolaronic pairing of charge carriers.

In electronic models on lattices with strong geometric frustration (flat band models), the band dispersion of electrons can vanish, resulting in what is known as a flat band. Flat bands are known to serve as a platform for the emergence of various intriguing physical properties. Realizing flat bands in actual materials, however, remains a challenging task. In this paper, we report that the flat band model approximately holds in the pyrochlore oxide Pb(_2)Bi(_2)O(_7), as demonstrated by first-principles calculations. Furthermore, we propose that, among the two key parameters in flat band systems—the flat band width and the carrier density—the latter can be selectively controlled, approximately, by utilizing the solid solution Pb(_2)(Sb,Bi)(_2)O(_7). This finding represents a new step toward “flatronics,” a field focused on controlling flat band systems.

The RTX (where R represents rare earth, T represents 3d/4d/5d transition metal, and X represents p-block element) series comprises an extensive collection of equiatomic (1:1:1) intermetallic compounds that exhibit diverse crystal and magnetic structures with their vast array of physical properties, which includes field-induced phase transitions, commensurate, incommensurate, superconductivity, non-trivial topology, etc. In the present work, the exchange interactions and phonon topology of EuAuAs, GdAuGe, and GdAgGe have been discussed. By correlating the spin configurations to the underlying Heisenberg spin model, we have successfully estimated the exchange interactions. Furthermore, by using the mean-field approximation, the Neel temperatures of rare-earth compounds have been reported, which is consistent with the experimental value. The phonon dispersion of EuAuAs and GdAuGe exhibits non-trivial topological phononic states with nodal surfaces and Dirac points on the (k_z) = (pi ) plane. The calculated phonon spectrum of GdAgGe reveals the presence of a nodal line along the (k_z) = (pi ) plane. The exploration of phonon topology opens up a new pathway toward comprehending and harnessing the exotic physical characteristics exhibited by these rare-earth compounds and other analogous quantum materials.

Pr_0.9Sr_0.1MnO₃ was synthesized using the solid-solid method, and its structural and magnetic characteristics were thoroughly examined. The synthesis procedure was meticulously detailed. In the initial phase, structural analysis was conducted employing X-ray diffractometry with copper radiation, alongside magnetization measurements. Magnetic properties were investigated utilizing the BS1 magnetometer, facilitating a comprehensive understanding of the material's behavior. Subsequently, in the second phase, Monte Carlo simulations were employed to explore the magnetic characteristics and magnetocaloric effects of the Pr_0.9Sr_0.1MnO₃ perovskite. This approach provided insights into thermal magnetization, magnetic susceptibility, magnetic entropy changes, relative power cooling, and magnetic hysteresis cycles.