Journal of Superconductivity and Novel Magnetism最新文献

The present work reports the magnetic and structural behavior of [Gd/Co]₁₀ multilayers with different Co thickness values, prepared by magnetron sputtering, as a function of thermal annealing. Intermixing is observed with thermal annealing for all the samples; however, complete intermixing is not observed even after annealing at 773 K. Antiparallel alignment of Gd and Co layer magnetization is observed for pristine samples from room temperature X-ray magnetic circular dichroism measurements. Magnetic compensation temperature is found to vary depending on the thickness of Co layers. Temperature-dependent magneto-optical Kerr effect (MOKE) measurements depict the inversion of loops across magnetic compensation temperature for all the pristine samples. However, no signatures of magnetic compensation are observed in the low-temperature MOKE loops for the annealed samples. MOKE loops of the annealed samples exhibit double hysteresis loops. The results are explained in terms of intermixing with annealing.

The present work focusses on the green synthesis of Co₃O₄ nanoparticles (NPs) using Lepidagathis ananthapuramensis leaf extract and to investigate its structural, optical, morphological and magnetic properties. The structural information confirmed the formation of spinel type polycrystalline cubic symmetry with space group Fd-3 m. The Fourier transform infrared spectroscopic studies revealed the sharp doublet peak in the finger print region pertaining to the Co²⁺ and Co³⁺ ions. The X-ray photoelectron spectroscopy further confirmed the presence of Co³⁺ and Co²⁺ ions in which Co³⁺ ions are present more than Co²⁺ ions. The UV–Visible spectroscopic studies indicate that there are two characteristic absorptions of Co₃O₄ NPs indicating the ligand to metal charge transfer. The morphological analysis of Co₃O₄ NPs using field emission scanning microscope and high-resolution transmission electron microscopy, showed irregular shapes of different sizes with Co mostly at surface than the core. The magnetic data revealed the existence of antiferromagnetic nature co-hosting weak ferromagnetism. The detailed explanations of a straightforward and affordable method for creating spinel type Co₃O₄ and their structural and magnetic properties were explained.

Magnetoresistance (MR), magnetoinductance (mi), and magnetoimpedance (MI) studies on the as-quenched and annealed Fe₇₂Si₁₀Cu₁Nb₂B₁₅, Co₇₂Ni₅Si₅Cu₁Nb₂B₁₅, and Co₇₇Si₅Cu₁Nb₂B₁₅ ribbons have been carried out in the present investigation. Structural studies indicate that all as-quenched samples are in the amorphous phase. The asymmetry in the MI, MR, and mi curves is noticed and is attributed to induced magnetocrystalline anisotropy and hysteretic magnetization. Among all three samples, the Co₇₇Si₅Cu₁Nb₂B₁₅ ribbons exhibit the highest magnetization and MI values. The development of a strong transverse magnetic anisotropy upon annealing has been observed in the Co₇₇Si₅Cu₁Nb₂B₁₅ ribbons, while such features are not observed in other cases. The present study shows that 5% Ni substitution in Co₇₇Si₅Cu₁Nb₂B₁₅ samples significantly reduces the transverse anisotropy, indicating that the transverse anisotropy can be tuned through Ni substitution.

By simulating the thermomagnetization of Ba(Fe_1-xSc_x)₁₂O₁₉ from approximately 100 to 750 K, the magnetocaloric effect (MCE) in Ba(Fe_1-xSc_x)₁₂O₁₉ samples is approximated. Intriguingly, the thermomagnetic property of the undoped sample BaFe₁₂O₁₉ is described as a conventional MCE for high temperatures. However, at doping levels x of 0.128, 0.153, and 0.189, respectively, the thermomagnetic property of Sc-doped samples is defined as an inverse MCE below temperatures of 163, 239, and 318 K. In contrast, thermomagnetic property of Ba(Fe_1-xSc_x)₁₂O₁₉ is described as conventional MCE above those temperatures. Additionally, Sc doping makes it possible for MCE in Ba(Fe_1-xSc_x)₁₂O₁₉ to be strongly tailored. This is helpful for operating a magnetic refrigerator (MR) which occurs in various temperature ranges and results in a higher working temperature range. A promising function for Ba(Fe_1-xSc_x)₁₂O₁₉ samples in MR at high-temperature applications in the automotive and food industries or aerospace.

The scattering eigenstates of any Hamiltonian of electrons, coupled through a two-body force and moving on a one-dimensional lattice, are shown to be Bethe’s wave-functions. The energy of the groundstate is compared with values, obtained previously for the Hubbard Hamiltonian thanks to another Bethe’s wave-function-based procedure and within the framework of the correlated Fermi gas. The same analysis is applied to electrons, interacting on neighbouring sites. The significance of those various groundstates is assessed with help of thermodynamics.

Organic spintronics (OS), which focuses on utilizing the spin degree of freedom in organic materials, has been a fascinating topic because of its technological aspects and future applications. In-plane uniaxial magnetic anisotropy (UMA) is becoming increasingly important in the rapidly developing field of OS. In this study, Cobalt (Co) films were deposited with varying thicknesses on the Tris (8-hydroxyquinolinato) aluminium (Alq₃) layer to investigate the evolution of magnetism and UMA. Magnetic measurements and simultaneous domain imaging have been done using the magneto-optic Kerr effect by varying the azimuthal angle between the easy axis of magnetization and the applied magnetic field. It was discovered that the bilayer exhibits a well-defined UMA in the film plane upon forming a continuous Co film with a thickness of around 10 nm. Structural and morphological properties of all the Co/Alq₃ bilayers were studied using grazing-incidence small-angle X-ray scattering and wide-angle X-ray scattering measurements at synchrotron radiation source, P03 beamline PETRA-III, Germany. The combined analysis revealed that in contrast to the inorganic magnetic polycrystalline thin films, where the UMA originates mainly due to the stress, the origin of UMA in Co/Alq₃ is attributed to the magnetocrystalline anisotropy caused by c-axis (Co (002)) preferential orientation. The surface free energy of Alq₃ is less than that of Co; therefore, the growth of Co starts with island formation, which coalescences with increasing thickness. The observed structure orientation may be attributed to minimizing the magnetoelastic energies due to coalescence known as the zipping effect. The absence of UMA in films with lower thickness film (~5 nm) is understood in terms of random short-range stress caused by isotropic pinning due to the diffused interface.