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First‐principles calculations based on density functional theory (DFT) are performed for investigating the electronic and magnetic properties of a heterostructure formed by Co‐decorated trimesic acid (TMA) self‐assembling network (SAN) adsorbed on graphene. The concentration and spatial position of Co adatom on graphene is regulated by the architecture of SAN. The obtained optimized geometry shows that Co adatom ends up at the top of a C atom on graphene in the heterostructure. The spin‐polarized calculations upon Co‐SAN/G, illustrate that Co adsorption on top site, which is favored by the self‐assembling network, causes an alternating change in the local density of states (LDOS) of graphene that consequently gives rise to sublattice symmetry‐breaking effects reflected in the different gap opening at K K′$K^\prime$ valleys. It is demonstrated that a single Co atom adsorbed on top of a C atom on graphene generates similar physical properties as Co‐SAN/G and, in fact, the SAN acts as a template for patterning Co on graphene without interfering with the magnetic properties originated from the adsorbate. Furthermore, Co atoms in the Co‐SAN/G structure, which are localized on just one sublattice type and separated by 10 Å in a triangular lattice, constitute ferromagnetically aligned spin centers. [ABSTRACT FROM AUTHOR]

Interfacial magnetism in functional oxide heterostructures not only exhibits intriguing physical phenomena but also implies great potential for device applications. In these systems, interfacial structural and electronic reconstructions are essential for improving the stability and tunability of the magnetic properties. In this work, we constructed ultra-thin La0.67Ca0.33MnO3 (LCMO) and SrRuO3 (SRO) layers into superlattices, which exhibited a robust ferromagnetic phase. The high Curie temperature (TC) reaches 291 K, more than 30 K higher than that of bulk LCMO. We found that the LCMO/SRO superlattices consisted of atomically-sharp and asymmetric heterointerfaces. Such a unique interface structure can trigger a sizable charge transfer as well as a ferroelectric-like polar distortion. These two interfacial effects cooperatively stabilized the high-TC ferromagnetic phase. Our results could pave a promising approach towards effective control of interfacial magnetism and new designs of oxide-based spintronic devices. [ABSTRACT FROM AUTHOR]

Cu-doped Co3O4 (1, 3, 5 and 7 wt%) nanoparticles were synthesized through the decomposition of cobalt (II) acetylacetonate, cobalt (III) acetylacetonate and copper (II) acetylacetonate in the least toxic polar solvent through solvothermal method. XRD analysis confirmed the formation of cubic spinel structure with reduced crystallite size of 20 nm and slight lattice expansion upon Cu doping. The spectral analysis carried out by FTIR and Raman studies expressed the existence of functional group and active vibrational modes. UV–Vis analysis revealed the increase in bandgap value with increasing dopant concentration. Slightly dissociated nanosheets and cubic structure were observed in HR-SEM and HR-TEM analyses with an average particle size of 25 nm. SAED pattern indicated the polycrystalline nature of the synthesized nanoparticles. The weak ferromagnetic nature with low coercivity and remanent ratio is deliberated from magnetic measurement. The Cu dopant was found to enhance the electrochemical performance of Co3O4 nanoparticles with high specific capacitance, since it possesses larger surface area due to reduced particle size. [ABSTRACT FROM AUTHOR]

In the current study, Ti-Ni-Cu alloy powders were prepared by mechanical alloying using high-energy planetary ball mill under argon atmosphere. The effects of milling time on the evolution of structure, microstructure, and magnetic properties were analysed. Morphological observations indicated a narrow particle size distribution and homogeneous shape. According to the Rietveld analysis, during early milling stage (1–6 h), the milled powder consists of Ti-based solid solution [HCP-Ti(Ni,Cu)], Ni-based solid solution [FCC-Ni(Ti,Cu)], Cu-based solid solution [FCC-Cu(Ti,Ni)], and amorphous phase (28.52 wt%). For prolonged milling time, the NiTiCu (β19) was achieved from the pre-formed phases. Moreover, microstructural parameters varied considerably with milling time; the crystallite size was found to decrease to the nanoscale range, Ti (41), Ni (21 nm), Cu (16 nm), and β19 (29 nm), while the microstrain <σ2>1/2 increased due to the deformations and defects induced during the milling process. Magnetic measurements indicated that all powders exhibited a ferromagnetic behaviour irrespective of milling time whereas the corresponding magnetic parameters were found very sensitive to the milling time. This was associated with particle size refinement in addition to the phase composition and the amount of the amorphous phase; the higher the percentage of the amorphous phase was, the lower the values of Ms and Mr. [ABSTRACT FROM AUTHOR]

The effect of Ni substitution on the magnetic properties and the critical behavior of La0.7Sr0.3Mn1−xNixO3 compounds, which were prepared by the solid-state reaction method has been investigated. Based on our investigations of the temperature and the magnetic field dependences of magnetization M(T, H) data, it is shown that the Curie temperature (TC) of La0.7Sr0.3Mn1−xNixO3 compounds will be shifted toward room temperature with increasing Ni concentration (x), TC = 359-307 K for x = 0.0-0.1. By using the modified Arrott plots and the Kouvel-Fisher methods together with M(H,T) data in the vicinity of the ferromagnetic (FM)-paramagnetic phase transition, the critical exponents (β, γ, and δ) have been determined. Our results show the existence of a short-range FM order in the undoped sample (x = 0). The values of β, γ, and δ will be shifted gradually toward those of the mean-field theory when x increases, suggesting that the long-range FM order is favored in Ni-doped samples. The results calculated on the effective exponents of βeff(ε) and γeff(ε) in the asymptotic region indicate the existence of a magnetic disorder in all the samples. [ABSTRACT FROM AUTHOR]

In this paper, an energetic coordination compound namely pentamminenitratocobalt(III) nitrate, [Co(NH 3)5(NO3)](NO3)2, was used as a new precursor for the preparation of Co3O4 nanoparticles.  e results showed that the complex is easily decomposed into the Co3O4 nanoparticles at low temperature (200 °C) without employing a surfactant or solvent and any complicated equipment.  e product was characterized by diff erential scanning calorimetry (DSC), X-ray diff raction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). Optical and magnetic properties of the product were studied by UV-visible (UV-vis) spectroscopy and a vibrating sample magnetometer (VSM), respectively. FT-IR, XRD and EDS analyses con rmed the formation of highly pure spinel-type Co3O4 phase with cubic structure. TEM images showed that the Co3O4 nanoparticles are approximately in the range of 10 to 24 nm with a mean size of around 17 nm.  e optical spectrum of the Co3O4 nanoparticles revealed the presence of two band gaps at 3.45 and 2.20 eV which are blue-shi ed relative to reported values for the bulk sample.  e magnetic measurement of the product showed a weak ferromagnetic order at room temperature. [ABSTRACT FROM AUTHOR]

Rapidly quenched (RQ) alloys RFeB ( R = Nd, Er) have been prepared by melt spinning. Their magnetic properties, structure, and phase composition have been studied before and after fast-neutron irradiation to a fluence of 1.2 × 10 n/cm. Before irradiation, it is the NdFeB-type phase (space group P4/ mnm) that is mainly present in the RQ alloys at 295 K. In the NdFeB alloy, this phase has a ferro-magnetic structure with magnetic moments at the Nd and Fe atoms oriented parallel to the c axis; the ErFeB phase found in the ErFeB alloy is characterized by a ferrimagnetic order of Er and Fe magnetic moments parallel to the basal plane. After irradiation, the crystalline state of both RQ alloys transforms into an amorphous state. The ferro- and ferrimagnetic orders are retained in them, but the Curie temperature of the alloys with Nd and Er decreases by 100 and 200 K, respectively. The spontaneous magnetization of the irradiated alloys at 5 K is approximately equal to their magnetization in the crystalline state, whereas their coercive force is lower than that for the alloys before irradiation by two orders of magnitude. The effects observed are explained by the dispersion of Fe-Fe exchange interactions resulting from the dispersion of interatomic spacings in the amorphous alloys. [ABSTRACT FROM AUTHOR]

The magnetic and structural study of GdxY1-xLaAl4 system was performed. The magnetic properties investigated in the 4–600 K temperature range and fields up to 80 kOe showed the ferromagnetic order for x≤0.8. For low gadolinium concentration, x≤0.4, the magnetic moment and the transition temperature values are lower than expected for Gd3+ ion. It is considered that the dilution allows the formation of substitutional and atomic disorder, leading to modifications in the exchange interactions and determining a random-distribution configuration for gadolinium moments. [ABSTRACT FROM AUTHOR]

The phase evolution and magnetic properties of Fe doping into REIn3 (RE = Pr, Nd, Gd, Ho) are systematically studied using X‐ray diffraction, scanning electron microscopy with energy dispersive spectrum, and magnetic measurements. Fe doping into REIn3 induces the magnetic phase transition from paramagnetic to ferromagnetic associated with minor In separation from the cubic phase with AuCu3‐type structure at room temperature. The structural stability of cubic phase is related to size effect RA and electro‐negativity difference ΔX. Cubic REIn3–xFex could be stabilized in the range of 1.0602–1.0963 Å for RA and 0.380–0.420 for ΔX. Ferromagnetism of REIn3–xFex might be explained as the 3d–3d interactions between Fe atoms and 3d–s–4f indirect interactions between Fe and rare earth atoms mediated by the conducting s electrons. The increase of magnetic moment for REIn3–xFex could result from the partial substitution of nonmagnetic element In by magnetic element Fe in the host material through dilute doping of Fe, and thus a net moment is produced. [ABSTRACT FROM AUTHOR]