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Direct synthesis of ultrasmall and stable magnetite nanoparticles coated with one single carbon layer for sensitive surface-enhanced Raman scattering
摘要： Ultrasmall spherical magnetite nanoparticles (Fe3O4 NPs) coated with one single carbon layer (Fe3O4@1C NPs) were directly synthesized by a simple, fast one-step hydrothermal reaction at low temperature (200℃). The as-synthesized Fe3O4@1C NPs were easily separated and purified from the resultant mixture, without the need for any additional energy input and chemicals. The as-purified Fe3O4@1C NPs not only displayed typical superparamagnetic behavior but also exhibited quite good long-term stability after being exposed to the open air under the room conditions for more than 2 months. Importantly, the long-term stored Fe3O4@1C NPs exhibited a highly sensitive surface-enhanced Raman spectroscopy (SERS) response toward Rhodamine-b (RdB) molecules with low concentration. The multifunctional and recyclable Fe3O4@1C NPs presented a prospective application for the selective enrichment and sensitive SERS detection of chemical and biomolecular assays.
关键词： coated with one single carbon layer (Fe3O4@1C NPs),Dehydration reaction,Saturation magnetization,Long-term stability,Magnetite nanoparticles (Fe3O4 NPs)
更新于2025-11-14 17:03:37
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[Advances in Intelligent Systems and Computing] Information Systems Design and Intelligent Applications Volume 862 (Proceedings of Fifth International Conference INDIA 2018 Volume 1) || Study of Electrical and Magnetic Properties of Multiferroic Composite (BiFeO3)x(Ba5RTi3V7O30)1?x
摘要： Polycrystalline Samples of the composite (BiFeO3)x(Ba5RTi3V2O30)1?x (R––Rare Earth Element) is prepared by high-temperature Solid-State Reaction Technique. The formation of the material has been con?rmed through XRD (X-ray Diffractometer) to ensure the single-phase formation. Dielectric characterization has been done by Impedance Analyser (HIOKI-IM3536) to study the variation of dielectric constant with frequency and temperature in a wide range to see the dielectric anomaly. Magnetization study is also done by Vibration Magnetometer for different values of x in the composite (BiFeO3)x(Ba5RTi3V2O30)1?x.
关键词： Dielectric,XRD,Impedance analyzer,magnetization,Neel temperature
更新于2025-09-23 15:23:52
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The finite size effect on the transport and magnetic properties of epitaxial Fe <sub/>3</sub> O <sub/>4</sub> thin films
摘要： Magnetite (Fe3O4) has great potential for use in the new field of spintronics due to its interesting physical properties, e.g., half-metallic ferromagnetic nature and metal–insulator transition (Verwey transition). Therefore, a basic understanding of these properties is essential for applications in spintronics devices, especially as the film thickness is reduced. In this work, the transport and magnetic properties of stoichiometric ultra-thin epitaxial Fe3O4 films have been investigated. The Fe3O4 films were grown on MgO (001) substrates using molecular beam epitaxy under optimal growth conditions. Low energy electron diffraction and X-ray photoemission spectroscopy confirmed that the films are single phase Fe3O4. The Verwey transition has been investigated using both transport and magnetization measurements. The magnetization measurements show a sharp Verwey transition in all of these films, which indicates that the films have properties comparable to the bulk. Furthermore, the magnetization measurements at room temperature show that the ultrathin films with thickness t < 20 nm are ferromagnetic with magnetization values greater than those for bulk magnetite. Such enhanced magnetization in ultrathin Fe3O4 films is very promising for spin injection and other applications.
关键词： Verwey Transition,Epitaxial Growth,Magnetization,Fe3O4,Thin Film
更新于2025-09-23 15:23:52
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Tattoo Inks EM Characterization for MRI Interaction Evaluation
摘要： The lack of knowledge about the safety implications of tattooed individuals subjected to Magnetic Resonance Imaging (MRI) may, sometimes, lead to an exaggerate reaction from physicians such as the avoidance of the exam for tattooed patients. To explore the actual risks, in this work, the magnetic and electrical properties of five different tattoo inks have been measured to investigate their interaction with the MRI electromagnetic (EM) fields. Results highlight that the magnetic and electrical behaviour strongly depend on the type of analyzed ink. Magnetic measurements also reveal a different response between the ink solutions and the relative pigments.
关键词： Magnetic Resonance Imaging,electrochemical impedance,magnetization measurements,tattoo ink,Electrical conductivity,tattoo pigment
更新于2025-09-23 15:23:52
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Room-temperature ferromagnetism and morphology evolution of SnO2 flower-like microparticles by Zn-doping
摘要： We report on the growth of undoped and Zn-doped flower-like microparticles, which are constituted of SnO2 acicular nanoparticles (NPs) aggregated by one of their ends. NPs were synthesized by the hydrothermal method. The morphology of the NPs progressively changes from truncated rods to sharp needles by the effect of Zn doping. This morphology evolution is attributed to an increase of the surface free energy of the NPs' facets and to a modification of the growth front direction. Undoped samples exhibit a very low magnetization attributed to single positive charged oxygen vacancies, while Zn-doped samples exhibit ferromagnetic ordering due to Zn atoms in Sn substitutional positions (ZnSn). Thermal treatment under reducing atmosphere leads to the creation of an excess of VO conducting to a reduction of the magnetization, demonstrating that ferromagnetism in Zn-doped SnO2 NPs is attributed to ZnSn defects and to the octahedrally coordinated oxygen atoms.
关键词： Magnetization,Oxygen vacancies,SnO2 nanoparticles,Morphology,Zn-doped
更新于2025-09-23 15:22:29
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Tunable Spin Seebeck Diode with Magnonic Spin Tunneling Junction
摘要： We theoretically investigate the spin–wave spin current induced by the spin Seebeck effect in magnonic spin tunneling junctions (MSTJs) for arbitrary magnetization directions. We show that the MSTJ functions as a tunable spin Seebeck diode in which the tunneling spin current can be turned on and off with high efficiency by controlling the magnetization direction.
关键词： spin current,spin Seebeck effect,diode,magnetization direction,magnonic spin tunneling junction
更新于2025-09-23 15:22:29
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Influence of magnetic field orientation on laser-induced magnetization precession in Ni-Mn-Sn Heusler alloy film
摘要： Laser-induced magnetization precession is investigated in Ni-Mn-Sn Heulser alloy film using pump-probe all-optical technique. The studies are performed as a function of external magnetic field H applied at various angles with respect to the sample normal. Strong dependence of precession parameters, frequency f, amplitude A and effective damping, two precession modes, identified as Damon-Eshbach (DE) and first-order standing spin wave (PSSW) modes were observed. The values of wave vector for DE mode have been determined. The experimentally obtained exponentially decayed. The dependencies of the magnetization precession parameters have been well simulated in the frame of phenomenological approach, based on Landau-Lifshitz-Gilbert equation.
关键词： standing spin wave mode,pump-probe all-optical technique,Landau-Lifshitz-Gilbert equation,Ni-Mn-Sn Heusler alloy,Damon-Eshbach mode,Laser-induced magnetization precession
更新于2025-09-23 15:21:01
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Terahertz Emission From an Exchange-Coupled Synthetic Antiferromagnet
摘要： We report on terahertz emission from Fe-Mn-Pt/Ru/Fe-Mn-Pt and Pt/Co-Fe-B/Ru/Co-Fe-B/Pt synthetic antiferromagnet (SAF) structures upon irradiation by a femtosecond laser; the former is via the anomalous Hall effect, whereas the latter is through the inverse spin Hall effect. The antiparallel alignment of the two ferromagnetic layers leads to a terahertz emission peak amplitude that is almost double that of a corresponding single-layer or bilayer emitter with the same equivalent thickness. In addition, we demonstrate by both simulation and experiment that terahertz emission provides a powerful tool to probe the magnetization reversal processes of individual ferromagnetic layers in a SAF structure, as the terahertz signal is proportional to the vector difference (M1 ? M2) of the magnetizations of the two ferromagnetic layers.
关键词： anomalous Hall effect,synthetic antiferromagnet,terahertz emission,magnetization reversal,inverse spin Hall effect
更新于2025-09-23 15:21:01
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Study the electronic properties and magnetization of rutile polymorph CoxTi1-xO2 super cell at various cobalt (Co) concentrations using first principle calculation
摘要： First principle calculation has been performed to study the electronic properties and magnetization of CoxTi1-xO2 at different cobalt concentration. Equilibrium lattice constant of CoxTi1-xO2 at 0.0% cobalt concentration was obtained about 4.81?. The obtained value is slightly larger than the experimental value. The calculated band gap of CoxTi1-xO2 at 0.0% cobalt concentration is 3.0 eV which consistent with other reports. The calculated band gap for 16.6% is 0.5 eV, for 33.3% is 0.1 eV and for 50.0% is approximately 0.0 eV. The calculated band gap of CoxTi1-xO2 decreased with increased cobalt concentration. On the other hand at 0.0% cobalt concentration, the magnetization is zero and at 50.0% cobalt concentration, magnetization is 3.36 Bohr mag/cell. The density of states calculation for spins up and spins down are symmetric at 16.6% and 33.3% cobalt concentration. At 50.0% cobalt concentration the density of states shows asymmetric for spin up and spin down which indicates the ferromagnetic nature.
关键词： Band structure,Magnetization,Equilibrium lattice constant,Density function theory (DFT),Density of State (DOS)
更新于2025-09-23 15:21:01
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Modulation of the properties of dinuclear lanthanide complexes through utilizing different ?2-diketonate co-ligands: near-infrared luminescence and magnetization dynamics
摘要： A family of new dinuclear lanthanide complexes as the simplest entities showing intramolecular magnetic interactions, [Ln2(dbm)2(L)2(CH3OH)2] (Ln = Tb (1), Dy (2), Ho (3), Er (4), Yb (5), Lu (6)), [Ln2(acac)2(L)2(EtOH)2] (Ln = Dy (7), Er (8)), [Dy2(TTA)2(L)2(CH3OH)2]·2CH2Cl2 (9) and [Dy2(tfa)2(L)2(CH3OH)2] (10) (H2L = N’-(2-hydroxy-5-methylphenyl)-pyrazine-2-carbohydrazide, Hdbm = 1,3-diphenyl-1,3-propanedione, Hacac = acetylacetone, HTTA = 2-thenoyltrifluoroacetone, Htfa = trifluoroacetylacetone), were constructed successfully by the reaction of a Schiff base ligand H2L and four different β-diketonate salts. As for complexes 4, 5 and 8, all exhibit the characteristic emission peaks of the corresponding Er3+, Yb3+ and Er3+ ions, respectively. Meanwhile, the excitation wavelength (510 nm) of 5 is located in the visible region, confirming its significant potential application value. Magnetic studies indicate that complexes 9 and 10 exhibit characteristic slow relaxation of magnetization with the energy barriers (Ueff) of 102 K for 9 and 140 K for 10 under a zero dc field. Under the optimized dc fields, slow magnetic relaxations are present in 2 and 7, and the Ueff values of 9 and 10 have been improved. This proves that the β-diketonate co-ligands deserve an important role in regulating Dy-SMMs influenced by the diverse perturbations of the axial crystal field originating from minor changes in the coordination environment.
关键词： single-molecule magnets,dinuclear lanthanide complexes,β-diketonate co-ligands,near-infrared luminescence,magnetization dynamics
更新于2025-09-23 15:19:57