The van der Waals class of materials offer an approach to two-dimensional magnetism as their spin fluctuations can be tuned upon exfoliation of layers. Moreover, it has recently been shown that ...spin-lattice coupling and long-range magnetic ordering can be modified with pressure in van der Waals materials. In this work, the magnetic properties of quasi two-dimensional CrBr3 are reported applying hydrostatic pressure. The application of pressure up to 0.844 GPa shows a 1.77% decrease in saturation magnetization with a decrease in the Curie temperature from 33.05 to 30.41 K. Density functional theory calculations with pressure up to 1 GPa show a reduction in volume and interplanar distance as pressure increases. To further understand the magnetic properties with applied pressure, the magnetocrystalline anisotropy energy (MAE) and exchange coupling parameter(s) (J) are calculated. There is small decrease in MAE and the first nearest neighbor interaction (J1) (U = 2.7 eV and J = 0.7 eV) is increasing with respect to increasing pressure. Overall, CrBr3 displays ferromagnetic interlayer coupling and the calculated exchange coupling and MAE parameters match well with the observations from the experimental work.
•Hydrostatic pressure decreases saturation magnetization and curie temperature.•Magnetocrystalline anisotropy energy decreases with increasing pressure.•Super exchange coupling increases with increasing pressure.•Pressure decreases the volume and lattice parameters of the system.•The bond angle between Cr-Br-Cr is decreasing up to 1 GPa.
The van der Waals class of materials offer an approach to two-dimensional magnetism as their spin fluctuations can be tuned upon exfoliation of layers. Moreover, it has recently been shown that ...spin-lattice coupling and long-range magnetic ordering can be modified with pressure in van der Waals materials. In this work, the magnetic properties of quasi two-dimensional CrBr3 are reported applying hydrostatic pressure. The application of pressure up to 0.844 GPa shows a 1.77% decrease in saturation magnetization with a decrease in the Curie temperature from 33.05 to 30.41 K. Density functional theory calculations with pressure up to 1 GPa show a reduction in volume and interplanar distance as pressure increases. To further understand the magnetic properties with applied pressure, the magnetocrystalline anisotropy energy (MAE) and exchange coupling parameter (J) are calculated. There is small decrease in MAE and the first nearest neighbor interaction (J1) (U = 2.7 eV and J = 0.7 eV) is increasing with respect to increasing pressure. Overall, CrBr3 displays ferromagnetic interlayer coupling and the calculated exchange coupling and MAE parameters match well with the observations from the experimental work.
This work focuses on systematic studies of Ce–Co based 1:5 permanent magnet alloys of CeCo4.4-xFexCu0.6 and CeCo3.9-xFexCu1.2 (x = 0, 0.3, 0.6, 0.9, 1.2, 1.8) by varying Co:Fe. The overarching aim of ...this manuscript is to elucidate the hard-magnetic properties through a better understanding of phase formation by the structural, microstructural, and magnetic properties in these materials. Improved mutual solubility of Fe in the 1:5 phase has been observed with an extended homogeneity range by Cu substitution. For both composition series, Fe contents of x ≤ 0.6 show a homogeneous microstructure with a single 1:5 phase and good magnetic properties. The composition region 0.6 < x ≤ 0.9 appears to be near the boundary of solubility and evolution of other phases. At x = 1.8, it is found that the homogeneous 1:5 phase and magnetic hardness deteriorated due to the evolution of secondary phases such as 2:17, 2:7, and Fe–Co. The addition of Fe improved both the magnetization and Curie temperature via increased effective exchange interactions, while an increase in Cu content enhanced coercivity.
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•Mutual solubility of the Fe content increased with the Cu content (up to x = 0.6).•Additional phases formed at high Fe contents and remained after heat treatment.•Pseudo-ternary plots provide insight into phase evolutions.•Addition of Fe improved both the magnetization and Curie temperature.•Addition of Cu improved coercivity in the alloy system.
To study the influence of soft magnetic phase coating on magnetic properties of hard/soft phase nanocomposite materials, the coating of soft magnetic FeCo on hard magnetic SmCo sub(5) nanochips was ...performed via a sonochemical process. First, anisotropic hard magnetic SmCo sub(5) nanochips were prepared by surfactant-assisted high-energy ball milling in the presence of oleic acid as a surfactant and heptane as a solvent. Then, the soft magnetic FeCo was coated on SmCo sub(5) nanochips by the reduction of FeCl sub(3) and CoCl sub(2) with hydrazine using ultrasonic waves in the presence of NaOH. The amount of the soft phase coating on the hard magnetic nanochips was controlled by varying the initial ratio of soft-phase precursors to hard magnetic particles during the reaction. The soft-phase coating on the hard phase chips has lead to an enhanced remanence due to an exchange coupling between the soft and the hard magnetic phases at optimal hard/soft phase ratios. The composite chips also show a strong magnetic anisotropy when aligned in a magnetic field. The anisotropic SmCo sub(5)/FeCo core/shell nanocomposite chips are promising candidates as building blocks for high-performance anisotropic nanocomposite bonded or fully dense magnets via a bottom-up fabrication approach.
To study the influence of soft magnetic phase coating on magnetic properties of hard/soft phase nanocomposite materials, the coating of soft magnetic FeCo on hard magnetic SmCo 5 nanochips was ...performed via a sonochemical process. First, anisotropic hard magnetic SmCo 5 nanochips were prepared by surfactant-assisted high-energy ball milling in the presence of oleic acid as a surfactant and heptane as a solvent. Then, the soft magnetic FeCo was coated on SmCo 5 nanochips by the reduction of FeCl 3 and CoCl 2 with hydrazine using ultrasonic waves in the presence of NaOH. The amount of the soft phase coating on the hard magnetic nanochips was controlled by varying the initial ratio of soft-phase precursors to hard magnetic particles during the reaction. The soft-phase coating on the hard phase chips has lead to an enhanced remanence due to an exchange coupling between the soft and the hard magnetic phases at optimal hard/soft phase ratios. The composite chips also show a strong magnetic anisotropy when aligned in a magnetic field. The anisotropic SmCo 5 /FeCo core/shell nanocomposite chips are promising candidates as building blocks for high-performance anisotropic nanocomposite bonded or fully dense magnets via a bottom-up fabrication approach.
In the recent past, heterostructures of magnetic oxide thin films have attracted a great deal of research excitement due to very interesting physical properties such as antiferromagnetic interlayer ...coupling, tunable exchange-bias, interfacial driven magnetic properties and high mobility electron gas across the interfaces. In this work, we report on the comprehensive magnetic properties observed from the heterostructures of (2 unit cells) La0.7Sr0.3CrO3/(8 unit cells) La0.7Sr0.3MnO3/(2 unit cells) La0.7Sr0.3CrO3, which are epitaxially deposited on SrTiO3 substrate by plasma-assisted oxide molecular beam epitaxy. Using SQUID magnetometer, the magnetic properties are studied when the magnetic field was applied both in plane and out of plane. The Curie temperature of this structure is found to be at 290 K. Most significantly, at 2 K, we observed a complete up/down shift (along magnetization axis) of hysteresis loop when the sample was cooled under a magnetic field of ± 5000 Oe in the in-plane configuration. We believe that the strong antiferromagnetic (super) exchange coupling of Mn-Cr across the two interfaces is responsible for the observed exchange bias. We will present and discuss our in-detailed experimental findings collected on this heterostructure as a function of temperature and magnetic field.
Ferromagnetic CoNi nanocrystals with different shape and size were synthesized by reduction in liquid polyol via heterogeneous nucleation. Morphological, structural and compositional ...characterizations of the nanocrystals were performed together with magnetic property measurements. The CoNi nanocrystals can be controlled to form nanowires or nanorods with length of 20-200 nm and diameter of 5-20 nm by using different catalyst concentration in the synthesis. It is found that the magnetic coercivity of the CoNi nanowires/ nanorods depends on the morphology. The highest coercive force of 2.9 kOe was obtained for nanowires of 50 × 200 nm with Co 80 Ni 20 composition.
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