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A Z1-type Fe 3 Pd alloy with negative enthalpy of formation at ambient pressure has been discovered recently, however, its physical properties under high pressures remain unclear. In this work, the effect of pressure on the magnetic, electronic, lattice dynamic, mechanical and thermal properties of the Z1-Fe 3 Pd are investigated thoroughly by the first-principles methods. Under high pressures, the Z1-Fe 3 Pd are energetically favorable compared to other types Fe 3 Pd structures. A pressure-induced magnetic phase transition from ferromagnetic (FM) to ferrimagnetic (FIM) state are found, and the FM and FIM states are dynamically and mechanically stable under high pressures. The electronic density of states for both the FM and FIM states are analyzed to understand their magnetism. These two magnetic configurations are ductile, but their elastic properties and anisotropy are quite different. Additionally, the FM and FIM states have high uniaxial magnetocrystalline anisotropy, the FM state is a semi-hard magnet, and the FIM state undergoes a transition from hard magnet to semi-hard magnet with pressure. Finally, the volume and linear thermal expansion coefficients under high pressure are calculated, and the anisotropy of thermal expansion is also discussed in detail. • A stable Fe 3 Pd structure under high pressure is discovered for the first time. • The pressure-induced magnetic phase transition from ferromagnetic to ferrimagnetic state is determined. • The structural stability is verified by formation enthalpy, phonon and elastic. • Elasticity, thermal expansion and their anisotropies are investigated. • Ferrimagnetic state transforms from a hard magnet to a semi-hard magnet under high pressure. [ABSTRACT FROM AUTHOR]

The effects of Fe substitution on the structural and magnetic properties of the HoCo 12- x Fe x B 6 (0 ≤ x ≤ 2) series of intermetallic compounds have been studied. All of the compounds form in the rhombohedral SrNi 12 B 6 -type structure, the lattice constants increasing linearly with x. These compounds are ferrimagnets with a small transition metal magnetic moment and exhibit a spin reorientation transition. The Curie temperature decreases from 147 K for x = 0–105 K for x = 2. The Fe for Co substitution leads also to a progressive decrease of the spontaneous magnetization. The spin reorientation transition temperature is significantly reduced upon Fe for Co substitution whereas the compensation temperature is much less sensitive to the Fe composition. • Ferrimagnetic ground state. • Compensation point. • Spin reorientation transition. • Magnetocrystalline anisotropy. • Monotonic decrease of T C , T SR and M S upon Fe for Co substitution. [ABSTRACT FROM AUTHOR]

Crystal structure, magnetostriction, magnetic and magnetothermal properties have been studied for novel non-stoichiometric ErFe 2 Mn x (0 ≤ x ≤ 0.6) compounds. It has been found that for х ≤ 0.4 the compounds crystallize with MgCu 2 -type structure. Curie temperature and magnetic moment values decrease with manganese alloying. Molecular field coefficients have been calculated within ferrimagnetic two-sublattice molecular field model. Magnetic and heat capacity measurements have been used to calculate magnetocaloric effect in a wide temperature range. It has been demonstrated that increasing the Mn content in ErFe 2 Mn x leads to a significant increase (up to 39 %) of anisotropic magnetostriction value at 77 K in magnetic field of 18 kOe. At the same time, the value of effective magnetocrystalline anisotropy decreases. Thus, manganese alloying opens new way for tuning magnetocrystalline anisotropy and magnetostriction in Laves phase compounds. [Display omitted] • single phase non-stoichiometric ErFe 2 Mn х compounds are formed up to Mn concentration x = 0.4. • ErFe 2 Mn х compounds with x ≤ 0.2 have the compensation temperatures at М (Т) curves. • Curie temperature and magnetic moment values decrease with manganese alloying. • The value of anisotropic magnetostriction significant increase with increasing the Mn content. • The value of effective magnetocrystalline anisotropy decreases with increasing the Mn content. [ABSTRACT FROM AUTHOR]

The band alignment, intrinsic ferromagnetism, Dzyaloshinskii-Moriya interaction, magnetic anisotropy and critical temperature (T C) of a GdI 2 /GeC van der Waals (vdW) heterostructure were systematically investigated by first-principles calculations and Monte Carlo simulations. The proposed GdI 2 /GeC vdW heterostructure is a bipolar magnetic semiconductor with Type-I band alignment, large in-plane magnetic anisotropy energy (MAE) of − 0.912 mJ/m2 and high critical temperature of 466 K. In addition, under biaxial strains, the heterostructure transformed from semiconductor into metal, while the easy magnetization axis maintained in-plane and T C increased. The results indicated that the GdI 2 /GeC vdW heterostructure presented large MAE and high T C , having potential applications in spintronic devices. [Display omitted] ● The heterostructures is a bipolar magnetic semiconductor. ● The heterostructures with large in-plane magnetic anisotropy. ● The heterostructures with high critical temperature 466 K. [ABSTRACT FROM AUTHOR]

Co(Fe 1 -x Cr x) 2 O 4 (x = 0.02, 0.10, 0.15, 0.30, 0.50) samples are synthesized by the sol-gel method. The XRD patterns and subsequent Rietveld refinement provided structural analysis and confirmation of the samples' single-phase formation. XPS measurement reveals the existence of the elements Co, Cr and Fe in 2+ and 3+ oxidation states. The saturation magnetization (M s), coercivity (H c) and magnetocrystalline anisotropy (K 1) are observed to decline to as low as 10 emu/g, 35 Oe and 0.50 (106 erg/cm3) following Cr substitution, which indicated that the samples transform to a soft magnetic material. Cr substitution also lowers the ferrimagnetic (FiM) to paramagnetic (PM) transition temperature, T c , from 752 K for x = 0.02 to 307 K for x = 0.50. With Cr replacement, the dielectric constant and dielectric loss values decrease, indicating it to be a potential contender for high frequency applications. The dielectric constant for x = 0.30 and x = 0.50 samples rises sharply around 1 MHz owing to the LC resonance effect between the samples and the measurement leads. The ac conductivity plots are found to be in conformity with Jonscher's single power law, and the conduction process is revealed to be attributable to the small polaron hopping mechanism. • Cr substituted Cobalt ferrites has been synthesized in single phase form by sol-gel method. • Co, Cr and Fe exists only in 2+ and 3+ oxidation state. • Cr occupies only the octahedral sites. • Saturation magnetization, Coercivity and magnetocrystalline anisotropy are observed to decline following Cr substitution. • Dielectric constant and dielectric loss decreases with Cr substitution. [ABSTRACT FROM AUTHOR]

Di-phase ferroelectric-ferrite composites with the same composition close to the percolation limit (0.66BaTiO 3 -0.33CoFe 2 O 4) and with different phase arrangements (randomly mixed phases and tri-layer structures) have been consolidated by using spark plasma sintering and their properties were comparatively analyzed. The intrinsic effective dielectric constant has been estimated by using finite element method and a value almost ten times higher was predicted for the randomly mixed composite, as result of different field distributions inside the ferrite and ferroelectric phases. At room temperature, experimental permittivity contains an intrinsic behavior overlapped onto a very strong extrinsic component determined by the interfaces and by local charge inhomogeneity. The extrinsic dielectric behavior has been discussed in terms of thermally activated relaxation mechanisms developed in both types of investigated structures, as revealed by the temperature-dependence impedance spectroscopy. The magnetic properties are derived as "sum property" from the ferrimagnetic character of CoFe 2 O 4 and show the lowest magnetization for the randomly mixed composites and a weak magnetic anisotropy when the magnetic field was applied in-plane or out-of-plane in the layered structure. Due to the different levels of interface doping specific to the different types of interfaces, the magnetic Curie temperature of the two composites ranges from 720 K in the randomly mixed structure to 746 K for the layered one. The ferroelectric P (E) loops and a modest ME coefficient of 14 mVOe−1cm−1 at 100 Hz were determined only for the layered structure, due to the high leakage and to the small grain size (below 200 nm) in the ferroelectric BaTiO 3 component. • Randomly mixed and tri-layered structure composites were comparatively investigated. • Role of the phase arrangement on the dielectric properties was predicted by FEM. • Experimental dielectric data contains a strong influence from extrinsic phenomena. • Magnetic properties slightly depend on the phase arrangement. [ABSTRACT FROM AUTHOR]

Abstract The nanocrystalline Cd 0.5-X Ni X Co 0.5 Fe 2 O 4 (x = 0.0 to 0.5) ferrites were synthesized by auto combustion technique using hexamine as fuel. The substitution of non magnetic Cd2+ ions in the tetrahedral site causes canting on the octahedral site. The saturation magnetization increases with Ni substitution up to X = 0.3 and then decreases with further increase in Ni substitution at room temperature. This behaviour is consistent with Yafet–Kittel magnetic ordering. A three sub-lattices model (A, B 1 and B 2) has been used to describe the magnetic behaviour of the ferrites. Low temperature unsaturated magnetization behaviour indicates the core shell structure of the nanoparticles i:e ordered core spins and randomly oriented surface spins. Reduced remanent magnetization values (Mr/Ms) suggest that the samples have uniaxial anisotropy at room temperature. The variation of magnetizations of the samples with temperature was studied by ZFC–FC technique at three different applied fields of 250 Oe, 500 Oe and 1000 Oe. The nature of the curves showed a change with increase in Ni concentration. The blocking temperature and anisotropy increased with Ni concentration. The average crystallite size was found to be in the range of 6–13 nm. The lattice constant decreased with Ni concentration. The Dielectric property has been explained on the basis of Maxwell-Wagner's two layer model while A.C. susceptibility studies indicate single domain-superparamagnetic domain structure. The Curie temperature shifts to higher temperature with increase in Ni concentration. Highlights • Fuel deficient hexamine to metal nitrates ratio. • Spin canting with increase in Cd concentration. • Change in the shapes of the MT curves with Ni substitution. • Uniaxial anisotropy at room temperature. • Core-shell spin model of magnetization. [ABSTRACT FROM AUTHOR]

In 3 d − 4 f intermetallic compounds, a Co substitution for Fe usually strengthens the exchange interactions due to a shift of the Fermi energy to a region of the 3 d band with higher density of states. Here, we study the influence of Co on the magnetism of ferrimagnetic DyFe 5 Al 7 using magnetization measurements in static (up to 14 T) and pulsed (up to 58 T) magnetic fields. We find that the homogeneity range of DyFe 5− x Co x Al 7 is limited to x ≤ 2.5 . The Co substitution for Fe produces a strong detrimental effect on the 3 d − 3 d intrasublattice exchange interactions, which leads to a pronounced decrease of the Curie temperature and of the 3 d − 4 f intersublattice exchange field. A reduction of the density of states at the Fermi level might occur due to a broadening of the 3 d band. A decrease of the rare-earth contribution to the magnetic anisotropy energy is also observed with increasing Co content. This is attributed to a competition between the Fe and Co contributions to the crystal electric field at the Dy site. [ABSTRACT FROM AUTHOR]

The magnetic structure of La 1- x Tb x Mn 2 Si 2 compounds with 0 ≤ x ≤ 1 has been studied by powder neutron diffraction and magnetization measurements on single-crystal samples. We demonstrate that at 4.2 K, with increasing the Tb concentration, a canted ferromagnetic structure of LaMn 2 Si 2 changes at x > 0.2 to a canted antiferromagnetic structure. The antiferromagnetic in-plane component of Mn moment decreases with increasing concentration x and vanishes at x > 0.5. TbMn 2 Si 2 is characterized by a collinear in-plane Mn ordering and ferrimagnetic structure, in which the Mn sublattice possesses the ferromagnetic interlayer alignment along the easy c -axis. Neutron diffraction study does not reveal a long-range magnetic order of Tb moments for the compounds with x ≤ 0.4. Our results show that for concentrations 0.2 < x ≤ 0.4, a competition of the interlayer Tb-Mn, Mn-Mn exchange interactions and strong uniaxial magnetic anisotropy leads to formation of a frustrated magnetic state of Tb ions, which prevents magnetic ordering in the Tb sublattice. [ABSTRACT FROM AUTHOR]

• The mechanical alloying reduced the sintering temperature to stabilize orthorhombic phase. • The site occupancy of Fe and Ga ions controlled ferrimagnetism, soft and hard magnetic phases. • The low temperature magnetic peak appeared due to magnetic frustration and anisotropy. • The extra moment with reference to spin value suggested contribution for orbital moment. • The ferrimagnetism and spin-phonon coupling indicated multiferroelectric nature in the system. A combined technique of mechanical alloying and heat treatment has been used to prepare the polycrystalline samples of Fe 2−x Ga x O 3 (x = 0.6–1.2) system in orthorhombic phase. It has been possible to reduce the sintering temperature by ~350 °C for stabilizing the orthorhombic phase in comparison to the temperature reported in literature. The Rietveld refinement of X-ray diffraction patterns indicated the distribution of Ga and Fe atoms in the Ga1, Ga2, Fe1 and Fe2 sites of the lattice structure. A linear variation of the lattice parameters with Ga/Fe content showed application of Vegard's law. The temperature-dependent magnetization measurements confirmed ferrimagnetic order of Fe spin moments. The ferrimagnetic transition temperature (T C) has decreased from 320 K to 100 K with the increase of Ga content in the range of x = 0.6–1.2. Temperature-dependent Raman spectroscopy data ruled out any structural phase transition at T C , but an anomalous behaviour of the position and width of the peaks of Raman active phonon modes near to T C confirmed a strong spin–phonon coupling in the material. The spin–phonon coupling strength (η) for the A9 mode has been found around 1.64 cm−1 for x = 1 and 3.34 cm−1 for x = 0.8, and η for the A21 mode has been found around 2.12 cm−1 for x = 1 and 3.28 cm−1 for x = 0.8. The spin-phonon coupling strength has been diluted in the samples with higher content of Ga. The experimental results indicated that the variation of Ga/Fe content and its distribution in lattice sites determine the ferrimagnetic properties, magnetic anisotropy and spin-phonon coupling in Fe 2−x Ga x O 3 system. The results are expected to be useful for understanding the spin-phonon coupling in multiferroic-magnetoelectric materials with magnetic and electric transitions near to room temperature. [ABSTRACT FROM AUTHOR]

Tunability of structural and magnetic properties of Mn 3- x Co x Ga films is presented by Co substitution, where critical behavior emerges 0.37 ≤ x ≤ 0.56 exhibiting a transition from tetragonal hard ferrimagnetic with perpendicular magnetic anisotropy (PMA) to a cubic soft ferrimagnetic phase with in-plane magnetic anisotropy (IMA). In the critical regime, coexisting state of tetragonal and cubic phases possesses significantly low coercive field (H C = 1.9 kOe) with relatively low saturation magnetization (M S = 100~150 emu/cc) while maintaining the PMA. From first-principles calculations, moments of two Mn sites do not change upon Co substitution. However, moments of substituted Co almost vanish in tetragonal while giving around 1 μ B in cubic phase, which agrees with overall M S behaviors of the experimental results. These findings not only uncover the hidden magnetic state in Mn 3- x Co x Ga by altering the parallel and antiparallel coupling between Mn and Co, but also provide an additional degree of freedom for spintronic applications using Mn-based Heusler compounds. • Critical regime during the transition from hard ferrimagnetic tetragonal to soft ferrimagnetic cubic in Co-substituted Mn3Ga. • Dramatic reduction of the coercive field on remaining perpendicular magnetic anisotropy in the critical regime. • Compensation point near this critical regime due to a large reduction of the Co moments when substituted in Mn 3 Ga. [ABSTRACT FROM AUTHOR]

NiCr 2 O 4 nanoparticles have been successfully prepared by chemical co-precipitation method. Desired crystallographic phase of NiCr 2 O 4 is confirmed by analyzing x-ray diffractrograms. With increasing annealing temperature, crystal transition from cubic to tetragonal phase is observed. The increasing average particle size from ∼80 to ∼280 nm is studied by SEM and TEM micrographs as annealing temperature increases. Exchange bias behavior is detected at 10 K accompanied by the shift of magnetic hysteresis loops along field axis. This effect is gradually weakening as annealing temperature increases. The magnetization depending on temperature under zero-field-cooled and field-cooled conditions suggests the ferrimagnetic transition at ∼72 K and the spiral magnetic order at ∼25 K. Furthermore, the ferrimagnetic transition point shifts slightly to low temperature with increasing annealing temperature. Based on the measurement results, the appearance and evolution of exchange bias effect in NiCr 2 O 4 nanoparticles with improving annealing temperature should be simultaneously derived from the lattice transition and the surface spin effects. • Annealing temperature evidently affects the microstructure and magnetism of NiCr 2 O 4 nanoparticles. • Increasing annealing temperature results in crystal transition from cubic to tetragonal phase. • Increasing average particle size from ∼80 to ∼280 nm is observed as annealing temperature increases. • Magnetic behavior is regulated by crystal transition and particle size due to annealing temperature. [ABSTRACT FROM AUTHOR]