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In the past few decades, a development of organic magnets with room-temperature strong ferromagnetism is challenged by the difficulty of creating three-dimensional (3D) long-range magnetic orderings in organic materials at a temperature higher than room temperature. Here, we report room-temperature ferrimagnetism of a tetragonal organic–inorganic hybrid Fe14Se16(tepa)III (tepa = tetraethylenepentamine), where III represents a coordination of a tepa molecule with a Fe3+ ion for an organic complex. The layered hybrid in a nanoplate-like shape is formed by periodic incorporation of tetragonal β-Fe3Se4 inorganic layers and organic spacing layers consisting of tepa and Fe3+. Fe14Se16(tepa)III shows a saturation magnetization MS of 7.2 emu g−1 at 300 K and a record-high Néel temperature TN (>560 K) in the organic magnets reported experimentally. A Mössbauer spectrum confirms a 3D long-range magnetic ordering of Fe2+ [S = 2 (71.4%)] and Fe3+ ions [S = 5/2 (21.7%) and 1/2 (4.0%)] in β-Fe3Se4 layers and organic spacing layers of Fe14Se16(tepa)III,9. First-principles calculations explain that the 3D long-range antiferromagnetic interactions between interlayer and intralayer irons result in the strong ferrimagnetism of Fe14Se16(tepa)III. This study unveils the possibility of tuning magnetic couplings of interlayer and intralayer high-spin Fe3+ and Fe2+ for enhancing the ferrimagnetism of layered hybrids and, thus, for future room-temperature magnetic/spintronic applications. [ABSTRACT FROM AUTHOR]

Graphene (Gr) and hexagonal boron nitride (hBN) nanoribbons have shown significant potential for various applications owing to their unique electronic and magnetic properties. This study explored the effects of hydrogenation on the magnetic and electronic properties of Gr-hBN nanoribbons (Gr/BNNRs). The influence of hydrogenation of one or both edges, i.e., Gr edge and B or N edge, combined with different interface types, on the magnetic ordering and occurrence of half-metallicity in Gr/BNNRs was investigated using spin-polarized density functional theory. The findings reveal that hydrogenation induces ferromagnetism or ferrimagnetism, depending on the edge and interface configuration, and leads to half-metallicity in several configurations. These properties suggest Gr/BNNRs as promising materials for spintronic devices, where the ability to control magnetic ordering and electronic behavior via edge hydrogenation could be pivotal. The results highlight the potential for fine-tuning magnetic and electronic properties in Gr/BNNRs, paving the way for their application in advanced spin-based technologies. [ABSTRACT FROM AUTHOR]

Using the double-time Green’s function method in combination with the random phase approximation and Anderson–Callen approximation, we investigate the magnetic properties of the ferrimagnetic Heisenberg model on a decorated square lattice. The effects of nearest-neighbor interactions and single-ion anisotropy on the compensation temperature are explored. Our results indicate that the next-nearest-neighbor interaction and/or single-ion anisotropy are not a necessary condition of the appearance of compensation temperature. When considering only the nearest-neighbor interaction, the system can also exhibit a compensation temperature. By comparing the impact of the nearest-neighbor interaction and single-ion anisotropy on the sublattice magnetizations of the system, a general condition of the appearance of compensation temperature is claimed. [ABSTRACT FROM AUTHOR]

Through a combination of magnetic susceptibility, specific heat, and neutron powder diffraction measurements we have revealed a sequence of four magnetic phase transitions in the columnar quadruple perovskite Er2CuMnMn4O12. A key feature of the quadruple perovskite structural framework is the complex interplay of multiple magnetic sublattices via frustrated exchange topologies and competing magnetic anisotropies. It is shown that in Er2CuMnMn4O12, this phenomenology gives rise to multiple spin‐reorientation transitions driven by the competition of easy‐axis single ion anisotropy and the Dzyaloshinskii–Moriya interaction; both within the manganese B‐site sublattice. At low temperature, one Er sublattice orders due to a finite f‐d exchange field aligned parallel to its Ising axis, while the other Er sublattice remains non‐magnetic until a final, symmetry‐breaking phase transition into the ground state. This non‐trivial low‐temperature interplay of transition metal and rare‐earth sublattices, as well as an observed k = (0, 0, ½) periodicity in both manganese spin canting and Er ordering, raises future challenges to develop a complete understanding of the R2CuMnMn4O12 family. [ABSTRACT FROM AUTHOR]

Through a combination of magnetic susceptibility, specific heat, and neutron powder diffraction measurements we have revealed a sequence of four magnetic phase transitions in the columnar quadruple perovskite Er2CuMnMn4O12. A key feature of the quadruple perovskite structural framework is the complex interplay of multiple magnetic sublattices via frustrated exchange topologies and competing magnetic anisotropies. It is shown that in Er2CuMnMn4O12, this phenomenology gives rise to multiple spin‐reorientation transitions driven by the competition of easy‐axis single ion anisotropy and the Dzyaloshinskii–Moriya interaction; both within the manganese B‐site sublattice. At low temperature, one Er sublattice orders due to a finite f‐d exchange field aligned parallel to its Ising axis, while the other Er sublattice remains non‐magnetic until a final, symmetry‐breaking phase transition into the ground state. This non‐trivial low‐temperature interplay of transition metal and rare‐earth sublattices, as well as an observed k = (0, 0, ½) periodicity in both manganese spin canting and Er ordering, raises future challenges to develop a complete understanding of the R2CuMnMn4O12 family. [ABSTRACT FROM AUTHOR]

We attempt to study the mixed-spin Ising on two decorated ferrimagnetic ternary metallic nanoislands possessing hexagonal and square structures, with a mixture of spin numbers 3/2, 1, and 1/2. Via the finite cluster approximation, the critical and compensation characteristics have been explored by implementing the influences of decorating and interface exchange couplings ( J 1 , J 2 ), along with the crystal fields ( D σ , D S ) on the phase diagrams and magnetizations. In the absence of crystal fields, the hexagonal structure exhibits only the second-order transition with one or two compensation points; meanwhile, the square structure undergoes the multiple transitions behavior (two or three transition temperatures) with a first-order transition at low temperatures. The inclusion of the crystal fields demonstrates the elevation of the ferrimagnetic region of order. Interestingly, we have uncovered under only the effect of D S acting on spin-1 sublattice the occurrence of the first-order with reentrance indicating two and three transitions for the hexagonal and square structures, respectively. Finally, under a uniform crystal field ( D σ = D S = D), the first-order keeps existing only for the square nanoisland. [ABSTRACT FROM AUTHOR]

This investigation focused on the fabrication of ceramic ferrimagnetic CuFe2O4–conductive polypyrrole (PPy) composites for energy storage. CuFe2O4 with a crystal size of 20–30 nm and saturation magnetization of 31.4 emu g−1 was prepared by hydrothermal synthesis, and PPy was prepared by chemical polymerization. High-active-mass composite electrodes were fabricated for energy storage in supercapacitors for operation in a sodium sulfate electrolyte. The addition of PPy to CuFe2O4 resulted in a decrease in charge transfer resistance and an increase in capacitance in the range from 1.20 F cm−2 (31 F g−1) to 4.52 F cm−2 (117.4 F g−1) at a 1 mV s−1 sweep rate and from 1.17 F cm−2 (29.9 F g−1) to 4.60 F cm−2 (120.1 F g−1) at a 3 mA cm−2 current density. The composites showed higher capacitance than other magnetic ceramic composites of the same mass containing PPy in the same potential range and exhibited improved cyclic stability. The magnetic behavior of the composites was influenced by the magnetic properties of ferrimagnetic CuFe2O4 and paramagnetic PPy. The composites showed a valuable combination of capacitive and magnetic properties and enriched materials science of magnetic supercapacitors for novel applications based on magnetoelectric and magnetocapacitive properties. [ABSTRACT FROM AUTHOR]

Cubic, perovskite‐structure ABO3‐ and A1−xA'xBO3‐type oxides have been investigated extensively while their hexagonal structure versions have not, even though they are multiferroic and can form heterostructures with hexagonal 2D materials. In particular, multiferroic 2D epilayers may lead to strong magnetoelectric coupling. Hexagonal RFeO3 ferrites, where R is a rare‐earth element (Lu, Yb, etc.), are excellent candidates, but their ferromagnetism is weak. In this work, density‐functional‐theory (DFT) calculations are employed and first show that heavy electron doping of hexagonal LuFeO3 (h‐LFO), namely Lu1−xHfxFeO3 (h‐LHFO), leads to spin‐disproportionation of the Fe sublattices and, especially for x = 1/2 and 2/3, to robust, room‐temperature, out‐of‐plane, collinear ferrimagnetism that is stabilized by a Jahn–Teller metal‐to‐insulator transition. h‐LHFO/h‐2D heterostructures are then shown, where h‐2D is the FE/FM monolayer MnSTe, to stabilize skyrmions without an external magnetic field and their chirality is controlled by an external electric field through the h‐LHFO polarization, opening up a new realm for magnetoelectric applications. [ABSTRACT FROM AUTHOR]

The magnetic properties of van der Waals materials are profoundly influenced by structural defects. The layered antiferromagnet MnPS3 offers a unique opportunity to explore defect‐related magnetism, as Mn2+ vacancies can be generated by the intercalation of specific guest molecules. However, the effectiveness of this process in atomically thin flakes and the extent of the magnetic tunability remain unclear. Here, it is shown that the magnetic properties of MnPS3 can be tailored through the intercalation of different guest molecules. Notably, the insertion of four alkylammonium ions introduces different populations of Mn2+ vacancies, leading to a transition from the pristine antiferromagnetic state to more complex magnetic textures, including a ferrimagnetic state displaying a magnetic saturation of 1 µB per atom. Moreover, it is shown that the intercalation of few‐nm‐thick flakes also leads to the emergence of a ferrimagnetic response. This in‐flake intercalation, which can be monitored in real time using optical microscopy, can be interrupted before completion, generating lateral heterostructures between pristine and intercalated areas. This approach opens the way to the use of partial intercalation to define regions with distinct magnetic properties within a single flake. [ABSTRACT FROM AUTHOR]

We explored the coupling between magnetic and magneto-transport properties in MnBi2Te4 crystals with Fermi energy EF ranging from 10 to 100 meV in the conduction band. Electrical, magnetic, and magneto-transport measurements reveal distinct behaviors depending on EF. At lower EF values (10 meV), MnBi2Te4 exhibits degenerate-semiconductor-like electrical transport and ferrimagnetism, with weak coupling between magneto-resistance and ferrimagnetism. In contrast, MnBi2Te4 displays metallic transport and antiferromagnetism (AFM) at higher Fermi energies, with magneto-resistance strongly coupled to antiferromagnetism and canted antiferromagnetism under a large external magnetic field. Remarkably, Hall measurements demonstrate a pronounced anomalous Hall resistivity (AHR) when the EF of MnBi2Te4 is 10 meV, larger than that reported for other bulk MnBi2Te4 crystals in the literature. Significant AHR is attributed to the Berry-phase effect in electronic-band structure based on first-principles calculation. The evolution of magnetic and magneto-transport properties in EF shifted MnBi2Te4 can be semi-quantitatively explained by the Ruderman–Kittel–Kasuya–Yosida interaction between neighboring MnTe layers. Our work suggests that the strongly Fermi-energy-sensitive magneto-transport properties observed in MnBi2Te4 may be useful in developing magnetic sensors/detectors. [ABSTRACT FROM AUTHOR]

Siderite is a typical iron-bearing carbonate mineral, which is characterized by thermal instability. In this study, the thermal decomposition of natural siderite with magnesium (Mg) isomorphous substitution was performed in a flowing air atmosphere. During the thermal decomposition, X-ray diffraction, Mössbauer spectroscopy, transmission electron microscope, and vibrating sample magnetometer were employed to characterize the samples. Results indicated that siderite primarily transformed into maghemite and Mg–Fe spinel in oxidation decomposition, and no magnetite was detected. The synthetic spinel phases were highly stable and difficult to oxidize even at a roasting temperature of 700 °C because of the magnesium substitution. Owing to the ferrimagnetism of maghemite and Mg–Fe spinel, the magnetism of samples significantly improved during the oxidation decomposition. [ABSTRACT FROM AUTHOR]

Generalized gradient approximation with Hubbard potential (GGA + U) within the framework of density functional theory (DFT), the structural and electronic properties, as well as the magnetic ordering of the quadruple perovskites Y2CuGaTM4O12 (TM = Mn and Fe), are studied. Formation energy indicates that Y2CuGaMn4O12 is more stable than the Y2CuGaFe4O12 and the estimated structural parameters are in good accordance with the experiment. The optimized magnetic energy curves show that these compounds have a type I ferrimagnetic order. According to the Heisenberg model, strong long-range Mn+3–O2−–Cu2+–O2−–Mn+3 interactions are mediated by a super exchange mechanism. The susceptibility data shows that these compounds undergo multiple magnetic transitions due to different magnetic interactions (J1 (Cu+2–Cu+2), J2 (Cu+2–Mn+3), and J3 (Mn+3–Mn+3)). The electronic band profiles and density of states shows the half-metallic character of these compounds and Mn d electrons are responsible for their half-metallic nature. Beside this Mn d state electrons are also responsible for magnetism with addition of Cu atoms instead of Ga. DFT and the Heisenberg model's estimated results are confirmed by magnetic susceptibility. These compounds are anticipated to be appropriate for spintronic applications due to their ferrimagnetic nature and high spin polarization near the Fermi level. [ABSTRACT FROM AUTHOR]

Perpendicularly magnetized Co-based Heusler alloys are promising candidates in high-performance spintronic devices. However, there is a contradiction between thermal stability and damping-like spin–orbit torque (SOT) efficiency in Co-based Heusler alloys with interface-induced perpendicular magnetic anisotropy (PMA). Here, we present epitaxially grown perpendicularly magnetized Mn1+xCo2−xAl (MCA) Heusler alloys through tetragonal distortion. Ferrimagnetism and distortion-induced PMA are obtained in MCA Heusler alloys. A large effective spin Hall angle (θeff) up to 0.33 is experimentally demonstrated in Pt/MCA bilayers, markedly surpassing that in conventional Pt/FM bilayers. Consequently, SOT-induced efficient magnetization switching is realized in Pt/MCA bilayers, with a critical switching current density (Jc) as low as 4 × 107 A/cm2. The large θeff and high SOT efficiency would be attributed to the staggered magnetic exchange torques in the ferrimagnetic MCA Heusler alloys. These findings demonstrate that perpendicularly magnetized ferrimagnetic MCA Heusler alloys are highly promising for high-density SOT-magnetic random-access memory with superior thermal stability and low power consumption. [ABSTRACT FROM AUTHOR]

Present work reports a systematic study on the evaluation of magnetic inhomogeneities in non-stoichiometric Mg 0·5 Ca 0·5 Fe 2 O 4 nanoferrite (MCNF) by conducting exhaustive dc-magnetization, ac-susceptibility and 57Fe Mössbauer spectroscopic measurements and exchange bias investigations using training protocol down to 6 K. Rietveld fitting to PXRD established the formation of anticipated spinel fcc phase of MCNF (non-stoichiometric) along with a minute impurity phase of calcite. Scherrer method and HRTEM micrographs illustrated broad size distribution of MCNF nanoparticles with an average nanocrystallite size of ∼15 nm. Combined 57Fe Mössbauer spectroscopic and dc-magnetization analysis establishes coexistence of ferrimagnetic (67 %) & superparamagnetic (33 %) states at 300 K with notable M s = 22 emu/g, M r = 4 emu/g & H c = 130 Oe and blocking of most of the nanoparticles of MCNF below 300 K. The coercivity followed the size-modified Kneller law for ferrimagnetic nanoparticles and the saturation magnetization abides the Bloch law. Moreover the frequency-dependent ac-susceptibility investigations revealed two magnetic transitions: (i) A transition at ∼ 330 K in the low frequency data attributed to the relaxation of blocked particles of bigger sizes under the superparamagnetic (SPM) regime and (ii) an irregularity at low temperatures is assigned to surface spin glass freezing. Surface spin glass freezing was further affirmed by the ageing experiments and dynamic scaling law. Furthermore, even the best fit to the dynamic scaling couldn't assert the existence of conventional spin glass phase due to slower spin-flip time of surface spins. A soft ferrimagnetic core of MCNF is enveloped with disordered surface spins, which manifest spin glass state. Concurrently, the findings of exchange bias at 30 K and training effect at 6 K affirmed that MCNF nanoparticles are presenting themselves as FM core- SG shell system. Our experimental findings suggested magnetic inhomogeneities comprised of superparamagnetism, ferrimagnetism and disordered surface spin glass state in the non-stoichiometric MCNF. [ABSTRACT FROM AUTHOR]

The preparation of 2D magnetoelectric (ME) nanomaterials with strong ME coupling is crucial for the fast reading and writing processes in the next generation of storage devices. Herein, 2D BaTiO3 (BTO)‐CoFe2O4 (CFO) ME nanocomposites are prepared through a substrate‐free coupling strategy using supercritical CO2. Such 2D BTO‐CFO with strong coupling is built through alternating in‐plane and out‐of‐plane epitaxy stacking, leading to remarkable mutual biaxial strain effects for spin‐lattice coupling. As a results, such strain effect significantly enhances the ferroelectricity of BTO and the ferrimagnetism of CFO, where an unexceptionally high ME coupling coefficient of (325.8 mV cm−1 Oe−1) is obtained for the BTO‐CFO nanocomposites. [ABSTRACT FROM AUTHOR]

We present a study on the structural and magnetic properties of Sr(Fe0.2Mn0.2Co0.2Ti0.2V0.2)O3 (S5BO) high-entropy oxide perovskite thin films. We use synchrotron-based x-ray absorption spectroscopy employing x-ray magnetic circular dichroism (XMCD) and reveal an enhanced presence of high-spin Co2+, which appears to feature a magnetic response opposing that of the two other magnetic transition metal elements, Fe and Mn. This is marked by both opposite XMCD signals and an inverted XMCD hysteresis loop for Co, while Fe and Mn show regularly shaped hysteresis curves, as the picture of a ferrimagnetic ground state emerges for S5BO. [ABSTRACT FROM AUTHOR]

Magnetic nanomaterials showing unique magnetic behaviour have spread their potential applications in various fields. Iron oxide nanomaterials have been developed for their unique properties that they develop at extremely small size. The high surface area to volume ratio, enhanced surface properties, excellent magnetic property with better biocompatibility are the most promising properties of iron oxide nanoparticles (NPs). Hence development of bio-friendly and less toxic iron oxide NPs is the key point of research in recent years. Most importantly, unique physical and chemical properties of magnetite (Fe3O4), maghemite (γ-Fe2O3) and hematite (α-Fe2O3) are significantly important in the field of technological and biological applications. At nanoscale transition metal iron oxide develops superparamagnetism, which is very important and promising for biomedical applications. In the current study Magnetite (Fe3O4) phase of iron oxide has been prepared in the laboratory using the coprecipitation method. In this study less expensive and widely used experimental setup has been designed to observe the size effect in magnetic iron oxide nanoparticles. The structural information was obtained using X-ray diffraction (XRD). XRD result showed the presence of peaks corresponding to magnetite (Fe3O4) phase of iron oxide. The morphology of the particles was studied using Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Magnetic properties were studied using vibrating sample magnetometer (VSM). Theoretical discussion on superparamagnetism has also been done. [ABSTRACT FROM AUTHOR]

To overcome the challenges related to diluted magnetic semiconductors (DMS), significant research efforts are currently underway to develop functional materials to fulfil the requirements of next-generation spintronic devices. This study was planned to investigate a potential DMS material based on Al2CO using first-principles methods. Al2CO is a direct band gap semiconductor with the energy gap of 1.77 eV in such a way that the conduction band minimum is composed of Al 3 s states, whereas the valence band maximum is contributed by p states of carbon and oxygen atoms. The phonon dispersion curves revealed the dynamical stability of Al2CO. The effect of 3d transition metal (TM) dopants doping into the Al2CO on the electronic and magnetic properties was systematically investigated. The cationic site near oxygen is found energetically feasible when compared with the site adjacent to a carbon atom in the host. The dopants produced spin-polarized gap states in an otherwise non-magnetic host. The hybridization of the p states of the host with the d states of dopant pointing to p-d exchange interactions is observed. The doping of Cr in the host exhibited half-metallic nature of the material. To check the magnetic ground state, double doping with the spin-flip configuration of the host was carried out. The results revealed that the entire 3d dopants prefer to adopt antiferromagnetic coupling in Al2CO. The finding demonstrates that Al2CO is a promising host material for creating new DMS to be used in spintronics. [ABSTRACT FROM AUTHOR]

Ce:YIG thin films are taken as an ideal candidate for magneto-optical devices with giant Faraday effect in the near-infrared range, but it is hindered by a limited Ce3+/Ce4+ ratio and a high saturation driving field. To address this issue, Eu doping can increase the Faraday rotation angle by ∼ 40% to 1.315 × 104 deg/cm and decrease the saturation driving field by ∼ 38% to 1.17 kOe in Eu0.75Ce1Y1.25Fe5O12 compared to Ce1Y2Fe5O12 pristine. The mechanism is attributed to the conversion of Ce4+ to Ce3+ and the weakening of ferrimagnetism by Eu doping. This work not only provides strategies for improving Ce3+/Ce4+ ratio in Ce:YIG, but also develops (Eu,Ce):YIG with a promising Faraday rotation angle for magneto-optical devices. [ABSTRACT FROM AUTHOR]

Regulation of electrocatalysis by an external magnetic field has been recently reported, but the physical understanding of what triggers this effect remains elusive. Most cases occur in transition-metal oxychalcogenides with ferromagnetism/ferrimagnetism, but the research on perovskite oxide catalysts is still lacking. In this work, we synthesized a series of Eu element-substituted Ba0.5Sr0.5Co0.8Fe0.2O3 cubic perovskites, and importantly, the regulation of the electrochemical performance by the magnetic field was achieved in Eu0.3(Ba0.5Sr0.5)0.7Co0.8Fe0.2O3 at 273 K, regardless of the direction of the applied magnetic field. Our results promote the use of the magnetic field as an interesting playground to ameliorate electrocatalysis of perovskite oxides close to the paramagnetic state. [ABSTRACT FROM AUTHOR]

Condensed matter physics has often provided a platform for investigating the interplay between particles and fields in cases that have not been observed in high-energy physics. Here, using angle-resolved photoemission spectroscopy, we provide an example of this by visualizing the electronic structure of a noncentrosymmetric magnetic Weyl semimetal candidate NdAlSi in both the paramagnetic and ferrimagnetic states. We observe surface Fermi arcs and bulk Weyl fermion dispersion as well as the emergence of new Weyl fermions in the ferrimagnetic state. Our results establish NdAlSi as a magnetic Weyl semimetal and provide an experimental observation of ferrimagnetic regulation of Weyl fermions in condensed matter. A Weyl semimetal formally requires either broken time reversal symmetry or inversion symmetry. One class of Weyl semimetals-the crystal family of NdAlSi-exhibits both. Here, Li et al perform angle-resolved photoemission spectroscopy measurements on NdAlSi, and observe the formation of an additional Weyl fermion as the material becomes ferrimagnetic. [ABSTRACT FROM AUTHOR]

The structural, magnetic, and dielectric properties of ceramic samples of Yb-doped PbFe2/3W1/3O3 have been investigated by a variety of methods including x-ray powder diffraction, magnetometry, and dielectric spectroscopy. In addition, theoretical investigations were made using first-principles density functional calculations. All the doped samples Pb(Fe1 − xYbx)2/3W1/3O3 (PFYWO) (0.1 ≤ x ≤ 0.5) were found to crystallize in an ordered cubic (F m 3 ¯ m) structure with partial ordering in the B-perovskite sites. Observed changes in the cationic order were accompanied by differences in the dielectric and magnetic responses of the system. While pure PbFe2/3W1/3O3 is antiferromagnetic, the doped Pb(Fe1 − xYbx)2/3W1/3O3 PFYWO samples display excess moments and ferrimagnetic-like behavior, associated with differences in B′ and B″ site occupancies of the magnetic Fe3+ cations. The magnetic transition temperature of the ferrimagnetic phase is found to decrease with increasing Yb content, from TN ∼350 K of the undoped sample down to 137 K for x = 0.5. All PFYWO compounds display a ferroelectric relaxor behavior akin to that of PbFe2/3W1/3O3, albeit our results show significant changes of the frequency and temperature dependence of the dielectric properties. The changes of the properties of PFYWO with increasing Yb substitution can be explained by the changes in the cation size/charge mismatch and the size difference of the two ordered positions. [ABSTRACT FROM AUTHOR]

Using the path probability and lowest approximation of cluster variation method, we study the dynamic and equilibrium properties of a bilayer magnetic system, consisting of two ferromagnetic monolayers antiferromagnetically coupled for different spins (𝜎 = 1/2 and 𝑆 = 1). Firstly, numerical results of the monolayer and total magnetizations are presented under the effect of the diverse physical parameters, and the phase diagrams of bilayer system are discussed. Then, since it is well established that the path probability method is an effective method for the existence of metastable states, the time evolution of monolayer- and total magnetizations is investigated. [ABSTRACT FROM AUTHOR]

Their high tunability of electronic and magnetic properties makes transition‐metal oxides (TMOs) highly intriguing for fundamental studies and promising for a wide range of applications. TMOs with strong ferrimagnetism provide new platforms for tailoring the anomalous Hall effect (AHE) beyond conventional concepts based on ferromagnets, and particularly TMOs with perpendicular magnetic anisotropy (PMA) are of prime importance for today's spintronics. This study reports on transport phenomena and magnetic characteristics of the ferrimagnetic TMO NiCo2O4 (NCO) exhibiting PMA. The entire electrical and magnetic properties of NCO films are strongly correlated with their conductivities governed by the cation valence states. The AHE exhibits an unusual sign reversal resulting from a competition between intrinsic and extrinsic mechanisms depending on the conductivity, which can be tuned by the synthesis conditions independent of the film thickness. Importantly, skew‐scattering is identified as an AHE contribution for the first time in the low‐conductivity regime. Application wise, the robust PMA without thickness limitation constitutes a major advantage compared to conventional PMA materials utilized in today's spintronics. The great potential for applications is exemplified by two proposed novel device designs consisting only of NCO films that open a new route for future spintronics, such as ferrimagnetic high‐density memories. [ABSTRACT FROM AUTHOR]

The magnetic properties of trigonal 3C Fe7S8 nanoparticles, synthesized via the thermal decomposition method, are investigated using temperature-dependent zero-field cooled (ZFC) and field-cooled (FC) magnetization (M–T) curves. The M–T data, recorded at 100 and 1000 Oe, reveal magnetic ordering with high Curie transition temperature (TC > 300 K) in the specimen. The magnetization vs. applied magnetic field (M–H) data measured in the temperature range from 7 to 300 K show that the compound exhibits ferrimagnetic ordering. The values of coercivity (HC), saturation magnetization (M60 kOe) and remanent magnetization (MR) appear to increase at lower measuring temperatures. As the result of increasing M60 kOe at lower measuring temperatures, within the temperature range of 7 to 300 K, the maximum energy product (BHmax) has the highest value of 128 kG Oe at 7 K. [ABSTRACT FROM AUTHOR]

The content of transition‐metal ions and their valence state for three compositions of NixCuyMn3−x−yBO5 are estimated by the methods of X‐ray absorption spectroscopy. In all the three compositions, the copper content does not exceed 0.25. One of the compositions has manganese ions both in the trivalent and bivalent states according to the K‐edge position. The calculations of the total energies of various cation‐ordered structures using the software package Wien2K show that copper ions predominately occupy one site, namely, 2(2d). The measurements of the magnetic properties show two types of magnetic transitions in all the three compositions, with one of them being in the range of 60–75 K and the other one at 10 K. Based on the exchange interactions calculated in the framework of the empirical model, magnetic ordering temperatures are estimated for two‐ and three‐sublattice structures and the magnetic transition in the range of 60–75 K is supposed to be connected with magnetic moment ordering in sites 2 and 3. [ABSTRACT FROM AUTHOR]

The content of transition‐metal ions and their valence state for three compositions of NixCuyMn3−x−yBO5 are estimated by the methods of X‐ray absorption spectroscopy. In all the three compositions, the copper content does not exceed 0.25. One of the compositions has manganese ions both in the trivalent and bivalent states according to the K‐edge position. The calculations of the total energies of various cation‐ordered structures using the software package Wien2K show that copper ions predominately occupy one site, namely, 2(2d). The measurements of the magnetic properties show two types of magnetic transitions in all the three compositions, with one of them being in the range of 60–75 K and the other one at 10 K. Based on the exchange interactions calculated in the framework of the empirical model, magnetic ordering temperatures are estimated for two‐ and three‐sublattice structures and the magnetic transition in the range of 60–75 K is supposed to be connected with magnetic moment ordering in sites 2 and 3. [ABSTRACT FROM AUTHOR]

Ferrimagnets are of interest in spintronics owing to the enhancement of spin transfer and spin–orbit torque in the vicinity of the magnetic compensation point. Here, we study the possibility of achieving compensation at room temperature in Mn4−xNixN films grown on SrTiO3(001) substrates by molecular beam epitaxy. The magnetic and magneto-transport properties of 30-nm-thick epitaxial Mn4−xNixN films (x = 0, 0.1, 0.25, and 0.5) were investigated. Ni introduction in Mn4N causes the spontaneous magnetization (MS) to decrease by 45% at x = 0.1 and by 75% at x = 0.25. All samples exhibited the perpendicular magnetic anisotropy required for spintronic applications as well as displaying a sharp magnetization reversal. Remarkably, the sign of the anomalous Hall resistivity changed in the samples between x = 0.1 and 0.25. Further, the magnetization increased for x = 0 and 0.1 and decreased for x = 0.25 when the temperature was decreased. Based on these results, we propose that there is a magnetic compensation composition between x = 0.1 and 0.25, where the magnetization of Mn4−xNixN becomes zero at room temperature. The small MS and perpendicular magnetic anisotropy of the Mn4−xNixN thin films, thus, make them suitable candidates for use in spin transfer torque-based devices. [ABSTRACT FROM AUTHOR]

We have investigated the structural, magnetic, and thermal transport properties of Co 1 − x Ni x Cr 2 O 4 (0 ≤ x ≤ 1) to check the evolution of structural and magnetic properties upon the introduction of the Jahn–Teller active ion Ni 2 + . The x ≤ 0.95 samples can be indexed with a cubic lattice with the space group Fd3m, whereas the x = 0.98 sample undergoes a cubic-tetragonal structural transition, and the x > 0.98 samples belong to a tetragonal lattice with the space group I41-amd at room temperature. All these samples undergo a paramagnetic–ferrimagnetic transition at T C. A spiral ferrimagnetic ordering at T S is suppressed when the amount of Ni is increased, and the abnormal magnetization at T S for the x = 0.6 and 0.8 samples is not pronounced. The measurements of magnetic hysteresis reveal that the x = 0.4 and 0.6 samples possess a rather large coercivity H C compared with the x = 0 and 1 samples. Specifically, the x = 0.4 and 0.6 samples undergo a short-range antiferromagnetic transition above T C. The magnetic properties of the Ni-doped samples can be understood in terms of the magnetic structure model consisting of longitudinal and transverse magnetic sublattices. [ABSTRACT FROM AUTHOR]

Ferrimagnetic insulator materials are the enabling technology for the development of next‐generation magnetic devices with low power consumption, high operation speed, and high miniaturization capability. To achieve a high‐density memory device, a combined realization of robust saturation magnetization (Ms), controllable magnetic anisotropy, and high resistivity (ρ) are highly demanded. Despite significant efforts that have been made recently, simultaneously achieving significant enhancements in these properties in a soft magnetic insulator material still remains a great challenge, severely limiting their practical application. Herein, a high‐entropy strategy in an ultra‐thin spinel ferrite (CrMnFeCoNi)3O4 film is reported that exhibits concurrently a superior saturation magnetization (MS = 1198 emu cm−3), low coercivity (HC = 90 Oe), and excellent resistivity (ρ = 1233 Ω cm), as well as switchable magnetic anisotropy. The comprehensive lattice probing and microstructure analysis studies reveal that such desirable ferromagnetic properties originate from the high‐quality structurally ordered but compositionally disordered single‐crystal epitaxial structure. The switchable magnetic anisotropy demonstrated in the high‐entropy ferrite film can be attributed to the new antiferromagnetic rock‐salt phase. This work unveils the critical benefits of the high‐entropy strategy for magnetic oxide thin films, which opens up new opportunities for the development of high‐performance magnetic materials. [ABSTRACT FROM AUTHOR]

The influence of the size of dislocation loops on sublattice ferrimagnetism in graphene is studied. It is shown that graphene and the underlying gold layer with Au/Co dislocation loops of various sizes are characterized by ferrimagnetic ordering within atomic layers. Additional gold adatoms under graphene enhance the induced Rashba spin–orbit coupling in graphene but do not destroy the ferrimagnetic order in graphene. Since gold clusters can remain during the intercalation of gold on the surface of graphene and under graphene, the number and size of clusters after intercalation can be controlled to enhance the induced Rashba interaction and to obtain a topological phase in graphene. [ABSTRACT FROM AUTHOR]

The electrical resistivity, magnetic, and galvanomagnetic properties of the cast and rapid melt quenched Mn3Al Heusler alloy have been studied. Rapid melt quenching was found to result in changing the microstructure of the Mn3Al alloy, which leads to substantial changes in its electronic transport and magnetic properties. It was suggested that for the cast and rapid melt quenched Mn3Al alloy frustrated antiferromagnetic and almost compensated ferrimagnetic state could appear, respectively. It is shown that the preparation and treatment of the Mn3Al compound plays a substantial role in the formation of its electronic and magnetic characteristics. [ABSTRACT FROM AUTHOR]

Band structure and topology of magneto-spin–orbit graphene is investigated using the proposed tight-binding model that incorporates both Rashba and sublattice-resolved collinear exchange couplings in a generic ferrimagnetic (FIM) setting for in-plane and out-of-plane magnetization directions. The resulting band structures were analyzed for possibilities to extract the strengths of exchange and Rashba couplings from experimental spin-resolved ARPES measurements of the valley gaps and π -state spin-splittings. It was shown that the topologically trivial in-plane FIM situation admits simple expressions for these quantities, whereas the out-of-plane FIM, which admits a nontrivial band topology, is harder to analyze. The obtained topological phase diagrams for the out-of-plane FIM case show that the anomalous Hall conductance is quite stable with respect to the antiferromagnetic (AFM) interaction, which tends to interfere with the QAHE phase; moreover, the topological phase transition has a rather smooth character with respect to the AFM coupling strength. [ABSTRACT FROM AUTHOR]

Defect-induced magnetic phases of 2D and 3D MnB were discussed. The exciting ferromagnetic behavior of MnB MBene is particularly tracked, including high-rated Mn defects via ab-initio calculations and Monte Carlo simulations. Ground state solution was achieved through GGA in PBESol scheme resulting in magnetic state and moments of Mn ions including the density of states around Fermi level. Magnetic susceptibility and magnetization behavior related to temperature was obtained through Monte Carlo simulations based on the Heisenberg model applying Metropolis criteria. The authors focused on controlling the Curie temperature considering the location of Mn defects. The coexistence of the various defect locations opened a realistic window to estimate Curie temperature consistent with experimental values. Exchange energies of 2D MnB different defect locations quite differ from each other. In addition, magnetic moments of the sheet material were found to be higher than 3D bulk MnB.

We have synthesized a series of vanadium-doped nickel ferrite samples to investigate the impact of this substitution on the material's magnetic properties. The samples' phase purity has been verified by XRD analysis. Micrographs taken with a SEM instrument show the accelerated development of the grains. All of the samples are ferrimagnetic, as shown by Vibrating Sample Magnetometry (VSM), but the saturation magnetization (MS) decreases up to (x = 0.20), after which it increases. The samples are also studied by FMR and using the enhanced simulation conditions, the magnetocrystalline anisotropy constant (K 1) of nickel ferrite is calculated, and it is found to be in excellent agreement with the previous reports. The effect of anisotropy on the strength of the signal is investigated using 57Fe-IFNMR (echo amplitude). Intriguingly, we have found that the magnetocrystalline anisotropy measured by FMR is inversely correlated with the echo amplitude measured by IFNMR. [Display omitted] • Vanadium-doped nickel ferrite samples were synthesized to investigate their magnetic properties. • XRD and Rietveld refinement confirmed phase purity, and SEM showed accelerated grain growth with increased doping. • VSM confirms ferrimagnetism in all samples, with saturation magnetization decreasing until x = 0.20, then increasing. • Magnetocrystalline anisotropy constant (K 1) determined from FMR data shows excellent agreement with earlier theoretical calculations. • Theoretical K 1 shows an inverse correlation with echo amplitude measured by 57Fe-IFNMR. [ABSTRACT FROM AUTHOR]

As an analogue to graphene, germanane/silicane shows a promising prospect in nanoelectronics due to its suitable bandgap, high carrier mobility, low electrical noise, and so on. In this paper, the tunable structural, electronic and magnetic properties of germanane/silicane and its nanoribbons through hydrogen defect clusters are investigated by using first-principles calculations based on density functional theory. The results show that the defect states caused by hydrogen defect clusters can be introduced in the band structure of germanane/silicane, resulting in p-type-liked or n-type-liked doping effect. Moreover, various magnetisms such as ferromagnetism, ferrimagnetism, antiferromagnetism, can be induced and controlled by different types of hydrogen defect clusters. In particular, the corresponding magnetic moments are consistent with the predictions of Lieb theorem. Besides free-standing germanane/silicane, the same results are also shown in the cases of germanane/silicane nanoribbons, whatever it is Armchair or Zigzig and whether the edge is passivated by H or not. Such expedient and flexible way for tuning the structural, electronic and magnetic properties of germanane/silicane and its nanoribbons would be greatly helpful to the germanane/silicane-based nanoelectronics devices in the future. [ABSTRACT FROM AUTHOR]

Inversion symmetry breaking has become a vital research area in modern magnetism with phenomena including the Rashba effect, spin Hall effect, and the Dzyaloshinskii-Moriya interaction (DMI)-a vector spin exchange. The latter one may stabilize chiral spin textures with topologically nontrivial properties, such as Skyrmions. So far, chiral spin textures have mainly been studied in helimagnets and thin ferromagnets with heavy-element capping. Here, the concept of chirality driven by interfacial DMI is generalized to complex multicomponent systems and demonstrated on the example of chiral ferrimagnetism in amorphous GdCo films. Utilizing Lorentz microscopy and X-ray magnetic circular dichroism spectroscopy, and tailoring thickness, capping, and rare-earth composition, reveal that 2 nm thick GdCo films preserve ferrimagnetism and stabilize chiral domain walls. The type of chiral domain walls depends on the rare-earth composition/saturation magnetization, enabling a possible temperature control of the intrinsic properties of ferrimagnetic domain walls.

The appearance of antiferroelectrics (AFE) in the ferrimagnetism (FM) system would give birth to a new type of multiferroic candidate, which is significant to the development of novel devices for energy storage. Here we demonstrate the realization of full antiferroelectrics in a magnetic La0.5Sr0.5Fe12O19 system (AFE+FM), which also presents a strong magnetodielectric response (MD) and magnetoresistance (MR) effect. The antiferroelectric phase was achieved at room temperature by replacing 0.5 Sr2+ ions with 0.5 La2+ ions in the SrFe12O19 compound, whose phase transition temperature of ferroelectrics (FE) to antiferroelectrics was brought down from 174 °C to −141 °C, while the temperature of antiferroelectrics converting to paraelectrics (PE) shifts from 490 °C to 234 °C after the substitution. The fully separated double P-E hysteresis loops reveal the antiferroelectrics in La0.5Sr0.5Fe12O19 ceramics. The magnitude of exerting magnetic field enables us to control the generation of spin current, which induces MD and MR effects. A 1.1T magnetic field induces a large spin current of 15.6 n A in La0.5Sr0.5Fe12O19 ceramics, lifts up dielectric constants by 540%, and lowers the resistance by −89%. The magnetic performance remains as usual. The multiple functions in one single phase allow us to develop novel intelligent devices. [ABSTRACT FROM AUTHOR]

The magnetic superconductors Dy0.8Er0.2Rh3.8Ru0.2B4 (Tc ~ 5.1 K) and Dy0.6Er0.4Rh3.8Ru0.2B4 (Tc ~ 5.8 K) have been prepared by partially substituting Er for Dy in DyRh3.8Ru0.2B4, and their χ(Т), М(B), and (Т) have been studied in detail. The materials have been shown to undergo an antiferromagnetic transition (at ~3 K) similar to that of the magnetic superconductor DyRh3.8Ru0.2B4. Using magnetic moment vs. magnetic field, M(B), measurements for Dy0.8Er0.2Rh3.8Ru0.2B4 and Dy0.6Er0.4Rh3.8Ru0.2B4 samples and the Bean model, we have obtained the critical current density as a function of field, jc(B), and the reduced pinning force as a function of reduced field, Fp(h), for the Er-containing materials. The superconductors with antiferromagnetic order in their magnetic subsystem (Dy0.8Er0.2Rh3.8Ru0.2B4 and Dy0.6Er0.4Rh3.8Ru0.2B4) have been shown to exhibit the largest deviation from the scaling law for h > 0.4. [ABSTRACT FROM AUTHOR]

Structural properties, electronic band profile along with magnetic ordering of the tri-transition quaternary perovskites CaCu3B2Ir2O12 (B = Mn, Fe, Co and Ni) are investigated through generalized gradient approximation plus Hubbard potential (GGA + U) in the framework of density functional theory (DFT). The estimated structural parameters are well consistent with the experiments and it is indicated from formation energy that CaCu3Mn2Ir2O12 is more stable among the series. The optimized magnetic energy curves reveal the spin glass behavior for CaCu3B2Ir2O12 (B = Mn and Fe) and type-I ferrimagnetic order for CaCu3B2Ir2O12 (B = Co and Ni) compounds. The Heisenberg model estimates the J1 (Cu–B), J2 (B–Ir), and J3 (Cu–Ir) interactions that generate the strong long-range interactions through superexchange mechanism. Furthermore, the electronic band profiles reveal that the 3d electrons of Cu and B are localized and responsible for magnetism while the Ir-5d electrons are delocalized and responsible for metallic nature in the compounds. Magnetic susceptibility verifies the estimated results of DFT and Heisenberg model. Due to spin polarization around the Fermi level, low magnetic moments, magnetization, spin glass, and ferrimagnetic nature of these compounds, it is expected that these materials are suitable for spintronic applications. [ABSTRACT FROM AUTHOR]

We studied some magnetic behaviors of the Ising model in a single-wall mixed spin (σ = ½, S = 1) triangular nanotube using the effective field theory with correlations (EFTC), and the differential operator technique (DOT). The effects of exchange interactions as well as the temperature and the applied field on the magnetic properties of the nanotube, such as isotherm and spontaneous magnetizations, were carefully analyzed. We demonstrated that the low-temperature behavior of the magnetization is very sensitive to the exchange interactions involved, especially in the case of competitional couplings. Besides the phase diagram, unusual phenomena have been discovered, especially for opposite exchange interactions where magnetization plateaus and frustration are observed. Several forms of ferrimagnetism have been revealed for judicious choices of exchange and single-ion anisotropy. One of the most notable effects is the occurrence of magnetization jumps and fractional plateaus due to both the geometry and the competition between exchange couplings, on the one hand, and the applied magnetic field, on the other hand. Such plateaus could provide a path toward potential applications of functional ferrimagnets in spintronics and device regulation. [ABSTRACT FROM AUTHOR]

Nanosheets composed of stacked atomic layers exhibit unique magnetic, electrical, and electrochemical properties. Here, we report the effect of iron substitution on the structure and magnetism of nickel hydroxide, Ni(OH)2, nanosheets. Ni(OH)2 and iron-substituted Ni(OH)2 (5, 10, 20, and 50 atomic % Fe substitution) were synthesized using a rapid microwave-assisted hydrothermal process. Scanning and transmission electron microscopy show the materials are polycrystalline nanosheets that aggregate into micron-sized clusters. From X-ray diffraction characterization, iron substitutes into the α-Ni(OH)2 lattice up to 20 at. % substitution. The nanosheets exhibit different in-plane and through-plane domain sizes, and Fe substitution affects the nanocrystallite shape anisotropy. The magnetic response differs with Fe substitution: 0% and 5% Fe are ferromagnetic, while samples with 10% and 20% Fe are ferrimagnetic. The competing interactions between magnetization sublattices and the magnetic anisotropy due to the crystalline and shape anisotropy of the nanosheets lead to magnetization reversal at low temperatures. The correlation between higher coercivity and larger nanocrystalline size anisotropy with higher Fe % supports that magnetic anisotropy contributes to the observed ferrimagnetism. The interplay of morphology and magnetic response with Fe-substituted Ni(OH)2 nanosheets points to new ways to influence electron interactions in layered materials which has implications for batteries, catalysis, sensors, and electronics. [ABSTRACT FROM AUTHOR]