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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]

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]

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]

A theoretical model based on the Landau-Lifshitz-Bloch equation is developed to study the effect of damping-like spin-orbit torque in ferrimagnets, which can capture many experimental findings. For example, the sample changes from Gd to FeCo dominate by increasing temperature, the damping-like spin-orbit torque has a peak at the magnetization compensation temperature, and angular-momentum compensation temperature increases as a function of Gd concentration. In contrast to the ferromagnet system, the switching trajectory in ferrimagnets is found to be precession free. The two sublattices are not always collinear, which produce a large exchange field affecting the magnetization dynamics. The study of material composition shows the existence of an oscillation region at intermediate current density, induced by the nondeterministic switching. Compared to the Landau-Lifshitz-Gilbert model, our developed model based on the Landau-Lifshitz-Bloch equation enables the systematic study of the spin-torque effect and the evaluation of ferrimagnet-based devices. [ABSTRACT FROM AUTHOR]

Samples with inversion parameter values (δ) ranging from 0.27 to 0.14 while maintaining the crystallite size value have been successfully fabricated from commercially available powders by mechanical grinding and thermal annealing treatments at temperatures ranging between 400 and 600 °C. Detailed characterization studies of these samples using X-ray, neutron diffraction and magnetic measurements have confirmed for the first time the simultaneous coexistence at 2 K of short range antiferromagnetic and ferrimagnetic ordering for a wide range of the inversion parameter. The magnetic phase diagram obtained is different from the one previously reported, which shows at 2 K the coexistence of long range antiferromagnetic order and short range order for values of inversion parameters less than 0.1 and the presence of a ferrimagnetic order only for values of δ > 0.2. At room temperature, the Rietveld analysis of NPD patterns and the magnetization curves showed a paramagnetic behavior in the samples with δ ≤ 0.1. For the samples with higher cationic inversion, typical hysteresis curves of ferrimagnetic materials were observed and the saturation magnetization values obtained agree quite well with the net magnetic moment obtained from the Rietveld refinement of the neutron diffraction patterns. [ABSTRACT FROM AUTHOR]

The magnetic properties of the mixed spin − 1/2 and spin − 1 Ising ferrimagnetic nanotube with a hexagonal lattice in the presence of the crystal field are investigated by means of the finite cluster approximation. We examine the effects of the crystal field, the surface shell, and core coupling parameters where the main attention has been paid to study the magnetizations and also the phase diagrams for both transition and compensation temperatures. In the absence of the crystal field, the compensation behavior exists only in a limited range of surface shell and core couplings. By introducing a crystal field, the compensation behavior is maintained and the tricritical behavior occurs depending on the strength of surface shell coupling. [ABSTRACT FROM AUTHOR]

Polycrystalline GdFe1âˆ' x Ni x O3 (x  = 0.00, 0.02, 0.04) samples was synthesised using a glycine assisted solâ€"gel method to investigate the enhanced magnetic and electric properties of Ni substituted GdFeO3 systems. TG-DSC analysis of prepared samples confirms that GdFe1âˆ' x Ni x O3 have good thermal stability in high temperatures. The system has been stabilized in an orthorhombic structure with space group Pbnm. The elemental composition of GdFe1âˆ' x Ni x O3 has been estimated from EDAX spectrum. The results showed oxygen deficiency on increasing the Ni substitution and it has been supported by Rietveld refinement. FE-SEM images and Brunauerâ€"Emmettâ€"Teller analysis reveals that GdFe1âˆ' x Ni x O3 is a highly porous material and its porosity and specific area increases with Ni substitution. Magnetic measurements indicates that the system exhibited ferrimagnetic behaviour at low temperatures and canted antiferromagnetic behaviour at room temperature. For x  = 0.04 Ni content, magnetization reversal for applied field of 25 Oe has been observed. Increased coercivity of GdFeO3 with Ni substitution has been attributed to the grain size effect. From electrical point of view, dielectric permittivity of GdFeO3 has been enhanced with Ni substitution. This enhancement has been attributed to the cumulative effects of hopping of Fe2+â€"Fe3+ ions, grainâ€"grain boundary contribution, and space charge polarization. The role of grainâ€"grain boundary contribution is evident from electric modulus spectrum. The space charge effect has been realized in both impedance spectrum and dielectric loss. Temperature-dependent dielectric studies were conducted to understand the mechanisms and various aspects that contribute to the dielectric enhancement. A highly lossy capacitive nature in the P â€" E loop also suggests space charge effects due to Ni substitution in Fe sites. Availability of free charge carrier concentration is correlated with the optical properties of GdFe1âˆ' x Ni x O3. The decrease of optical band gap (2.5â€"2.21 eV) on increasing Ni content suggests the increasing electronic contribution in the system. [ABSTRACT FROM AUTHOR]

We investigate the switching field distribution and the resulting bit error rate of exchange coupled ferri-/ferromagnetic bilayer island arrays by micromagnetic simulations. Using islands with varying microstructure and anisotropic properties, the intrinsic switching field distribution is computed. The dipolar contribution to the switching field distribution is obtained separately by using a model of a triangular patterned island array resembling 1:4Tb=in² bit patterned media. Both contributions are computed for different thicknesses of the soft exchange coupled ferrimagnet and also for ferromagnetic single phase FePt islands. A bit patterned media with a bilayer structure of FeGd(5 nm)/FePt(5 nm) shows a bit error rate of 10-4 with a write field of 1:16T. [ABSTRACT FROM AUTHOR]

Powders of the system (1-x)Bi0.5Na0.5TiO3-xBiFeO3 (x = 0, 0.02, 0.08, 0.10) are synthesized by the combustion reaction method. The crystal structure and the particle size of Bi0.5Na0.5TiO3 are modified by the incorporation of BiFeO3, as can be seen from the infrared spectroscopy and X-ray diffraction results. The inclusion of iron and the increase in the molar percentage of bismuth in the BNT matrix generate new bonds with a different force constant. The structural analysis showed that the addition of BFO to the BNT does not induce any structural phase transition, preserving the rhombohedral symmetry of the Bi0.5Na0.5TiO3 system. The electrical measurements show that the incorporation of iron increases the conductivity of the system generated by an increase in the concentration of oxygen vacancies; alternatively, the addition of 10% of BiFeO3 generates ferrimagnetic behavior reflected in the magnetic hysteresis curves obtained at room temperature. [ABSTRACT FROM AUTHOR]

Magnetic 2D materials have emerged as a great interest in spintronics due to atomic thickness scaling, low energy switching, and ease in the manipulation of spins. This report demonstrates a facile, bottom‐up, chemical vapor deposition approach for non‐van der Waals (non‐vdWs), 2D chromium (III) sulfide (Cr2S3) with c‐axis orientation, out‐of‐plane magnetic anisotropy (easy axis), and ferrimagnetic ordering. Importantly, the anisotropic magnetic saturation and resistivity of 10.23 mΩ cm reveal a narrow bandgap ferrimagnetism in Cr2S3 (∆EActivation ≈ 22 meV and Eg ≈ 40 meV). The prototype lateral spin‐channel Al/Cr2S3/Al devices exhibit a negative magnetoresistance of ≈25% and ≈15% at 100 K (below Néel temperature) for few‐layer (≈8 nm) and thin‐film (≈50 nm) device structures, respectively, owing to itinerant ferrimagnetism of Cr2S3. The magnetic field‐induced spin polaron formations are quite resilient and enhance the field‐dependent carrier conduction, making it greatly useful for negative magnetoresistance operation. These prototype Al/Cr2S3/Al structures have demonstrated a low power (≈2 µW for 8 µm channel at 10 µA current) operation with a negative field‐dependent resistance coefficient (rM) of ≈−5 × 10−4 Oe−1. The computed rM magnitude is tenfold higher than the bulk Cr2S3. This study identifies the potential of non‐vdW Cr2S3 toward new and robust 2D‐based spintronic applications. [ABSTRACT FROM AUTHOR]

Powders of the system (1-x)Bi0.5Na0.5TiO3-xBiFeO3 (x = 0, 0.02, 0.08, 0.10) are synthesized by the combustion reaction method. The crystal structure and the particle size of Bi0.5Na0.5TiO3 are modified by the incorporation of BiFeO3, as can be seen from the infrared spectroscopy and X-ray diffraction results. The inclusion of iron and the increase in the molar percentage of bismuth in the BNT matrix generate new bonds with a different force constant. The structural analysis showed that the addition of BFO to the BNT does not induce any structural phase transition, preserving the rhombohedral symmetry of the Bi0.5Na0.5TiO3 system. The electrical measurements show that the incorporation of iron increases the conductivity of the system generated by an increase in the concentration of oxygen vacancies; alternatively, the addition of 10% of BiFeO3 generates ferrimagnetic behavior reflected in the magnetic hysteresis curves obtained at room temperature. [ABSTRACT FROM AUTHOR]

The spin-phonon coupling in magnetic materials is due to the modulation of the exchange integral by lattice vibrations. BaFe12O19 M-type hexaferrite, which is the most used magnetic material as permanent magnet, transforms into ferrimagnet at high temperatures, but no spin-phonon coupling was previously observed at this transition. In this letter, we investigated the temperature-dependent Raman spectra of polycrystalline BaFe12O19 M-type hexaferrite from room temperature up to 780K to probe spin-phonon coupling at the ferrimagnetic transition. An anomaly was observed in the position of the phonon attributed to the Fe(4)O6, Fe(5)O6, and Fe(1)O6 octahedra, evidencing the presence of a spin-phonon coupling in BaM in the ferrimagnetic transition at 720 K. The results also confirmed the spin-phonon coupling is different for each phonon even when they couple with the same spin configuration. [ABSTRACT FROM AUTHOR]

Ferrimagnetic insulators promise low-power and high-speed spintronic applications, thanks to their insulating nature and fast dynamics near compensation points. In a ferrimagnetic insulator/heavy metal heterostructure, we investigate field- and current-induced magnetization switching at various temperatures and observe distinct magnetization switching behaviors owing to spin–orbit torque (SOT) and heating effect. We have realized SOT switching across the magnetization compensation temperature and discovered that the SOT switching is strongly heat-assisted: the temperature is always above the compensation temperature while the SOT switching happens in our case. Moreover, we show that the SOT efficiency is strongly magnetization-dependent by characterizing the current dependence of SOT efficiency and explaining the anomalous SOT switching back phenomena in the presence of a titled external field. Our results reveal the critical role of Joule heating on the dynamics of magnetic insulators and pave the way for the application of spintronic devices based on magnetic insulators. [ABSTRACT FROM AUTHOR]

The nature of magnetic ordering in the inverted spinel Co2SnO4 = [Co2+][Co2+Sn4+]O4 is investigated by measuring the temperature dependence of its magnetization (M) and ac-susceptibilities (χ′ and χ″) in different magnetic fields (H) using a superconducting quantum interference device magnetometer. The polycrystalline sample with a grain size of 3-5 μm was prepared by the solid-state route and characterized by x-ray diffraction and scanning electron microscopy. Above the ferrimagnetic Néel temperature TN = 41 K, χdc = M/H fits well with the Néel' expression for the two-sublattice model of ferrimagnetism. The ferrimagnetic ordering is suggested to result from different magnetic moments of Co2+ on the A sites (3.87 μB) and B sites (4.16 μB) and antiferromagnetic molecular field constants with magnitudes NAA = 13.6, NBB = 36.8, and NAB = 33.2. The temperature variations of χ′ and χ″ under various dc-bias fields suggest the existence of a spin-glass (SG) phase for T < TSG = 39.1 K in which only the transverse spin components are frozen below TSG. This co-existence of longitudinal ferrimagnetic order below TN = 41 K and transverse SG state below TSG = 39.1 K is suggested to result from the presence of non-magnetic Sn4+ ions on the B sites. [ABSTRACT FROM AUTHOR]

High field magnetization measurements up to 60 T on free powder samples from GdCo12-xFexB6 (x = 0-3) compounds are reported. The data were used to evaluate the microscopic exchange interaction integral, JGd-3d, between Gd and 3d (Co,Fe) spins. The systems are ferrimagnets; they order magnetically between TC = 95 K for x = 3 and TC = 165 K for x = 0. The low temperature magnetization curves as well as the temperature dependence of intrinsic magnetic parameters are determined by magnetic measurements in pulsed magnetic field. The average magnetic moment <μCo+Fe> per mean transition metal atom (Co + Fe) is small and increases with increasing Fe concentration from 0.44 μΒ for x = 0 to 0.51 μΒ for x = 3 at T = 4 K. From high field magnetization curves, a value of JGd-3d/kB = -4.65 K is derived for x = 0, whereas mean field approximation yields a much larger 3d-3d exchange integral of JCo-Co/kB = 105 K. The obtained results reveal an increase of -JGd-3d/kB with Fe concentration. For x = 0.5, the intersublattice coefficient nGd-3d is found to keep an almost constant value of 5.87 ± 0.13 T*f.u.*μB-1 whatever the temperature in the 2 to 60 K range. [ABSTRACT FROM AUTHOR]

Compensated ferrimagnetic Heusler compounds with high spin polarization and a low net magnetic moment are strategically important materials for spin-logic and further energy-efficient spintronic applications. However, the element-resolved magnetic ordering of these compensated ferrimagnets remains an open issue. Here, we report a direct observation of the spin and orbital moments of the B2 phase Mn2CoAl thin film using the synchrotron-based x-ray magnetic circular dichroism technique. An ferrimagnetic ordering between Mn and Co elements and a compensated-ferrimagnet-like small net magnetic moment of only 0.34 μB/f.u. were observed unambiguously in B2 Mn2CoAl. Antiparallel coupling between Mn and Co is attributed to the mixture of the Mn(B) and Al occupation in the B2 phase Mn2CoAl lattice. This work demonstrates great potential of the compensated ferrimagnetic half-metallic inverse Heusler compounds Mn2CoAl for spintronic applications. [ABSTRACT FROM AUTHOR]

We study the magnetic domain pattern in a ferrimagnetic CoTb thin film using Lorentz transmission electron microscopy. The evolution of domain patterns is captured at different temperatures and external fields. Magnetic dipole skyrmions and bubbles can be created simultaneously by increasing the temperature of the sample and applying appropriate out-of-plane magnetic fields. By tuning the external magnetic fields, it is found that the skyrmions are annihilated at a higher magnetic field compared to bubbles. Moreover, we also find that the in-plane magnetic field influences the formation and the shape of skyrmions and bubbles. Further, micromagnetic simulations are also consistent with the experimental observations. Our findings provide insights into the magnetic field stability of skyrmions. [ABSTRACT FROM AUTHOR]

Magnetic information storage has been achieved by controlling and sensing the magnetic moment orientation of nanoscale ferromagnets. Recently, there has been concentrated effort to utilize materials with antiferromagnetic coupling as a storage medium to realize devices that switch faster, are more secure against external magnetic fields, and have higher storage density. Within this class of materials are ferrimagnets, whose magnetization can be reduced to zero by tuning parameters such as the chemical composition, temperature, and strain. Compared to conventional antiferromagnets, compensated ferrimagnets not only possess the aforementioned speed and density advantages but also allow the use of convenient electrical reading and writing mechanisms due to the existence of inequivalent magnetic sublattices. Recent research has demonstrated fast spin-torque switching, as well as efficient electrical reading with compensated ferrimagnets. Further material and device research using these zero-moment magnets promises a spintronic platform for fast and energy efficient information storage technology. [ABSTRACT FROM AUTHOR]

Magnetism, electronic structure, elastic and thermal properties of Mn2YAl (with Y = Cr, V) have been investigated. The optimized lattice parameters, bulk modulus, and cohesive energy have been obtained. These alloys have the ferrimagnetic state as the most stable magnetic configuration, since the calculations showed a strong Mn-V antiferromagnetic coupling leading to the ferromagnetism of the Mn sublattices. A small and itinerant magnetic moment of Mn at the A site is found, which is antiparallel to the moment of Y at the B position in Mn2YAl (with Y = Cr, V) compounds. The calculated total spin moments are integral values and increase from − 2 μB/f.u. for Mn2VAl to – 1 μB/f.u. for Mn2CrAl with increasing the number of valence electrons. Band structure and total and partial density of states could be calculated via applying the modified Becke Johnson approximation (mBJ). Based on these results, Mn2YAl (with Y = Cr, V) are half-metallic ferrimagnets with the energy gap lies in the majority spin direction and a high-spin polarization (100%). The main difference between these two compounds is that the band gap is increased by 48% (0.210 eV for Mn2CrAl and 0.401 eV Mn2VAl). Elastic anisotropies, brittleness, and thermodynamic properties are determined for the Mn2YAl (with Y = Cr, V). The slight difference in the spatial distributions of Young's moduli of Mn2YAl (with Y = Cr, V) reflects the small differences for the elastic anisotropies of the alloys under consideration. The mechanical stability of Mn2YAl (with Y = Cr, V) alloys are studied based on the elastic constants. The thermal properties are studied and investigated using the quasi-harmonic model, in addition, the temperature effect on heat capacities at constant pressure and volume, entropy, and thermal expansion are analyzed and discussed. [ABSTRACT FROM AUTHOR]

ZrMnSi and HfMnSi half Heusler alloys with magnetic ground state are investigated through density functional theory. The different exchange–correlation functionals (GGA, LDA, PBESol and WC) are used to study these alloys. The equilibrium lattice constants and corresponding ground state energies are calculated using these four approximation methods. From GGA functional, the obtained band gap for ZrMnSi is 1.268 eV and HfMnSi is 1.311 eV. The reported alloys are predicted to be half metals from different potentials, where those alloys show semiconductor character in minority spin channel and also exhibit metallic character in majority spin channel. The studied alloys are mechanically stable and ductile in nature. The total magnetic moment of −3 μ B is obtained in the reported ferrimagnetic alloys. The obtained thermoelectric figure of merit for ZrMnSi and HfMnSi is 0.46 at 1200 K and 0.31 at 1200 K respectively, it shows that these alloys are the potential candidates for waste heat recovery application, and they are also useful for spin flip device application. • We studied the spintronic and thermoelectric properties of the ZrMnSi and HfMnSi. • We predicted the semiconductor character of the Heusler alloys ZrMnSi and HfMnSi. • For both of the Heusler alloys ZrMnSi and HfMnSi the band gap value is 1.29 eV. • The ZT is 0.46 and 0.31 for ZrMnSi and HfMnSi at 1200 K. • ZrMnSi and HfMnSi are best suit for spintronic and thermoelectric applications. [ABSTRACT FROM AUTHOR]

Zero-Field-Cooling/Field-Cooling (ZFC/FC) magnetizations vs. temperature (T) of GDM_Cobalt. [Display omitted] • Structural, magnetic, and magnetocaloric properties of GDM_Nickel,_Iron, and GDM_Cobalt magnetic nanoparticles have been investigated. • The magnetic data show various magnetic behaviors ranging from ferrimagnetic and antiferromagnetic to paramagnetic behaviors. • The Griffiths phase is present in both GDM_Nickel and GDM_Cobalt systems. The GDM_Nickel sample presents RCP = 326 J kg−1. Depending on the type of dopant used, materials can exhibit notably different structural, magnetic, and magnetocaloric properties of Gd 0.5 Dy 0.5 Mn 0.5 Ni 0.5 O 3 (GDM_Nickel), Gd 0.5 Dy 0.5 Mn 0.5 Fe 0.5 O 3 (GDM_Iron), and Gd 0.5 Dy 0.5 Mn 0.5 Co 0.5 O 3 (GDM_Cobalt) magnetic nanoparticles have been examined experimentally. These samples were made using the well-known sol–gel technique. The structure of the systems was ascertained using both X-Ray Diffraction patterns and Scanning Electron Microscopic studies confirming the synthesis of nano-sized perovskites. With the presence of spin-glass and charge-ordering tendencies, magnetic studies revealed that these systems had a variety of magnetic states ranging from ferrimagnetic, antiferromagnetic to paramagnetic behaviors. The presence of Griffiths phase is also detected in both GDM_Nickel and GDM_Cobalt systems. The maximum entropy changes of the GDM_Nickel sample reached the highest value with 14.187 J Kg−1 at 7 T and 326 J kg−1 as a relative cooling power. [ABSTRACT FROM AUTHOR]

• Coexistence of cubic and tetragonal phases in quaternary Heusler alloys, CuCoCrAl and CuFeCrAl, revealed by XRD and neutron diffraction data. • Different magnetic states of the cubic and tetragonal phases, leading to an overall ferrimagnetic behaviour in both the alloys. • Observation of metallic character with weak localization. We have investigated two equiatomic quaternary Heusler alloys CuTCrAl (T = Co and Fe) theoretically and experimentally. Both the alloys have been characterized using X-ray Diffraction (XRD) and neutron powder diffraction (NPD). Refined results of XRD and NPD show the presence of A2/B2 type disorder with the coexistence of mixed-phase of cubic and tetragonal symmetries in CuFeCrAl and CuCoCrAl. NPD magnetic structure refinement indicates the presence of ferrimagnetism with a very low moment at low temperatures. DC magnetization results reveal the presence of weak itinerant ferromagnetic behaviour. Temperature dependence resistivity reflects the metallic character with the presence of weak localization at low temperatures. The coexistence of cubic/tetragonal and ferrimagnetism along with metallic nature in a single system is quite rare, revealing the potential of these alloys for multifarious applications. [ABSTRACT FROM AUTHOR]

Theoretical calculations were performed to investigate the effect of isovalent substitution of Fe with Ga on the magnetic and ferroelectric properties in BiFeO 3 doped with 16.6% and 8.3% Ga. Such substitution will break the G-type anti-ferromagnetic order and enhance the magnetism of BiFeO 3 by forming a stable ferrimagnetic order. The doped system maintains robust spontaneous polarization that is sufficiently large for practical applications at room temperature. The findings explain experimentally observed magnetism. The coexistence of magnetism and ferroelectricity in the doped BiFeO 3 render it a candidate material for application to information storage and spintronics devices. • The coexistence of magnetism and ferroelectricity is observed in Ga-doped BiFeO 3. • The substitutional doping establishes a ferrimagnetism in BiFeO 3 matrix. • The Ga-doped BiFeO 3 material still maintains robust ferroelectricity. [ABSTRACT FROM AUTHOR]

• The C-doped SnO 2 induced a new state resulting the half-metallic characteristic. • The Sn 0.98 Mn 0.02 O 2 shows the antiferromagnetic (AFM) stability belongs to super-exchange coupling type. • For Sn 0.98 Mn 0.02 (O 1-x C x) 2 system, we predicted two statements, the presence of the FM and the ferrimagnetic stabilities. In this paper, the challenge is to investigate the possibility to have the ferromagnetic or/and ferrimagnetic behavior connected to Sn 0.98 Mn 0.02 (O 1-x C x) 2 system at low concentration (x = 0.02, 0.03, 0.04 and 0.05) at room temperature (RT). We utilized the Korringa-Kohn-Rostoker method combined with the Coherent Potential Approximation (KKR-CPA). The C-doped SnO 2 induced the half-metallic characteristic located on the Fermi level and the presence of the double-exchange coupling type belongs to the ferromagnetic (FM). The Sn 0.98 Mn 0.02 O 2 shows the antiferromagnetic (AFM) stability belongs to super-exchange coupling type. For Sn 0.98 Mn 0.02 (O 1-x C x) 2 system, we predicted two statements, the presence of the FM stability where (x = 0.03) and the ferrimagnetic stability where (x = 0.02, 0.04, 0.05). The Curie temperature (T C) can be estimated within the mean field approximation (MFA), our calculations predicted 358.45 K for Sn(O 0.95 C 0.05) 2 and 402.26 K for Sn 0.98 Mn 0.02 (O 0.95 C 0.05) 2. The ferrimagnetic materials are useful for many applications. [ABSTRACT FROM AUTHOR]

In the family of double perovskites, colossal magnetoresistance (CMR) has been so far observed only in half-metallic ferrimagnets such as the known case Sr 2 FeMoO 6 where it has been assigned to the tunneling MR at grain boundaries due to the half-metallic nature. Here we report a new material−Tl 2 NiMnO 6 , a relatively ordered double perovskite stablized by the high pressure and high temperature synthesis−showing CMR in the vicinity of its Curie temperature. We explain the origin of such effect with neutron diffraction experiment and electronic structure calculations that reveal the material is a ferromagnetic insulator. Hence the ordered Tl 2 NiMnO 6 (∼70% of Ni2+/Mn4+ cation ordering) represents the first realization of a ferromagnetic insulating double perovskite, showing CMR. The study of the relationship between structure and magnetic properties allows us to clarify the nature of spin glass behaviour in the disordered Tl 2 NiMnO 6 (∼31% of cation ordering), which is likely related to the clustering of antisite defects and associated with the short-range spin correlations. Our results highlight the key role of the cation ordering in establishing the long range magnetic ground state and lay out new avenues to exploit advanced magnetic materials in double perovskites. Image 1 [ABSTRACT FROM AUTHOR]

The spin Hall magnetoresistance (SMR) effect arises from spin-transfer processes across the interface between a spin Hall active metal and an insulating magnet. While the SMR response of ferrimagnetic and antiferromagnetic insulators has been studied extensively, the SMR of a paramagnetic spin ensemble is not well established. Thus, we investigate herein the magnetoresistive response of the as-deposited yttrium iron garnet/platinum thin film bilayers as a function of the orientation and the amplitude of an externally applied magnetic field. Structural and magnetic characterization shows no evidence for the crystalline order or spontaneous magnetization in the yttrium iron garnet layer. Nevertheless, we observe a clear magnetoresistance response with a dependence on the magnetic field orientation characteristic for the SMR. We propose two models for the origin of the SMR response in paramagnetic insulator/platinum heterostructures. The first model describes the SMR of an ensemble of noninteracting paramagnetic moments, while the second model describes the magnetoresistance arising by considering the total net moment. Interestingly, our experimental data are consistently described by the net moment picture, in contrast to the situation in compensated ferrimagnets or antiferromagnets. [ABSTRACT FROM AUTHOR]

Highlights • Magnetization, Cotton Mouton, and specific heat results obtained on DyIG single crystals are reported. • The first-order nature of the spin reorientation phase transition at T SR = 15 K is confirmed. • This ferrimagnet exhibits low temperature anomaly near the Belov point T B = 42 K. • The data are analyzed taking into consideration previous reports about magnetodielectric effect at T SR and Schottky anomaly around T B. Abstract Measurements of magnetization and Cotton Mouton effect (CM) under external magnetic field (H ex) combined with specific heat experiments at H ex = 0, were performed on dysprosium iron garnet Dy 3 Fe 5 O 12 (or DyIG) single crystals. The low-temperature dependences of some magnetic, magneto-optical and thermodynamic quantities, such as spontaneous magnetization, both magnetic and CM susceptibilities and the excess specific heat due to the contribution of the Dy3+ ions only, give rise to the appearance of two types of anomalies. The first one which is related to the 'low temperature paraprocess' effect, occurs in the region of the 'Belov point' T B predicted at 42 K. Whereas the second one, which is due to the previous first-order spin reorientation phase transition, takes place at T SR = 15 K. The easy axis of magnetization defined by the resultant iron sublattice magnetization vector M Fe , which remains along the 〈1 1 1〉 direction above T SR , changes spontaneously below T SR and becomes aligned along the low symmetry angular 〈u u w〉 phase. The results are analyzed taking into account those reported earlier, such as the negative magnetodielectric property for H ex < 10 kOe and the Schottky effect which are related to the anomalies observed respectively in the temperature dependences of the dielectric constant at T SR and the excess specific heat near T B. [ABSTRACT FROM AUTHOR]

In this paper we propose an extension to the Handrich model considering the fluctuations in exchange energies between ions located in different magnetic sublattices. Thus, each magnetic sublattice has an amorphization parameter that changes with temperature. A systematic study of the magnetization as a function of temperature is performed, which allows to observe significant differences when such fluctuations are not considered. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The electronic and magnetic properties of pure and 50% Ru-doped CrO 2 are studied. • CrO 2 encounters half-metal to metal transition at 50% Ru doping. • The doped compound Cr 0.5 Ru 0.5 O 2 is ferrimagnetic in nature. • Cr 0.5 Ru 0.5 O 2 encounters metal-insulator transition (MIT) at U = 6 eV exhibiting ferromagnetism. • The origin of metallic ferrimagnetic property, MIT and ferromagnetism of Cr 0.5 Ru 0.5 O 2 are investigated sequentially. Abstract The electronic and magnetic properties of Ru-doped tetragonal CrO 2 have been investigated by employing density functional theory (DFT). The host material encounters half-metal to metal transition at 50% Ru substitution for Cr. The Ru addition increases the electrical conductivity by adding free electrons into the minority spin channel near E F. The doped material Cr 0.5 Ru 0.5 O 2 exhibits ferrimagnetic behaviour with a saturation magnetic moment of 0.8 μ B. Eventually, Cr 0.5 Ru 0.5 O 2 encounters metal–insulator transition (MIT) at U = 6 eV showing ferromagnetism. It is revealed for the first time that the segregation of electron from Ru-4dt 2g to Cr-3dt 2g orbital induces Cr3+–Ru5+ charge ordering, which triggers MIT in Cr 0.5 Ru 0.5 O 2 that is accompanied by weak static but strong dynamical electron correlation effect arising from on-site Coulomb interaction U = 6 eV. Additionally, strong Hund's coupling between localized Cr-t 2g and Ru-d xy orbitals is responsible for the ferromagnetic behaviour of Cr 0.5 Ru 0.5 O 2. [ABSTRACT FROM AUTHOR]

Abstract The manganese based heusler compounds are important class of materials having remarkable ferrimagnetic and thermoelectric properties. Among them, Mn 2 RhSi which crystallizes in both Hg 2 CuTi and Cu 2 MnAl type structure have undergone detailed investigation for its electronic, magnetic and mechanical properties in Hg 2 CuTi type structure. However, no studies have been performed on Cu 2 MnAl type structure of Mn 2 RhSi. In this study we have performed a detailed comparative study on electronic, magnetic, mechanical, thermoelectric and lattice dynamical behavior of both types of Mn 2 RhSi structures. The higher value of thermal conductivity reduces the thermo electric figure of merit in the material and has large value of Seebeck coefficient making these alloys as a potential candidate for thermoelectric device application. Our results show high value of spin polarization ratio for Mn 2 RhSi which can increase the efficiency of spintronics devices which further have direct application in magnetic random access memory device. The heusler compound are least studied for their lattice dynamical behavior. In our work, we perform detail investigation on lattice dynamical behavior of both type structures of Mn 2 RhSi. Our calculations revealed the anomalous behavior of optical phonons in Cu 2 MnAl type structure which was attributed to the presence of peak right at the Fermi level in electronic density of states whereas phonon dispersion curves of Hg 2 CuTi type structure confirms its dynamical stability. Highlights • Mn 2 RhSi is half metallic ferrimagnetic material. • Positive values of Cauchy's pressure confirm the metallic & ductile nature of Mn 2 RhSi. • Positive frequencies in the PDC of Hg 2 CuTi type structure confirms the dynamical stability over Cu 2 MnAl type structure. • Large Seebeck coefficient make them suitable thermoelectric material. • Higher value of spin polarization ratio increases the efficiency of spintronics devices. [ABSTRACT FROM AUTHOR]

Understanding spin dynamics in perpendicular exchange coupled ferrimagnetic materials is an issue of crucial importance for progress in information processing and recording technology. In this paper, the Landau-Lifshitz-Gilbert equation at atomistic-level is employed to model the perpendicular interfacial exchange effect in ferrimagnetic FeGd/FeTb soft/hard bilayer structures. Three types of magnetization switching features are identified by tuning the interfacial exchange strength to be weak coupling, partial coupling, and strong coupling. These features have been further verified by the dynamical simulations, showing the switched soft layer could also help the hard layer magnetization switching. Based on the coercivity difference of the soft layer and hard layer, the left- or right-shift perpendicular exchange bias effect has been theoretically modelled. [ABSTRACT FROM AUTHOR]

The spin-1/2 Ising diamond chain in a magnetic field displays a remarkable pseudo-transition whenever it is driven sufficiently close to a ground-state phase boundary between a classical ferrimagnetic phase and a highly degenerate frustrated phase. The pseudo-transition of the spin-1/2 Ising diamond chain relates to intense thermal excitations from a nondegenerate ferrimagnetic ground state to a highly degenerate manifold of excited states with a frustrated character, which are responsible for an anomalous behavior of thermodynamic quantities. Temperature dependences of entropy and specific heat are indeed reminiscent of a temperature-driven phase transition of a discontinuous (entropy) or continuous (specific heat) nature though there are no true singularities of these thermodynamic quantities at a pseudo-critical temperature. [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 Kpwa–Atog Boga (KAB) area lies within the Paleoproterozoic Nyong unit which defines the northwestern edge of the Archean Congo craton in southern Cameroon. Rock types in the area are mainly comprises of garnet gneiss associated with banded iron formations (BIFs). The BIFs and its host rocks were subjected to amphibolite facies metamorphism. The Rare Earth Elements (REE) patterns and the discrimination ratios (e.g., Al 2 O 3 /TiO 2 Cr/Th Th/Sc La/Sc) of the garnet gneiss suggest that they are metasedimentary rocks derived from a felsic parent sources that have undergone intensive weathering. The KAB BIFs exhibit significant concentration of TFe 2 O 3  + SiO 2 (>93 wt%), and lower Al 2 O 3 and TiO 2 contents and high field strength elements (e.g., Hf, Nb, Ta, and Zr). This involves little contamination with continental detritus at their depositional environment. The Post Archean Australian Shale (PAAS)-normalized REE patterns of the KAB BIFs show enrichment in heavy REE and the depletion in light REE with positive La anomalies, which imply that these BIFs precipitated in ambient seawater. Moreover, the contribution of low-temperature hydrothermal fluids during the deposition of the studied BIFs were highlighted through their high superchondritic Y/Ho ratio (mean: 31.48), weak positive Eu/Eu ∗ (SN) ratio (mean: 1.83) and the low contents of transition metals. This suggests that the geochemical characteristics of the KAB BIFs and those of the Paleoproterozoic superior-type BIFs are almost similar. In summary, low-temperature hydrothermal fluids mixed with seawater contributed to the deposition of the KAB BIFs on the continental margin. This depositional setting similar to its host rocks is consistent with the Paleoproterozoic geological history recorded within the Nyong unit. This preliminary study reveals that the KAB BIFs are associated with low grade gold (<5 ppb), which could constitute further prospective mineralization besides the iron ore in the KAB area. [ABSTRACT FROM AUTHOR]

A novel V2O5-ZnO-B2O3 (VZB) glass was introduced into the Li0.42Zn0.27Ti0.11Mn0.1Fe2.1O4 (LiZnTiMn) ferrites for advancing low-temperature cofired ceramics technology and fabricating microwave ferrite devices by the multilayer process. The results reveal that the addition of VZB glass is an effective way to improve the densification, microstructure, and ferrimagnetic properties of the LiZnTiMn ferrites. The relationship among dopant amount, sintering mechanism, and structural distribution characteristic was established, tailoring the foundation of ferrimagnetic performance of low-temperature fired LiZnTiMn composites. The resulting VZB glass as flux promotes the microstructural uniformity and compactness and also provides the optimized physical properties of low-temperature sintered LiZnTiMn composites. An appropriate amount of VZB glass (~0.5 wt%) could enhance the saturation magnetization (from 52.2 to 72.3 emu/g) and remanence ratio of saturation induction (from 0.76 to 0.85) and reduce the coercivity of magnetic induction intensity (from 685 to 199 A/m) of the ferrite composites sintered at ~900 °C. Moreover, the ferromagnetic resonance linewidth of LiZnTiMn composites doped with 0.5 wt% VZB glass decreased from 860 to 195 Oe because of the combined effect of good uniformity and low porosity. Thus, with a low-temperature sintering process, the VZB glass could be a promising additive for achieving low-loss LiZnTiMn ferrite used in microwave devices. [ABSTRACT FROM AUTHOR]

The structural and magnetic properties of doped ferrite Zn 0.3 Cu 0.7 Fe 1.5 Ga 0.5 O 4 have been studied by means of the neutron diffraction method at high pressures up to 4.7 GPa and in temperature range 300–425 K. By increasing the temperature and the pressure, a gradual suppression of the magnetic moments of iron ions in both A and B crystallographic sites was observed. This effect corresponds to a magnetic phase transition from the ferrimagnetic state to paramagnetic one. The lattice parameters, interatomic bond lengths and angles, magnetic moments of iron ions as functions of temperature and pressure were obtained. Upon compression, the magnetic ordering temperature of studied ferrite decreases with a large pressure coefficient dT c / dP  = −19(1) K × GPa −1 . [ABSTRACT FROM AUTHOR]

It is predicted that the ZrCrCoZ(Z=B, Al, Ga, In) compounds with LiMnPbSn-type structure are half-metallic ferrimagnets with a large half-metallic gap by the first-principles calculations. The half-metallicity of the ZrCrCoZ(Z=B, Al, Ga, In) compounds are quite robust to the axial and uniaxial strain. The total magnetic moments in per unit cell are 4 μ B for the ZrCrCoZ(Z=B, Al, Ga, In) compounds and follow the Slater-Pauling rule, which can be attributed to the great spin-splitting. The calculated formation energies are negative for all the ZrCrCoZ(Z=B, Al, Ga, In) compounds, which indicates that those compounds are in the thermodynamic stability and the possibility of synthesis in experiment. [ABSTRACT FROM AUTHOR]

The first-principle calculations of density functional theory have been used to study the structural, elastic, electronic and magnetic properties of Mn 2 RhGe full-Heusler alloy. The present study reveals that the Mn 2 RhGe is stable in X a -type structure and exhibits a half-metallic ferrimagnetic feature at equilibrium lattice constant. In the Mn 2 RhGe, the ferrimagnetic behavior results from antiparallel coupling between Mn (1) and Mn (2) spin moments. The total magnetic moment of Mn 2 RhGe is 3μ B , which obeys to the Slater-Pauling rule. The Mn 2 RhGe keeps the half-metallic character for the lattice parameters ( a ) in the range of 5.73–5.95 Å, but at a = 6.05 Å this behavior destroyed and the compound becomes metallic in nature. Therefore, the Mn 2 RhGe is predicted to be better candidate to explore ferrimagnetic property for possible spintronics applications. [ABSTRACT FROM AUTHOR]

Thermodynamic and magnetic properties of a trilayer nanostructure of hexagonal lattices described by the spin-1/2 Ising model are investigated by the use of the effective-field theory (EFT) with correlations. The results for the magnetization, the free energy, the internal energy, the entropy, the specific heat and the critical frontiers were obtained. The critical temperature and the compensation temperature are investigated with a negative interlayer coupling, in order to clarify the distinction between the ferromagnetic and ferrimagnetic behaviors. From the thermal variations of the total magnetization, the six compensation types can be found, i.e., L-, Q-, R-, S-, P-, and N-types. [ABSTRACT FROM AUTHOR]

Monte Carlo simulation has been carried out to study the magnetization of the mixed spin–5/2 and spin–7/2 Ising ferrimagnetic model on a square lattice with periodic boundary conditions. The total magnetization and the magnetizations of the two sublattices under the effects of exchange interactions and the crystal field anisotropy are studied. The ground–state diagrams are constructed. We obtained different types for the thermal dependence of magnetization. Compensation points where the global magnetization of the system vanishes have been detected for appropriate values of the system parameters. [ABSTRACT FROM AUTHOR]

An isostructural series of transition metal-formate-chloride-hydrate compounds, M3(OOCH)5Cl(OH2) (M = Fe, Co, Ni), have been synthesized using a solvothermal method. These compounds crystallize in the chiral and polar space group P31 and are comprised of three different types of helical chains of edge-sharing M2+-centered octahedra. All three compounds undergo 3D ferrimagnetic ordering at low temperature, and the iron and cobalt analogues exhibit field-induced metamagnetic transitions. The magnetic structure was determined by neutron powder diffraction, revealing ferromagnetic intrachain coupling and antiferromagnetic interchain interactions, with the three chains arranged in a two-up/one-down triangular lattice. As all three chains contain one type of metal in the same spin state, these compounds are rare examples of homospin topological ferrimagnets. [ABSTRACT FROM AUTHOR]

Chiral magnets with topologically nontrivial spin order such as Skyrmions have generated enormous interest in both fundamental and applied sciences. We report broadband microwave spectroscopy performed on the insulating chiral ferrimagnet Cu2OSeO3. For the damping of magnetization dynamics, we find a remarkably small Gilbert damping parameter of about 1 × 10-4 at 5K. This value is only a factor of 4 larger than the one reported for the best insulating ferrimagnet yttrium iron garnet at room temperature. We detect a series of sharp resonances and attribute them to confined spin waves in the mm-sized samples. Considering the small damping, insulating chiral magnets turn out to be promising candidates when exploring non-collinear spin structures for high frequency applications. [ABSTRACT FROM AUTHOR]

Magnetic properties of mixed spin (3/2, 1, 1/2) ferro-ferrimagnetic ternary alloys of the type A y ( B x C 1 − x ) 1 − y are investigated, by means of the Monte Carlo simulation. For this purpose, the influence of concentration, temperature and an external magnetic field on magnetization, magnetic hysteresis loop, magnetic susceptibility and specific heat of ternary alloys with amorphous structures are examined. We found that the compensation temperature exists for some concentrations. Also, it is observed that these ferrimagnetic ternary alloys indicate double hysteresis loop which have been seen theoretically and experimentally in different magnetic alloys. The thermal behavior of magnetization, hysteresis loop and specific heat are also investigated. [ABSTRACT FROM AUTHOR]

Chiral magnets with topologically nontrivial spin order such as Skyrmions have generated enormous interest in both fundamental and applied sciences. We report broadband microwave spectroscopy performed on the insulating chiral ferrimagnet Cu2OSeO3. For the damping of magnetization dynamics, we find a remarkably small Gilbert damping parameter of about 1 × 10-4 at 5K. This value is only a factor of 4 larger than the one reported for the best insulating ferrimagnet yttrium iron garnet at room temperature. We detect a series of sharp resonances and attribute them to confined spin waves in the mm-sized samples. Considering the small damping, insulating chiral magnets turn out to be promising candidates when exploring non-collinear spin structures for high frequency applications. [ABSTRACT FROM AUTHOR]

The hysteresis properties of a kinetic mixed spin (1/2, 1) Ising ferrimagnetic system on a hexagonal lattice are studied by means of the dynamic mean field theory. In the present study, the effects of the nearest-neighbor interaction, temperature, frequency of oscillating magnetic field and the exchange anisotropy on the hysteresis properties of the kinetic system are discussed in detail. A number of interesting phenomena such as the shape of hysteresis loops with one, two, three and inverted-hysteresis/proteresis (butterfly shape hysteresis) have been obtained. Finally, the obtained results are compared with some experimental and theoretical results and a qualitatively good agreement is found. [ABSTRACT FROM AUTHOR]

In the present paper, Ni 2+ doped Mg 0.5 Zn 0.5−x Ni x Fe 2 O 4 ( x = 0, 0.125, 0.250, 0.375, 0.500) ferrite samples prepared by co-precipitation route have been characterized by XRD, FT-IR, FE-SEM, VSM, UV Visible and PL spectroscopy for various physical properties. A transition from superparamagnetic behavior ( x = 0) to soft ferrimagnetic nature ( x > 0) with Ni 2+ addition has been reported. With reduction in crystallite size, ferrite nano-particles have shown an increase in coercivity with lower saturation magnetization. An increase in remanence ratio with Ni 2+ content has been observed. The optical band gap of the prepared samples has been calculated using Tauc plots and have been found to increase with increase in Ni 2+ content from 4.50 eV ( x = 0) to 5.60 eV ( x = 0.500). The PL spectra show band edge emission at lower energy than optical band gap energy for all samples. A cation distribution has been proposed and based on this some theoretical parameters have been calculated which supports our experimental results. Modest values of coercivity and saturation magnetization indicates that these materials may be used in high density information storage devices. [ABSTRACT FROM AUTHOR]