Search

The search for magnetic topological materials has been at the forefront of condensed matter research for their potential to host exotic states such as axion insulators, magnetic Weyl semimetals, Chern insulators, etc. To date, the MnBi2nTe3n+1 family is the only group of materials showcasing van der Waals-layered structures, intrinsic magnetism and non-trivial band topology without trivial bands at the Fermi level. The interplay between magnetism and band topology in this family has led to the proposal of various topological phenomena, including the quantum anomalous Hall effect, quantum spin Hall effect and quantum magnetoelectric effect. Among these, the quantum anomalous Hall effect has been experimentally observed at record-high temperatures, highlighting the unprecedented potential of this family of materials in fundamental science and technological innovation. In this paper, we provide a comprehensive review of the research progress in this intrinsic magnetic topological insulator family, with a focus on single-crystal growth, characterization of chemical disorder, manipulation of magnetism through chemical substitution and external pressure, and important questions that remain to be conclusively answered.

In this paper, the calcium-doped nickel-zinc nano-ferrites [Ni 0.5 Zn 0.5 Ca x Fe 2-x O 4 ; x = 0.00, 0.10, and 0.30] were prepared using the chemical co-precipitation synthesis route and studied for switching field high-frequency device applications. The structural analysis has been completed by analyzing X-ray diffraction (XRD) patterns. The Rietveld refined XRD patterns confirmed the formation of cubic spinel structure of Ca2+ substituted nickel-zinc ferrites. The detection of metal-oxygen bonds present at A and B lattice sites has been unveiled by Fourier transform infrared (FTIR) spectroscopy. The morphological studies obtained through FESEM (Field emission scanning electron microscopy) analysis showed a reduction in the particle size from 70 nm to 53 nm when the concentration of Ca2+ ions in Ni-Zn ferrites was increased. Energy dispersive spectra (EDS) confirmed the presence of elements present in the prepared composition. The structure of a cubic spinel-shaped unit cell has been verified from three active prominent Raman modes (A 1g , A 2g , and T 2g). Diffuse-reflectance spectroscopy (DRS) exhibits the increment in the bandgap values (from 1.55 eV to 1.63 eV) which helps fabricate highly efficient photovoltaic devices. The ferroelectric measurements yielded a rise in polarization values from 1.461 μC/cm2 to 18.228 μC/cm2 for 10 % Ca2+ ion substitution. The tangent loss values declined from 24 to 3 in Ni-Zn ferrites upon substituting Ca2+ ions. The Vibrating sample Magnetometer (VSM) technique found the increment in the saturation magnetization (M s) values from 34.724 emu/g to 54.662 emu/g on substituting up to 30 % Ca2+ ions in Ni-Zn ferrites. These obtained results support the material in switching field distribution for high-frequency applications. The results exhibited that the prepared samples can be applicable for switching devices, filters, and microwave absorption devices. The results revealed the maximum frequency between 12 and 18 GHz which is useful for Ku band absorption. [ABSTRACT FROM AUTHOR]

Augmentation of optical and magnetic properties of ZnO system via mono- and co-doping is an efficient approach to achieve enhanced ferromagnetism and photocatalytic activity. In this scenario, we made an endeavor to prepare the nanocrystalline ZnO, ZnO:Eu, and ZnO:(Eu, Er) samples through a co-precipitation technique. Structural analysis ruled out the effectual substitution of Eu and Er in the ZnO lattice without disturbing the original structure. Both ZnO:Eu and ZnO:(Eu, Er) NPs exhibited lower optical band gap values than pure ZnO. In M − H studies at room temperature, ferromagnetic behavior was observed in ZnO, ZnO:Eu, and ZnO:(Eu, Er) NPs. Expectedly, ZnO:(Eu, Er) NPs showed highest H 2 evolution than both ZnO and ZnO:Eu NPs beneath solar spectrum. The possible roots behind the extended H 2 production are discussed in detail. Hence, ZnO:(Eu, Er) NPs may find in applications is photocatalysis and spintronics. [ABSTRACT FROM AUTHOR]

The reaction of MnCl2·4H2O with HL ((1-methyl-1H-imidazol-2-yl)methanol) and pdH2 (1, 3 propanediol) in a basic MeCN solution results in the formation of a mixed-valence [Mn20] cationic cluster and two [MnIICl4] counter anions. The metallic skeleton of the cluster describes two geometrically equivalent mixed-valent, linked [MnIII6MnII4] supertetrahedra in which nearest-neighbor metal ions have a different oxidation state. Magnetic susceptibility, magnetization data and heat capacity measurements support evidence of predominant ferromagnetic correlations, leading to a s = 22 spin ground state for the [MnIII6MnII4] supertetrahedra, which are pair-linked by a weak antiferromagnetic coupling. The properties are discussed in the context of the magnetocaloric effect and the potential application of this compound in cryogenic refrigeration. [ABSTRACT FROM AUTHOR]

Herein, the influence of Cr3+ dopant on the structural, morphological, optical, photocatalytic, dielectric and magnetic properties of ZnO was investigated for various applications. Pure ZnO and Cr3+ doped ZnO nanoparticles were synthesised by green mediated approach. The synthesised nanoparticles examined by using XRD, SEM, EDX, FTIR, PL, UV–Vis spectroscopy, dielectric and magnetic analysis. XRD confirmed the wurtizte hexagonal structure of synthesised samples and also revealed that the Cr didn't alter the structure of host ZnO. The FTIR analysis revealed the presence of Cr ions in ZnO structures. Doping of Cr ions improved the optical absorbance of ZnO and the optical band gap showed the blue shift with increasing concentration of Cr. The synthesised Cr doped nanoparticles show the outstanding photocatalytic efficiency under solar irradiation against MG pollutant dye. The dielectric constant (ε) improves and dielectric loss (tan (δ)) reduces at lower frequencies with increasing content of Cr. The AC conductivity for doped nanoparticles showed the increasing trend, especially for 4.5 % Cr doped ZnO nanoparticles. The ferromagnetic behavior at room temperature of Cr doped ZnO nanoparticles confirmed by VSM. The obtained results from all investigations make the Cr doped ZnO samples a potential choice for various applications such as, spin based electronic devices and energy storage devices. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials with inherent magnetism have attracted considerable attention in the fields of spintronics and condensed matter physics. The anomalous Hall effect (AHE) offers a theoretical foundation for understanding the origins of 2D ferromagnetism (2D-FM) and offers a valuable opportunity for applications in topological electronics. Here, we present uniform and large-size 2D Cr7Te8 nanosheets with varying thicknesses grown using the chemical vapor deposition (CVD) method. The 2D Cr7Te8 nanosheets with robust perpendicular magnetic anisotropy, even a few layers deep, exhibit a Curie temperature (TC) ranging from 180 to 270 K according to the varying thickness of Cr7Te8. Moreover, we observed a temperature-induced reversal in the sign of the anomalous Hall resistance, correlating with changes in the intrinsic Berry curvature. Additionally, the topological Hall effect (THE) observed at low temperatures suggests the presence of non-trivial spin chirality. Our findings about topologically non-trivial magnetic spin states in 2D ferromagnets provide a promising opportunity for new designs in magnetic memory spintronics. [ABSTRACT FROM AUTHOR]

Bilayer thin films of GdFeO3/Fe97Si3 have been synthesized by RF–magnetron sputtering at different thicknesses of GdFeO3. A pure phase polycrystalline growth of GdFeO3 and Fe97Si3 has been confirmed by XRD measurements. Stress-induced room-temperature magnetocrystalline anisotropy has been confirmed in all the bilayer thin films. A high magnetic moment has been induced in antiferromagnetic GdFeO3 thin films resulting in the ferromagnetic character of all the samples. The ferromagnetic moment was found to be enhanced with increasing thickness of the GdFeO3 layer. The maximum value of the room- temperature magnetic moment has been observed as Ms ~ 9.3 emu/ml in 170-nm-thick GdFeO3 film. Dielectric measurements confirmed the induced magnetocapacitance due to grain boundary accumulation of charge carriers. Magnetic field control of capacitance and current–voltage measurements of these thin films represents a strong potential for the existence of magnetoelectric coupling in GdFeO3/Fe97Si3 films. A maximum 30% rise in magnetocapacitance and a 95.6% increase in tunneling current in an applied 1-kOe magnetic field was obtained for 170-nm-thick GFO thin film. These thin films possess applications in spintronic devices due to the presence of room- temperature magnetocrystalline anisotropy and magnetic control of the electric properties. [ABSTRACT FROM AUTHOR]

We report the influence of oxygen impurities in generating ferromagnetism in GaN doped with Mn, Fe, and Cr through superexchange involving Mn–O–Mn, Fe–O–Fe, and Cr–N–Cr atomic configurations. Density Functional Theory (DFT) calculations demonstrated that these configurations originate within V Ga - O N complex defects by incorporating Mn2+, Fe2+, and Cr3+ ions into gallium vacancies ( V Ga ) sites promoted by the presence of oxygen as a substitutional impurity ( O N ). These co-doped GaN microstructures were synthesized using the thermal evaporation method. Cathodoluminescence (CL) and photoluminescence (PL) measurements confirmed the presence of V Ga - O N complex defects in all GaN-grown samples. X-ray photoelectron spectroscopy (XPS) measurements confirmed the successful incorporation of Mn2+, Fe2+, and Cr3+ ions in GaN samples. SQUID measurements demonstrated room-temperature ferromagnetism with respective saturation magnetization (Ms) and coercive field (Hc) values of ± 1.5 × 10−5 emu and 4 mT for GaN:O,Mn, ± 4.4 × 10−5 emu and 2.6 mT for GaN:O,Fe, and ± 1.7 × 10−5 emu and 2.6 mT for GaN:O,Cr. [ABSTRACT FROM AUTHOR]

We present a systematic investigation of the detailed structural, optical and magnetic properties of ZnO thin films deposited by pulsed laser deposition as a function of varying Al doping from 0% to 5%. The observed features can be associated with strain introduced into the ZnO lattice by the incorporation of Al. Enhanced optical transmittance values close to 95% were achieved in Al-doped ZnO epitaxial films deposited on sapphire substrates. In addition, these films exhibit robust ferromagnetic properties at room temperature with saturation magnetization that varies from 143 to 63 emu/cm3 for Al dopant concentrations from 0% to 5%. It is demonstrated that the saturation magnetization is related to the strain introduced into the lattice with increased Al doping. [ABSTRACT FROM AUTHOR]

Topological semimetals, possessing topologically non-trivial band structures, serve as excellent platforms for realizing topological superconductivity through hard point-contact experiments. In this study, we successfully induce superconductivity in the three-dimensional Dirac semimetal, cubic PtBi2, using ferromagnetic and paramagnetic tips in hard point contact experiments. The induced superconductivity is proven to be insensitive to ferromagnetism and exhibits unconventional features in the point-contact spectra. The highest superconducting transition temperature ( T c ) reaches approximately 5.1 K, and the T c values are proven to have a positive correlation with the coupling between the tip and the sample. Furthermore, we extend our point-contact experiments to trigonal PtBi2, a material possessing a type-I Weyl semimetal band structure and triply degenerate points proximate to the Fermi level. Utilizing both ferromagnetic Ni tips and paramagnetic Ag tips, we successfully enhance superconductivity with a T c of up to 3.0 K in this material. The findings from point-contact measurements reveal that the enhanced superconductivity is compatible with ferromagnetism and the magnetism of the tip can affect the symmetry of the enhanced superconducting state. Given that the lattice structure remains stable under pressure up to 51.2 GPa for cubic PtBi2 and 12.9 GPa for trigonal PtBi2, the emergent superconducting states observed in these two PtBi2 materials could inherit their topological nontrivial nature and be promising candidates for topological superconductor. [ABSTRACT FROM AUTHOR]

We study the effect of hole doping on the Kitaev spin liquid (KSL) and find that for ferromagnetic (FM) Kitaev exchange K the system is very susceptible to the formation of a FM spin polarization. Through density matrix renormalization group simulations on finite systems, we uncover that the introduction of a single hole, corresponding to ≈1% hole doping for the system size we consider, with a hopping strength of just t ~ 0.28K is enough to disrupt fractionalization and polarize the spins in the [001] direction due to an order-by-disorder mechanism. Taking into account a material relevant FM anisotropic exchange Γ drives the polarization towards the [111] direction via a transition into a topological FM state with chiral magnon excitations. We develop a parton mean-field theory incorporating fermionic holons and bosonic magnons, which accounts for the doping induced FM phases and topological magnon excitations. We discuss experimental implications for Kitaev candidate materials. [ABSTRACT FROM AUTHOR]

A facile method has been employed to synthesize pristine and Cr-doped SnS2 (Cr: SnS2) nanoplates (Sn1-xCrxS2, here x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) and Cr: SnS2 nanoplates (NPs) were successfully synthesized via hydrothermal method. The nanoplates' structure was hexagonal, with a preference for orientation along the (001) plane; there was no evidence of additional undesirable phases. FTIR and EDX were used to observe the existence of functional groups in the samples where Sn-S bonds were present in each of the produced pristine and Cr: SnS2 nanoplates. XPS measurements demonstrated the existence of Sn, S, and Cr. FESEM revealed that the morphological properties of the nanoplates included several hexagonal grains. Magnetic characterizations showed that with increasing doping concentration of Cr, SnS2 nanoplates become superparamagnetic from ferromagnetic. The band gap values for the pristine and Cr: SnS2 nanoplates calculated from the absorbance spectra decreased from 2.53 to 2.08 eV with an increase in doping concentration. The photoluminescence spectra of the pristine SnS2 and Cr: SnS2 nanoplates exhibit two strong emission peaks at around 562 and 666 nm for an excitation wavelength of 420 nm. The Cr: SnS2 nanoplates have demonstrated the resistive behavior of the sample. The Cr: SnS2 nanoplates have shown good photocatalytic activity towards the decolorization of rhodamine B under visible irradiation.Article highlights: Hydrothermally synthesized pristine SnS2 and Cr: SnS2 nanoplates exhibit hexagonal crystal structures and the hexagonal shape of layered nanoplates is apparent in both cases. The ferromagnetic order is introduced by Cr doping in SnS2 which increases the formation of dilute magnetic semiconductors that can therefore be used in spintronic devices. The Sn0.6Cr0.4S2 photocatalyst shows the highest photocatalytic activity and a degradation efficiency of 71%, which is 3.4 times higher than the pure SnS2 catalyst. [ABSTRACT FROM AUTHOR]

Using state-of-the-art first-principles electronic-band-structure calculations alongside density functional theory, we investigated the structural, elastic, electronic, and magnetic properties of LiMnZ2 (Z = Se, Te) compounds with a trigonal structure. Initially, we determined the equilibrium lattice structure and atomic positions, which aligned well with experimental values. Ferromagnetism was shown to be more favorable than the non-magnetic state. The elastic constants, cohesive energies, and formation energies indicated that the studied compounds were mechanically stable in the experimentally determined trigonal lattice. The analysis of spin-polarized band structures and density of states revealed that both LiMnZ2 compounds exhibited perfect half-metallic characters. The total spin magnetic moment per formula unit adhered to the Slater–Pauling rule, being exactly 4 μΒ, mainly concentrated at the Mn atoms due to the strong spin polarization of the Mn d orbitals. We anticipate that our results will prompt further experimental and computational studies for the application of these layered materials in practical devices. [ABSTRACT FROM AUTHOR]

Here, by using angle-resolved photoemission spectroscopy, we showed that Bi2−xCrxSe3 single crystals have a distinctly well-defined band structure with a large bulk band gap and undistorted topological surface states. These spectral features are unlike their thin film forms in which a large nonmagnetic gap with a distorted band structure was reported. We further provide laser-based high resolution photoemission data which reveal a Dirac point gap even in the pristine sample. The gap becomes more pronounced with Cr doping into the bulk of Bi2Se3. These observations show that the Dirac point can be modified by the magnetic impurities as well as the light source. [ABSTRACT FROM AUTHOR]

We synthesized La2NiO4 nanostructures using the cationic surfactant-based reverse micellar route and reported on the effect of the size and shape of the La2NiO4 nanostructures on their magnetic and photoelectrochemical properties. We satisfactorily refined the powder X-ray diffraction data in the tetragonal space group, I4/mmm. Magnetic susceptibility measurements were performed on all samples within the range of 5–300 K. The Curie–Weiss law determines the magnetic susceptibility of bulk La2NiO4, and a negative value for the Weiss temperature indicates antiferromagnetic exchange. The field-dependent magnetization curves of bulk La2NiO4 suggest a canted antiferromagnetic behaviour. The Mott–Schottky plot demonstrates that La2NiO4 is a p-type semiconducting material with holes as the primary charge carriers. Chronoamperometric measurements for these nanomaterials demonstrate excellent photostability of photocurrent. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) layered materials have been studied in depth during the past two decades due to their unique structure and properties. Transition metal (TM) intercalation of layered materials have been proven as an effective way to introduce new physical properties, such as tunable 2D magnetism, but the direct growth of atomically thin heteroatoms-intercalated layered materials remains untapped. Herein, we directly synthesize various ultrathin heteroatoms-intercalated 2D layered materials (UHI-2DMs) through flux-assisted growth (FAG) approach. Eight UHI-2DMs (V1/3NbS2, Cr1/3NbS2, Mn1/3NbS2, Fe1/3NbS2, Co1/3NbS2, Co1/3NbSe2, Fe1/3TaS2, Fe1/4TaS2) were successfully synthesized. Their thickness can be reduced to the thinnest limit (bilayer 2D material with monolayer intercalated TM), and magnetic ordering can be induced in the synthesized structures. Interestingly, due to the possible anisotropy-stabilized long-range ferromagnetism in Fe1/3TaS2 with weak interlayer coupling, the layer-independent magnetic ordering temperature of Fe1/3TaS2 was revealed by magneto-transport properties. This work establishes a general method for direct synthesis of heteroatom-intercalated ultrathin 2D materials with tunable chemical and physical properties. The intercalation of heteroatoms has been demonstrated to be an effective approach to introduce new physical properties in 2D layered materials (2DMs). Here, the authors report a flux-assisted growth method to synthesize various ultrathin heteroatoms-intercalated 2DMs, showing evidence of anisotropy-stabilized long-range ferromagnetism in Fe1/3TaS2. [ABSTRACT FROM AUTHOR]

Transition-metal doped topological insulators have been widely explored since the observation of quantum anomalous Hall effect (QAHE). Subsequently, the magnetic (Pb,Sn)(Te,Se) was predicted to possibly possess a high-temperature QAHE state. However, the fundamental understanding of Cr-doping-induced ferromagnetism in this system remains unclear. Here, we report the stable ferromagnetism in the high-crystalline Cr-doped SnTe films. Upon Cr doping, the magnetoconductance unveils a crossover from weak antilocalization to weak localization. Further increasing the Cr concentration to Cr0.17Sn0.83Te introduces a strong ferromagnetism with a Curie temperature of ~140 K. We detected a sizable spin moment ms = 2.28 ± 0.23 μB/Cr and a suppressed orbital moment ml = 0.02 μB/Cr. Cr dopants prefer to substitute the Sn sites and behave as divalent cations, as indicated by the experimental results and density function theory calculations. The controllable growth of magnetic SnTe thin films provides enlightenment towards the high-temperature QAHE in magnetic TCIs for the desired dissipationless transport in electronics. [ABSTRACT FROM AUTHOR]

Doped semiconductors are more advantageous than pure semiconductors, because doping of a semiconductor can tune electrical conductivity and optical bandgap engineering that allows flexible designs of microelectronic and optoelectronic devices, respectively. In the present work, pure and Mn-doped SnO2 nanocrystallites have been prepared using single-step wet chemical method calcined at 500 °C and 650 °C to investigate structural, optical, impedance, and ferromagnetic properties. X-ray diffraction confirmed single-phase Mn-doped SnO2, and NEXAFS spectra further revealed + 2 oxidation state of Mn ions in SnO2. The surface morphology depicted densely packed grains and optical spectra showed Mn and temperature-dependent variation of bandgaps. While dielectric and impedance study disclosed frequency response and dominance of grains resistance. Further, conduction mechanism and room temperature ferromagnetism were improved with doping and sintering temperature. Hence, prepared compounds are attractive for frequency-related devices and data storage applications. [ABSTRACT FROM AUTHOR]

The effect of Ru-substitution (5–15 %) on the charge ordering of Y 0.5 Ca 0.5 MnO 3 has been investigated in this paper. Ru, existing in different oxidation states such as Ru4+ and Ru5+, plays an immense role in causing ferromagnetic (FM) superexchange interactions with Mn3+ ions. This, combined with the FM double-exchange interactions between Mn3+ and Mn4+ ions, destroys charge ordering. The development of ferromagnetism in Ru-substituted compounds is understood experimentally through the remarkable enhancement of dc magnetization with a simultaneous shift of T C from 57 K to 95 K with increasing Ru content from x = 0.05 to x = 0.15. The appearance of hysteresis for higher doping concentrations further confirms the FM nature. Concomitant with the favorable impact on the magnetic nature, there is also a development of magnetocaloric properties upon Ru-substitution. The maximum magnetic entropy change for x = 0.05 to 0.15 that was found to peak at T C ranges from 1.08 J/kg/K to 2.8 J/kg/K respectively for a field change of 9 T. The corresponding relative cooling power (RCP) increases from 76 J/kg to 324 J/kg indicating a significant growth of RCP with Ru substitution. These salient features of Ru-doped Y 0.5 Ca 0.5 MnO 3 would make it a suitable candidate for magnetic refrigeration. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales is the property of Academia Colombiana de Ciencias Exactas, Fisicas y Naturales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, we have studied the microstructure and unusual ferromagnetic behavior in epitaxial tin dioxide (SnO2) films implanted with 40 keV Co+ ions to a high fluence of 1.0 × 1017 ions/cm2 at room or elevated substrate temperatures. The aim was to comprehensively understand the interplay between cobalt implant distribution, crystal defects (such as oxygen vacancies), and magnetic properties of Co-implanted SnO2 films, which have potential applications in spintronics. We have utilized scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM), differential thermomagnetic analysis (DTMA), and ferromagnetic resonance (FMR) to investigate Co-implanted epitaxial SnO2 films. The comprehensive experimental investigation shows that the Co ion implantation with high cobalt concentration induces significant changes in the microstructure of SnO2 films, leading to the appearance of ferromagnetism with the Curie temperature significantly above the room temperature. We also established a strong influence of implantation temperature and subsequent high-temperature annealing in air or under vacuum on the magnetic properties of Co-implanted SnO2 films. In addition, we report a strong chemical effect of ethanol on the FMR spectra. The obtained results are discussed within the model of two magnetic layers, with different concentrations and valence states of the implanted cobalt, and with a high content of oxygen vacancies. [ABSTRACT FROM AUTHOR]

The reaction of MnCl2·4H2O with HL ((1-methyl-1H-imidazol-2-yl)methanol) and pdH2 (1, 3 propanediol) in a basic MeCN solution results in the formation of a mixed-valence [Mn20] cationic cluster and two [MnIICl4] counter anions. The metallic skeleton of the cluster describes two geometrically equivalent mixed-valent, linked [MnIII6MnII4] supertetrahedra in which nearest-neighbor metal ions have a different oxidation state. Magnetic susceptibility, magnetization data and heat capacity measurements support evidence of predominant ferromagnetic correlations, leading to a s = 22 spin ground state for the [MnIII6MnII4] supertetrahedra, which are pair-linked by a weak antiferromagnetic coupling. The properties are discussed in the context of the magnetocaloric effect and the potential application of this compound in cryogenic refrigeration.

Spin-state transitions are an important research topic in complex oxides with the diverse magnetic states involved. In particular, the low-spin to high-spin transition in LaCoO3 thin films has drawn a wide range of attention due to the emergent ferromagnetic state. Although various mechanisms (e.g., structural distortion, oxygen-vacancy formation, spin-state ordering) have been proposed, an understanding of what really underlies the emergent ferromagnetism remains elusive. Here, the ferromagnetism in LaCoO3 thin films is systematically modulated by varying the oxygen pressure during thin-film growth. Although the samples show dramatic different magnetization, their cobalt valence state and perovskite crystalline structure remain almost unchanged, ruling out the scenarios of both oxygen-vacancy and spin-ordering. This work provides compelling evidence that the tetragonal distortion due to the tensile strain significantly modifies the orbital occupancy, leading to a low-spin to high-spin transition with emergent ferromagnetism, while samples grown at reduced pressure demonstrate a pronounced lattice expansion due to cation-off-stoichiometry, which suppresses the tetragonal distortion and the consequent magnetization. This result not only provides important insight for the understanding of exotic ferromagnetism in LaCoO3 thin films, but also identifies a promising strategy to design electronic states in complex oxides through cation-stoichiometry engineering.

In the present work, we investigate the influence of cobalt (Co) doping on the structural and magnetic properties of cobalt-doped silicon carbide (Co-SiC) thin films. The films were fabricated using DC/RF magnetron sputtering technique on Si (100) substrates at a temperature of 1200°C, with varying Co concentrations ranging from 5 to 16 at. (at%. X-ray diffraction (XRD) analysis unveiled the co-existence of CoSi2 and SiC phases in all the thin films. Surface morphological study through atomic force microscopy (AFM) revealed the densely packed nature of the films. Field emission scanning electron microscopy (FE-SEM) study showed that particles are uniformly distributed at the surface of the substrate. According to UV measurements, the films have high transmittance in the visible range, and as Co concentration rises, transmittance decreases. A magnetic phase transition from superparamagnetic to ferromagnetic behavior occurred with Co content surpassing 8 at% in the SiC thin films. Moreover, an increase in coercivity was observed from 38 Oe to 316 Oe as the doping concentration increased from 10 to 16 at%. This study represents an exploration into the induction of ferromagnetism through moderate Co doping in SiC thin films.

Two-dimensional intrinsic magnetic materials with high Curie temperature are promising candidates for next-generation spintronic devices. In this work, we design two kinds of two-dimensional transition metal nitrides, VN2 and FeN2, both with a hexagonal honeycomb lattice. Based on the formation energy, and phonon spectra calculations as well as the molecular dynamics simulations, their structural stability is demonstrated. Then, we determine the ferromagnetic ground states of VN2 and FeN2 monolayers through the energy calculations, and the Curie temperatures of 222 K and 238 K are estimated by solving the Heisenberg model using the Monte Carlo simulation method. Hence, the VN2 and FeN2 monolayers are demonstrated to be new two-dimensional ferromagnetic materials with high temperature ferromagnetism or large-gap half-metallicity. [ABSTRACT FROM AUTHOR]

In this current investigation, a straightforward method is presented for synthesis of Yb-doped SnO 2 (Yb = 0%, 0.5%, 1.5%, 3% and 5%) NPs using a sol-gel approach. Various techniques were used to analyze the surface morphology, crystalline structure, chemical composition, and optical properties of the prepared samples. XRD, FTIR, and HRTEM confirmed nanoparticle formation. Raman, XPS, and PL spectroscopy were employed to examine electronic, optical properties, and lattice defects. Introducing Yb dopant into Yb-SnO 2 NPs enhanced their optical features, as indicated by a significant red shift. These particles exhibited impressive catalytic efficiency, degrading 98% of a 10 ppm RB dye solution within a 60-min period under UV light irradiation. Furthermore, the recyclability analysis demonstrated that the 5% Yb catalyst can be recycled multiple times. Scavenger tests were performed for the 5% Yb sample to explore primary active species involved in the degradation process. The magnetic features of the synthesized samples were investigated using VSM analysis, revealing an increase in M max from 3.98 × 10−3 to 10.40 × 10−3 emu/g. This enhancement was associated with the activation of the FCE, induced by the presence of oxygen vacancies. These findings are instrumental in propelling the advancement of sophisticated materials for both sustainable wastewater treatment and applications in spintronics. [ABSTRACT FROM AUTHOR]

The magnetic shielding device, made of high-permeability soft magnetic material, is sensitive to external influences and requires a protective steel enclosure. A steel enclosure, being strongly ferrimagnetic, can alter the surrounding magnetic field distribution, thus impacting the shielding effectiveness. This study proposes a novel analytical approach to quantify this effect, which has not been previously researched. The method develops a simplified finite element simulation model based on the structural symmetry of the steel enclosure. By using this model, this study analyzes the impact of steel structures with varying heights, widths, and remanent magnetization values. The validity of the method is confirmed through experimental tests on steel buildings. The findings offer insights into the optimal placement of magnetic shielding systems and provide theoretical guidance for designing large-scale magnetic shielding devices. [ABSTRACT FROM AUTHOR]

This study introduces a novel magnetic nanohybrid material consisting of ferromagnetic (FM) bcc Fe–Co nanoparticles (NPs) grown on nanodiamond (ND) nanotemplates. A combination of wet chemistry, which produces chemical precursors and their subsequent thermal treatment under vacuum, was utilized for its development. The characterization and study of the prepared samples performed with a range of specialized experimental techniques reveal that thermal treatment of the as-prepared hybrid precursors under a range of annealing conditions leads to the development of Co-rich Fe–Co alloy NPs, with average sizes in the range of 6–10 nm, that exhibit uniform distribution on the surfaces of the ND nanotemplates and demonstrate FM behavior throughout a temperature range from 2 K to 400 K, with maximum magnetization values ranging between 18.9 and 21.1 emu/g and coercivities ranging between 112 and 881 Oe. Moreover, 57Fe Mössbauer spectroscopy reveals that apart from the predominant bcc FM Fe–Co phase, iron atoms also participate in the formation of a secondary martensitic-type Fe–Co phase. The emergence of this distinctive phase is attributed to the diffusion of carbon atoms within the Fe–Co lattices during their formation at elevated temperatures. The source of these carbon atoms is related to the unique morphological properties of the ND growth matrices, which facilitate surface sp2 formations. Apart from their diffusion within the Fe–Co NP lattice, the carbon atoms also reconstruct layered graphitic-type nanostructures enveloping the metallic alloy NPs. These non-typical nanohybrid materials, reported here for the first time in the literature, hold significant potential for use in applications related, but not limited to, biomedicine, biopharmaceutics, catalysis, and other various contemporary technological fields. [ABSTRACT FROM AUTHOR]

Searching for multiferroic materials with ferromagnetic (FM) and ferroelectric (FE) properties holds promise for ultra‐high‐density and low‐energy‐consumption memory device applications, but 2D materials with both properties are rare. Herein, a general strategy to achieve nonvolatile electric field control of magnetism in the bilayer (BL) α‐In2Se3 by hole doping is proposed. By first‐principles calculations, it is demonstrated that hole doping can induce robust ferromagnetism in the bilayer α‐In2Se3 due to its unique flat Mexican‐hat‐shape valence band structure. Such band edges cause van Hove singularities (VHS), and proper hole doping can lead to time‐reversal symmetry breaking. The bilayer α‐In2Se3 exhibits ferromagnetism and ferroelectricity within a wide range of doping concentrations, resulting in an unexpected multiferroic phase. Furthermore, when the electrical polarization of α‐In2Se3 flips from downward to upward, it becomes non‐magnetic (NM) from ferromagnetic states in the As‐substituted bilayer α‐In2Se3, which can work as a nonvolatile magnetic storage unit. Remarkably, the As‐substituted bilayer α‐In2Se3 exhibits an enhanced magnetic moment of 1.2 μB per AsSe due to substantial charge transfer across the interface. Notably, the mechanism of electrically controlled magnetism is elucidated as the coupling among the Mexican‐hat‐like dispersion, ferromagnetism, and ferroelectricity. The findings offer a promising strategy for electrical writing and the magnetic reading memory device. [ABSTRACT FROM AUTHOR]

The induced ferromagnetic behaviour and defect analysis of the undoped, Ni doped SrSnO 3 nanostructures are examined. The undoped and Ni doped SrSnO 3 (SSO) nanostructures crystallized in the orthorhombic perovskite structure, and show local structural disorders on vibrational spectroscopic analysis. The electron micrographs are witnessed rod type morphology for pure SrSnO 3 and corals for Ni doped compounds. The oxidation states of elements and presence of oxygen vacancies are identified. The sharp optical absorption behaviour resulted in reduction of optical band gap. Positron annihilation spectroscopy (PAS) studies reveal the presence of site-specific intrinsic defects of considerable concentration and their consequential effect on doping. PAS significantly showed that Schottky-type V Sn and V Sr-XO complexes in undoped SSO. The addition of Ni2+ results in the reduction of V Sr – O and the formation of Ni2+-V O -Ni2+ defect complexes. The EPR spectra show the signal with g value of 2.2432. The appearance of RT ferromagnetism could be attributed to the defects, F -center exchange (FCE) interactions in Ni-doped SSO nanostructures. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) ferromagnets have attracted significant interest for their potential in spintronic device miniaturization, especially since the discovery of ferromagnetic ordering in monolayer materials such as CrI3 and Fe3GeTe2 in 2017. This study presents a detailed investigation into the effects of the Hubbard U parameter, biaxial strain, and structural distortions on the magnetic characteristics of T″-phase VTe2. We demonstrate that setting the Hubbard U to 0 eV provides an accurate representation of the observed structural, magnetic, and electronic features for both bulk and monolayer T″-phase VTe2. The application of strain reveals two distinct ferromagnetic states in the monolayer T″-phase VTe2, each characterized by minor structural differences, but notably different magnetic moments. The T″-1 state, with reduced magnetic moments, emerges under compressive strain, while the T″-2 state, featuring increased magnetic moments, develops under tensile strain. Our analysis also compares the magnetic anisotropy between the T and T″ phases of VTe2, highlighting that the periodic lattice distortion in the T″-phase induces an in-plane anisotropy, which makes it a material with an easy-axis of magnetization. Monte Carlo simulations corroborate our findings, indicating a high Curie temperature of approximately 191 K for the T″-phase VTe2. Our research not only sheds light on the critical aspects of the VTe2 system but also suggests new pathways for enhancing low-dimensional magnetism, contributing to the advancement of spintronics and straintronics. [ABSTRACT FROM AUTHOR]

An excellent fit between the theoretical and experimental studies of the related to structure, optics, and magnetism features of pristine and cerium-modified Zn-O NPs prepared through the wet chemical technique. Refining the XR-D pattern using the Rietveld-method reveals that the samples have a hexagonal Wurtzite structure. Absorption spectra reveal a shrinking bandwidth gap as cerium doping increases, substantiating ce2+ ion's essential function in ZnO's spectral qualities. The narrowing of the bandwidth gap due to the presence of impurity states was also verified by first-principles calculations. The residual magnetization increases with Cerium doping, and magnetic tests show roomtemperature weak-ferromagnetism (RTFM). In addition, ferromagnetism for cerium doping is confirmed by both first-principles calculations and experiments. Theoretical calculations imply that the cerium atoms may agglomerate to generate metallicantiferromagnetic chromium oxide when cerium doping reaches 8%. At ambient temperature, however, ferromagnetic behaviour is feasible since both ferromagnetic and antiferromagnetic behaviour are degraded when cerium is widely disseminated throughout the lattice as revealed by XRD studies. [ABSTRACT FROM AUTHOR]

With the aim of improving and investigating magnetocaloric insights for spintronic applications, we investigated the electronic structure of Cr-doped AlSb compounds via first-principles calculations using the KKRCPA-DFT method. Here, we investigated the stability of alloy materials as a function of magnetic contamination. A stable semimetallic ferromagnetic phase can be obtained by introducing the Cr element into AlSb, which is inherent in nonmagnetic semiconductors. The total magnetic moment of the doped material changes from 0.1167 µB to 0.716 µB for 4% and 25% Cr, respectively. Curie temperature changed to 740 K at 25% Cr concentration. [ABSTRACT FROM AUTHOR]

In recent times, there has been a significant focus on semiconductive magnetic nanomaterials due to their potential in photocatalytic applications, primarily because of their easy recoverability. In this work, CoY x Fe 2- x O 4 nanoparticles (with varying x values: 0, 0.05, 0.10, 0.15, and 0.20) were successfully synthesized. The incorporation of Y3+ ions induced notable transformations in the structural, optical, microstructural, magnetic, and photocatalytic properties of CoFe 2 O 4 nanoparticles. Analytical techniques such as x-ray diffraction, fourier transform infrared spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, photoluminescence, transmission electron microscopy, vibrating sample magnetometry, and electron paramagnetic resonance spectroscopy were employed to investigate these effects. The investigation into the photocatalytic degradation of methylene blue (MB) under ultraviolet light irradiation was carried out. The influence of distinct elemental compositions, catalyst quantities, irradiation durations, and initial methylene blue concentrations on the decolorization process was assessed. [ABSTRACT FROM AUTHOR]

Using the Heyd–Scuseria–Ernzerhof hybrid functional method, we present a systematic study on the electronic and magnetic properties of Fe-doped antimonene. One and two Fe substitutions in an 8 × 8 supercell of antimonene are examined, and the thermodynamic and kinetic stability of Fe dopants in antimonene is thoroughly addressed. Results show that with a single Fe dopant in antimonene, the spins on the dopant are parallel to the induced spins on the surrounding Sb atoms via the hybridization between Sb 5p and Fe 3d orbitals, giving rise to ferromagnetism. Two Fe dopants in antimonene tend to stay at the substitutional sites next nearest to each other via the strong attraction, leading to the formation of the Fe-Sb-Fe cluster. With such a cluster, apart from the p-d hybridization between Fe and the surrounding Sb atoms (like the case of a single Fe dopant), two Fe atoms are found to couple ferromagnetically to each other via the mediation of the common nearest Sb atom. The ferromagnetic mechanisms between two Fe dopants are discussed and analyzed. This work offers useful theoretical guidance for promoting the applications of antimonene to spintronics. [ABSTRACT FROM AUTHOR]

The processing route of Sm2Fe17 carbides is shorter than that of nitrides, which can potentially be used for cost-effective mid-performance magnets' production. The magnetic properties of Sm2Fe17Cx compounds can be controlled at the annealing step, which allows them to be used for a variety of applications. In this work, X-ray diffraction (XRD) analysis, Mössbauer spectroscopy, scanning and transmission electron microscopy (SEM, TEM) and vibrating sample magnetometry (VSM) were used for characterization of the structure and magnetic properties of Sm2Fe17Cx compounds. The powder samples were prepared by high-energy ball milling of Sm2Fe17 mixtures with carbon nanotubes (CNT) or graphite with subsequent annealing. The formation of Sm2Fe17Cx compounds after annealing was followed by the formation of α-Fe and amorphous Sm2O3. The hyperfine field values of Fe atoms of all the Sm2Fe17 lattice sites increased by 12% on average after annealing that was caused by carbon diffusion. The coercivity of the samples peaked after annealing at 375 °C. The samples with CNT demonstrated an increase of up to 14% in coercivity and 5% in specific remanence in the range of 250–375 °C annealing temperatures. [ABSTRACT FROM AUTHOR]

This review reports the latest trends in the ceramic composite matrix used for the magnetoelectric (ME) effect. In the last few years, ME composite has become the center of attraction for use in various electrically and magnetically coupled devices. The growth and use of electronic components everywhere have propulsively accelerated the exploration of self-powered electronic and sensor network devices. ME is a feasible technique for addressing difficulties of traditional batteries such as short life span and frequent recharge difficulties. Self-charging multiferroic components have been found for the constant working of mobile electronics that use multiferroic composites in response to magnetoelectric energy transformation. Researchers have rigorously studied the rigid and flexible magnetoelectric composites for their suitability in applications. This paper gives a comparative study between rigid and flexible magnetoelectric composites based on their properties and provides knowledge about the materials for such types of composites. It reviews the latest polymer-based ME materials as well as the related fabrication and polarization methods. The review finally encapsulates the applications in biomedicine, ranging from mechanical energy harvesters to sensors and actuators. [ABSTRACT FROM AUTHOR]

A tremendous amount of research has witnessed the exploration of two-dimensional (2D) materials with intrinsic ferromagnetism and diverse physical properties. However, the low Curie temperature and deficient magnetic anisotropy hinder their practical applications in nanoscale spintronics. Based on first-principles calculations, we propose a new family of 2D ternary transition metal tellurides, CrX2Te4 (X = Al, Ga, and In), with both structural and magnetic stabilities at room temperature. Our calculations demonstrate that the 2D CrX2Te4 crystal exhibits the intrinsic 100% spin-polarized half-metallic feature with spin-up metallic and spin-down semi-conducting properties. With the remarkable magnetic moment of 4 μB per Cr atom, both 2D CrAl2Te4 and CrGa2Te4 crystals perform robust ferromagnetism with the out-of-plane magnetic anisotropy, while the 2D CrIn2Te4 crystal prefers the in-plane easy magnetization axis. The Monte Carlo simulation based on the 2D Heisenberg model shows that the critical Curie temperatures of the 2D CrAl2Te4, CrGa2Te4, and CrIn2Te4 crystals could reach 466, 431, and 536 K, respectively. Moreover, the magnetic exchange strength and magnetic anisotropy could be further enhanced by the in-plane biaxial strain. The novel electronic and magnetic features promote 2D CrX2Te4 (X = Al, Ga, and In) crystals as a new family of two-dimensional intrinsic ferromagnetic materials for next-generation advanced spintronics. [ABSTRACT FROM AUTHOR]

Flat-band systems with strongly correlated electrons can exhibit a variety of phenomena, such as correlated insulating and topological states, unconventional superconductivity, and ferromagnetism. Rhombohedral multilayer graphene has recently emerged as a promising platform for investigating exotic quantum states due to its hosting of topologically protected surface flat bands at low energy, which have a layer-dependent energy dispersion. However, the complex relationship between the surface flat bands and the highly dispersive high-energy bands makes it difficult to study correlated surface states. In this study, we introduce moiré superlattices as a method to isolate the surface flat bands of rhombohedral multilayer graphene. The observed pronounced screening effects in the moiré potential-modulated rhombohedral multilayer graphene indicate that the two surface states are electronically decoupled. The flat bands that are isolated promote correlated surface states in areas that are distant from the charge neutrality points. Notably, we observe tunable layer-polarized ferromagnetism, which is evidenced by a hysteretic anomalous Hall effect. This is achieved by polarizing the surface states with finite displacement fields. Rhombohedral multilayer graphene has emerged as an exciting solid-state platform for studying correlated electron physics. Here, the authors demonstrate field-tunable layer-polarized ferromagnetism and isolated surface flat bands engineered with a moiré potential. [ABSTRACT FROM AUTHOR]

The dynamical response of a quantum spin liquid upon injecting a hole is a pertinent open question. In experiments, the hole spectral function, measured momentum-resolved in angle-resolved photoemission spectroscopy (ARPES) or locally in scanning tunneling microscopy (STM), can be used to identify spin liquid materials. In this study, we employ tensor network methods to simulate the time evolution of a single hole doped into the Kitaev spin-liquid ground state. Focusing on the gapped spin liquid phase, we reveal two fundamentally different scenarios. For ferromagnetic spin couplings, the spin liquid is highly susceptible to hole doping: a Nagaoka ferromagnet forms dynamically around the doped hole, even at weak coupling. By contrast, in the case of antiferromagnetic spin couplings, the hole spectrum demonstrates an intricate interplay between charge, spin, and flux degrees of freedom, best described by a parton mean-field ansatz of fractionalized holons and spinons. Moreover, we find a good agreement of our numerical results to the analytically solvable case of slow holes. Our results demonstrate that dynamical hole spectral functions provide rich information on the structure of fractionalized quantum spin liquids. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) magnetic materials are of not only fundamental scientific interest but also promising candidates for numerous applications. However, so far only a few intrinsic magnets with long-ranged order down to the 2D limit have been experimentally established. Here, we report that the intrinsic 2D ferromagnetism can be realized in van der Waals (vdW) Fe3GaTe2 nanoflake down to monolayer. By measuring the Hall resistance and magnetoresistance, we demonstrate that the Fe3GaTe2 monolayer exhibits 2D hard ferromagnetism with record-high Cure temperature (Tc) of 240 K for the monolayer of known intrinsic ferromagnets. Both of square-shaped hysteresis loops with near-vertical jump in anomalous Hall effect (AHE) and the negative magnetoresistance (NMR) behavior with an applied out-of-plane magnetic field reveal robust perpendicular magnetic anisotropy (PMA) in Fe3GaTe2 nanoflakes down to the monolayer limit. Furthermore, we find the intrinsic mechanism that stems from the Berry curvature of electronic bands dominates AHE of nanoflakes in the low temperature range. Our results not only provide an excellent candidate material for next-generation spintronic applications, but also open up a platform for exploring physical mechanisms in 2D ferromagnetism. [ABSTRACT FROM AUTHOR]

The phase-pure magnetic semiconducting Fe x/2 Ni x/2 Sn 1-x O 2 solid solutions with x = 0.03, 0.06, 0.09, and 0.12, were prepared by a cost-effective room-temperature one-step co-precipitation method. XRD peak red-shift reveals lattice compression due to the doping of low/similar ionic radii of Fe3+, Ni3+, and Ni2+ in the Sn4+ lattice, which is also confirmed by the EPR results. Maximum entropy method (MEM)-based electronic structure confirmed interstitial charge accumulation of 6.79 % and 6.05%, forming non-nuclear maxima in 3% and 12% doping systems, respectively, which reduces considerably the ferromagnetism. In addition, pure polar covalent apical and equatorial (Fe/Ni/Sn) – O bonding without interstitial charge accumulation is a key factor for maximum ferromagnetism. A perfect-fitting of the pair distribution function (PDF) and its correlation to charge accumulation at interstitial and regular lattice points in comparison with MEM results provides hope in PDF using low-Q XRD data. The samples with 9% and 6% dopants showed soft ferromagnetism with magnetization (0.0416 and 0.0372) emu/g respectively, which are helpful for magnetic semiconducting applications. The ferromagnetic and antiferromagnetic coupling between interstitial charges' local magnetic domains causes positive exchange anisotropy (exchange bias) in 3% and 12% compositions. The novel and empirical correlation between magnetism and the MEM-based electronic structure is the highlight of this study. [ABSTRACT FROM AUTHOR]

Micrometer-sized polycrystalline anatase particles are widely used in materials and life sciences, serving as essential components in photocatalytic materials. The ability to tailor their composition, shape, morphology, and functionality holds significant importance. In this study, we identified and examined the non-destructive route of Copper(II) implantation at the surface of polycrystalline TiO2. The [Cu(en)(Im)2]2+ complex ion demonstrated a remarkable affinity to concentrate and bind with the semiconductor's surface, such as anatase, forming a surface-bound adduct: ≡TiO2 + [Cu(en)(Im)2]2+ → ≡TiO2//[Cu(en)(Im)2]2+. The misalignment of Fermi levels in TiO2//[Cu(en)(Im)2]2+ triggered electron transfer, leading to the reduction of the metal center, releasing Copper(I) in the process. Although less efficient, the released Copper(I) encountered a highly favorable environment, resulting in the formation of the surface complex TiO2:CuIIsc. The implanted Cu(I) was converted back into Cu(II) due to re-oxidation by dissolved oxygen. The penetration of the metal ion into the surface level of the polycrystalline TiO2 lattice was influenced by surface residual forces, making surface grafting of the Cu(II) ion inevitable due to surface chemistry. FTIR, UV–vis, Raman, XRD, EPR, and surface morphological (SEM, EDAX, and HRTEM) analyses identified the typical surface grafting of the Cu(II) cluster complex on the anatase surface matrix. Moreover, the XRD results also showed the formation of an impure phase. The TiO2 polycrystalline materials, modified by the incorporation of copper complexes, demonstrated an enhanced visible-light photocatalytic capability in the degradation of Rhodamine B dye in aqueous solutions. This modification significantly improved the efficiency of the photocatalytic process, expanding the applicability of TiO2 to visible light wavelengths. These studies open up the possibility of using copper complexes grafted on metal oxide surfaces for visible-light active photocatalytic applications. Moreover, this investigation not only showcases the improved visible-light photocatalytic behavior of copper-modified TiO2 polycrystalline materials, but also underscores the broader implications of this improvement in the advancement of sustainable and efficient water treatment technologies. [ABSTRACT FROM AUTHOR]

A method for solving a self-consistent boundary value problem for the linearized Usadel equation is proposed. The method makes it possible to find the sample-normalized distribution of the superconducting order parameter and the critical temperature as functions of the problem parameters and to solve relatively complex spatially inhomogeneous problems, e.g., superconducting heterostructures containing inhomogeneous magnetic layers. Within this approach, layered structures containing superconducting and domain-split ferromagnetic layers are considered. The theory is compared with experiment for the Fe 20 Å/V 340 Å/Fe 8 Å/Cr/Fe 8 Å system. [ABSTRACT FROM AUTHOR]

Copyright of Materials & Technologies / Materiali in Tehnologije is the property of Institute of Metals & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, using variational methods and critical point theory we establish the existence of multiple solutions for a class of elliptic equations on Carnot groups depending on one real positive parameter and involving a subcritical nonlinearity. Some recent results are extended and improved. [ABSTRACT FROM AUTHOR]

chemical attributes. The specific domain within technology referred to as spintronics, encompasses the realm of spin transport electronics. Spintronics delves into the electron spin, its inherent magnetic moment and fundamental charge, and the manipulation of these intrinsic characteristics to develop solid-state devices. In metallic systems, spintronics encloses phenomena like spin-charge coupling, which includes ferro- and ferrimagnetic materials, giant and colossal magnetoresistive materials, and metallic spins. Among the most versatile materials in the evidence of exotic properties, one of the most representative families is the so-called perovskites, widely studied in recent years including their properties in solar cell technology. Here, we present some crystallographic, compositional, morphological, optical, and magnetic attributes of the Ca2TiFeO6 double perovskite material, synthesized by the standard solid-state reaction method from high-purity precursor oxides. Rietveld refinement of experimental X-ray diffraction data revealed that this material crystallizes in a monoclinic perovskite-type structure with alternating ordering of Ti-Fe cations along the three crystallographic axes. The strongly granular surface character of the Ca2TiFeO6 materials was observed in the images from a scanning electron microscope; the electron X-ray energy dispersive spectra revealed a close match of sample composition to that expected from their chemical formula. The diffuse reflectance spectrum showed the semiconductor feature of the material with a 1.02 eV bandgap. The magnetic characterization in the 50 K < T < 335 K regime and the applied fields up to 1 kOe showed the ferromagnetic response of the material over the entire temperature range measured. These properties are promising in the spintronics industry for devices where the same material serves to process, record, read, and erase information as in the spin transistors.