Search

Recent studies have shown that layered compound EuCd2As2 could exhibit diverse topological states depending on the different magnetic structures, such as Weyl semimetal, Dirac semimetal, topological insulator, etc. In order to further study the interplay between magnetism and topology of EuCd2As2, it is necessary to figure out its magnetic structure. Here, by magnetization (M) measurements and negative magnetostriction (λ) along the [001] direction measured by scanning tunneling microscope on EuCd2As2 single crystals, we observe field-induced metamagnetic phase transition from A-type antiferromagnetic (AFM) ground state to field-polarized state, with canted AFM (CAFM) state in between. Magnetization and magnetostriction are more sensitive to the in-plane field than the out-of-plane field, indicating the magnetic moments lying in the ab plane. The absence of abrupt jump on M-H and λ-H curves demonstrates the phase transition is a second-order type. In CAFM state, M increases linearly with the field and λ is proportional to M 2 . Tunneling conductance spectra show the field-induced evolution of the electronic density of states. Our results provide experimental evidence for understanding the magnetic structure of EuCd2As2.

Magnetism has revolutionized important technologies, and continues to bring forth new phenomena in emergent materials and reduced dimensions. Here, using first-principles calculations, we demonstrate that the already-synthesized two-dimensional (2D) Ni-tetracyanoquinodimethane (Ni2(TCNQ)2) lattice is a stable ferromagnetism material with multiple spin-polarized Dirac cones. The conical bands in proximity of the Fermi level can be tuned by external tensile strain and show the fourfold degenerate electronic states at the critical tensile strain of ∼2.35%, whose energy dispersion is consistent with 2D Cairo pentagonal lattice. In addition, spin-orbital coupling can open a band gap at the Dirac point of A, leading to topologically nontrivial electronic states characterized by the non-zero Chern number and the edge states of nanoribbon. Our results offer versatile platforms for the realization of massless spintronics with full-spin polarization in 2D Cairo pentagonal Ni2(TCNQ)2 Lattice.

Molecules with multifunctional properties are of immense interest in hybrid materials, while challenges still existed because of the limited compatibility of multiple functionalities in a single system. In this work, a series of metal-organic complexes were synthesized and characterized under the assembly of electron donor phosphonate, electron acceptor polypyridine ligand and spin carrier rare earth ions. All the compounds exhibited remarkable and reversible responses with photochromism and photomodulated fluorescence, originated from photogenerated radicals via electron transfer from phosphonates to polypyridine ligands. For the Dy analog, slow magnetic relaxation was observed at cryogenic temperature, indicating the single-molecule magnetic behavior. Furthermore, photogenerated radicals could enhance the proton conductive behavior, with about 2 times larger in magnitude after light irradiation for Dy and Y compounds. The introduction of photoluminescence, magnetism and proton conduction into metallic phosphonates can provide potential applications for photochromic materials.

Research on two-dimensional (2D) materials is one of the most active fields in materials science and nanotechnology. Among the members of the 2D family, layered hydroxides (LHs) represent an exceptional case of study due to their unparalleled chemical versatility which allows the modulation of their physicochemical properties at will. Nowadays, LHs based on earth-abundant metals are key materials in the areas of energy storage and conversion, hybrid materials or magnetism. ɑ-Co hydroxides (Simonkolleite-like structures) are promising phases with tuneable electronic and magnetic properties by ligand modification. However, even in the simple case of ɑ-CoII hydroxychlorides, the preparation of well-defined large 2D crystals is not straightforward, hindering the development of fundamental studies. Herein, we present the synthesis of 2D hexagonal crystals with outstanding size-thickness relationship (diameter > 5 μm and thickness of 20 ± 7 nm) by a simple homogeneous synthesis taking place at room temperature. In structural terms, no differences are observed between our layered materials and those obtained hydrothermally. However, dynamic susceptibility measurements alert about different arrangements of the magnetic sublattices, which have been rationalized with structural DFT calculations. This work provides an extremely easy bottom-up method to obtain high-quality 2D crystals based on ɑ-CoII hydroxides, paving the way for the development of fundamental studies and applications. PNICTOCHEM 804110 (G.A.) PID2019-111742-GA-I00 CIDEGENT/2018/001

BaTiO3 ceramics doped with double perovskite Sr2KMoO6 (BT-SKM) are fabricated via solid-state reaction technology. The effects of SKM dopants on the structure, band gap and electrical/magnetic properties of BT are systematically studied. XRD and Raman spectra analysis show polycrystalline perovskite structure of the samples, which confirms the structural changes. With the addition of SKM dopants, the grain size of the samples decreases significantly. The band gaps of doped BT samples reduce, and the minimum band gap of BT-SCM is 1.77 eV, which is apparently reduced compared with the band gap of pure BT of 3.22 eV. However, the ferroelectric properties are weakened in samples doped with SKM. This ascribes to the introduction of more oxygen vacancies by dopants, which impedes the switching of domains, resulting in deterioration of ferroelectric properties. Furthermore, ferromagnetism of BT-SNM is observed, which may be attributed to the long-range exchange interaction between Ni2+ ions and oxygen vacancies. These results reveal the potential applications of these perovskite oxides in photovoltaic and memory devices.

In this study, the structural, morphological, and magnetic properties of hydrothermally synthesized Co0.5Ni0.5BixFe2-xO4 (x=0.00–0.10) nanosized spinel ferrites, (CoNiBiFO (x=0.00–0.10) NSFs), were investigated. The formation of CoNiBiFO NSFs phase was confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the morphology of the NSFs. Magnetization revealed that undoped Co0.5Ni0.5Fe2O4 and Co0.5Ni0.5BixFe2-xO4 NSFs (except with x = 0.04) exhibit ferrimagnetic magnetism at 300 K. Only the hysteresis loops recorded from Co0.5Ni0.5Bi0.04Fe1.96O4 NSFs have superparamagnetic characteristics. Mixed Co0.5Ni0.5Fe2O4 NSFs have maximum remnant magnetization (Mr) of 23.5 emu/g, maximum saturation magnetization (MS) of 63.38 emu/g, and maximum magneton number (nB) 2.66 μB. However, Co0.5Ni0.5Bi0.04Fe1.96O4 NSFs have minimum MS of 28.25 emu/g and minimum nB as 1.22 μB among Bi3+ doped and undoped samples. The coercivity (HC) of undoped Co0.5Ni0.5Fe2O4 NSFs is 656 Oe. However, the Bi3+ ion-doped samples have a wide range of HC values between 101 Oe and 1038 Oe. The squareness ratios are in the range of 0.092–0.418 and multi-domain structure is assigned for all types of samples. The measured positive exchange bias (HE) magnitudes are 268 Oe and 290 Oe, respectively. Hysteresis loops recorded at 10 K proved that the products are ferrimagnetic. These coercivities showed that all the samples are magnetically harder at low temperatures. Positive HE values of 165 Oe and 297 Oe were measured from the nanoparticles (NPs) with x = 0.08 and x = 0.10 at 10 K. The SQR of the Co0.5Ni0.5Bi0.04Fe1.96O4 sample at 10 K is almost equal to the critical value of 0.5, and a single domain structure with uniaxial symmetry can be attributed for this sample. The other samples have SQRs in the range of 0.632–0.782 and multi-domain wall structure is assigned for them at 10 K.

This work reports the fabrication of magnetic polymer dimers with controlled surface anisotropy. The fabrication process involves the preparation of magnetite (Fe3O4) magnetic clusters with strong magnetism, followed by their surface modification, dispersion polymerization while using them as seeds, multilayer shell formation via layer-by-layer deposition, and polymer core swelling. The interplay between the swelling and multilayer shells generates pressure inside the multilayer-deposited, magnetic polystyrene (PS) spheres, forming structurally anisotropic dimers with single PS protrusions anchored on the multilayer surfaces within minutes. The use of titania precursor and different swelling agents, along with the change in the composition of the multilayer shell, enables the introduction of different surface anisotropies, such as the surface-charge anisotropy, anisotropic hydrophilicity/hydrophobicity, and material composition anisotropy, to the dimers. The strong magnetic response of the dimers, attributed to the magnetic cluster seeds, in combination with the surface-charge and material composition anisotropies allows a rapid magnetic recovery and an excellent reusability, enabling their application to 20-cycled reduction of 4-nitrophenol (4-NP) and methylene blue (MB) without loss of catalytic activity. Furthermore, the anisotropic hydrophilicity/hydrophobicity makes the dimers potentially useful as solid surfactant to stabilize immiscible oil–water mixture.

Mn3O4 Hausmannite thin films supported on (Cu, Ag, Au) coinage metals have been studied for the first time by means of DFT calculations. The different lattice and ionic match at the interface with the metal support gives raise to different type of interactions. On copper, Mn3O4 (1 1 0) films subject to tensile strain strongly adhere to the metal surface, undergoing a remarkable structural change. On the contrary, Mn3O4 (0 0 1) films adhere weakly to Cu (1 1 1) and Au (1 1 1), where the structural match is unfavourable, and strongly on Ag(1 0 0), where the lattice is commensurate and epitaxial films can grow. A negative charge flow from the support to the film is reported, in particular when strong bonds at the interface are formed. This causes the reduction of the film and the subsequent increase in the magnetic moments of some metal ions in the octahedral sublattice. The reduced centres are prevalently located at the film surface. The ferrimagnetic ordering is different in supported films exposing the (0 0 1) or the (1 1 0) face.

It is still an open debate whether the 1:5H cell boundaries (CBs) or the intersections of 1:3R platelets and 1:5H CBs are the strong pining sites for the cellular nanostructured 2:17-type Sm-Co-Fe-Cu-Zr high temperature permanent magnets despite that they have been widely applied in advanced industries since 1970s. Herein, through tuning the volume fraction of Zr-enriched 1:3R platelets by varying the second-step aging time, the pinning behavior in a model magnet Sm25Co44.9Fe21.5Cu5.6Zr3.0 (wt%) was investigated. The results show that the volume fraction of 1:3R platelets can be effectively enlarged without changing the cell size (i.e. the volume fraction of CBs) by extending the aging time at 400 °C. Microscopic TEM characterizations combined with macroscopic magnetic measurements reveals that the locally thickened 1:3R platelets after long-term second-step aging reduce the effective pinning area by interrupting the magnetic domain walls at CBs, weakening the average pinning strength and the coercivity of the magnet. Consequently, our work supports that the 1:5H CBs act as the dominating pinning sites instead of the intersections of 1:3R platelets and 1:5H CBs, which may provide an important insight towards understanding the hard magnetism of pinning-controlled permanent magnets.

Summary Magnetoelectric (ME) coupling has gradually developed into one of the core means of advancing ultralow-power memory, logic, and sensor technologies. Among various strategies, magneto-ionic control of magnetism based on mechanisms such as redox, intercalation/deintercalation, and charge accumulation can be achieved in ion battery or capacitor systems. In this work, we demonstrate an ME effect originating from the spin capacitance, combining the advantages of intercalation batteries and supercapacitors. Giant, fast, and reversible modulations on the saturation magnetization of ferromagnets are achieved by Li ion motion across the ferromagnet/lithionic conductor interfaces at no more than 1 V. Furthermore, the magnetic evolution driven by the conversion reaction between FeO and Fe over a larger voltage range demonstrates ferromagnetic ordering of the FeO surface. These findings not only open new perspectives for developing high-performance magneto-ionic devices but also are crucial to designing spintronic devices composed of iron and oxide multilayer structures.

Summary Lanthanoid chelating tags (LCTs) are widely used for advanced paramagnetic NMR of biomacromolecules. The magnitude of their induced pseudocontact shifts (PCSs) and residual dipolar couplings (RDCs) depends critically on the anisotropy of the magnetic susceptibility tensor, which is usually determined by the resonances of the conjugated protein, inevitably reducing the effect by motional averaging. Here, for the first time, we present the intrinsic anisotropy parameters for the full lanthanoid series determined experimentally from resonances on the ligand itself. The strongly shifted proton spectra could only be assigned by extensive, site-specific isotope labeling. The extremely large anisotropies obtained deliver an upper limit for future PCS applications. To our great surprise, at least at room temperature, we observed an unprecedented correlation between the oblate or prolate f-electron distribution of the lanthanoid and the orientation of the main magnetic axis as well as the size of the magnetic anisotropy.

The increasing electromagnetic hazards including electromagnetic interference and electromagnetic pollution, which were stemmed from massive usage of electromagnetic technology, have triggered widespread concerns. To cope with this challenge, electromagnetic wave absorbing materials with high performance are greatly needed. Composite construction has been widely applied in electromagnetic (EM) wave absorbing materials to achieve high permittivity, high permeability and impedance matching. However, high-temperature stability, oxidation and corrosion resistance are still unignorable issues. Herein, high entropy hexaborides/tetraborides (HE REB6/HE REB4) composites with synergistic dielectric and magnetic losses were designed and successfully synthesized through a one-step boron carbide reduction method. The five as-prepared (Y0.2Nd0.2Sm0.2Eu0.2Er0.2)B6/(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)B4, (Y0.2Nd0.2Sm0.2 Er0.2Yb0.2)B6/(Y0.2Nd0.2Sm0.2Er0.2Yb0.2)B4, (Y0.2Nd0.2Eu0.2Er0.2Yb0.2)B6/(Y0.2Nd0.2Eu0.2Er0.2Yb0.2)B4, (Nd0.2Sm0.2Eu0.2Er0.2Yb0.2)B6/(Nd0.2Sm0.2Eu0.2Er0.2Yb0.2)B4 and (Y0.2 Sm0.2Eu0.2Er0.2Yb0.2)B6/(Y0.2Sm0.2Eu0.2Er0.2Yb0.2)B4 contain two phases of HE REB6 and HE REB4. Among them (Y0.2Nd0.2Sm0.2Eu0.2 Er0.2)B6/(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)B4 (HE REB6/HE REB4-1) and (Y0.2Nd0.2Sm0.2Er0.2Yb0.2)B6/(Y0.2Nd0.2Sm0.2Er0.2Yb0.2)B4 (HE REB6/HE REB4-2) exhibit excellent EM wave absorption properties. The optimal minimum reflection loss (RLmin) and effective absorption bandwidth (EAB) of HE REB6/HE REB4-1 and HE REB6/HE REB4-2 are –53.3 dB (at 1.7 mm), 4.2 GHz (at 1.5 mm) and –43.5 dB (1.3 mm), 4.2 GHz (1.5 mm), respectively. The combination of conducting HE REB4 with magnetism into HE REB6 as a second phase enhances dielectric and magnetic losses, which lead to enhanced EM wave absorption performance. Considering superior high-temperature stability, oxidation and corrosion resistance of HE REB6 and HE REB4, HE REB6/HE REB4 composite ceramics are promising as a new type of high-performance EM wave absorbing materials.

In this study, we proposed a new method to prepare yttrium iron garnet/yttrium iron garnet (YIG/YIG) functional joint via in-situ synthesis of novel Co2FeO4 needle-like phases. It is found that the formation of the Co2FeO4 needle-like phases was controlled by “two-step heterogeneous nucleation”: (i) CoO nanoparticles acted as the preliminary heterogeneous nucleation particle, reacting with O2 to form Co3O4 phase; (ii) The surface of Co3O4 phase acted as the subsequent heterogeneous nucleation interface, atoms stacked along the (220) crystal plane of Co3O4 to form Co2FeO4 phase. Fe3+ diffused into the glass matrix which is rich in O2−, participating in the reaction with Co3O4 and CoO. The Co2FeO4 nuclei grew into needle-like phases along the [001] orientation. The Co2FeO4 needle-like phases exhibited favourable mechanical property and magnetism according to the nanoindentation and magnetic force microscopy (MFM) analysis. And the shear strength of YIG/YIG joint reinforced by Co2FeO4 needle-like phases could reach 72 MPa. The investigation supplies a new synthetic idea of Co2FeO4 magnetic needle-like phases, which has significant application potential for the structural and functional integration in electromagnetic field.

Designing one-dimensional (1D) magnetic-carbon composites microwave absorbers is a promising strategy that can meet the current demand for high-performance microwave absorption (MA) materials. In this work, hierarchical structured Fe3O4/Fe@C@MoS2 nanofibers were successfully obtained via a simple three-step method. 1D Fe3O4/Fe@C nanofibers were fabricated through electrospinning technology and in-situ polymerization followed by carbonization and reduction in H2/N2 atmosphere. MoS2 nanosheets grew irregularly on the surface of 1D Fe3O4/Fe@C nanofibers to form the flower-like structure. The morphology, composition and magnetism of samples were systematically investigated. Furthermore, electromagnetic characteristics and MA properties of Fe3O4/Fe@C nanofibers and Fe3O4/Fe@C@MoS2 nanofibers were compared. The minimum reflection loss (RLmin) of Fe3O4/Fe@C@MoS2 nanofibers could reach −53.79 dB at 11.12 GHz and the corresponding absorption bandwidth (RL

In order to efficiently explore the nearly infinite composition space in multicomponent solid solution alloys for reaching higher mechanical performance, it is important to establish predictive design strategies using computation-aided methods. Here, using ab initio calculations we systematically study the effects of magnetism and chemical composition on the generalized stacking fault energy surface (γ-surface) of Cr-Co-Ni medium entropy alloys and show that both chemistry and the coupled magnetic state strongly affect the γ-surface, consequently, the primary deformation modes. The relations among various stable and unstable stacking fault energies are revealed and discussed. The present findings are useful for studying the deformation behaviors of Cr-Co-Ni alloys and facilitate a density functional theory based design of transformation-induced plasticity and twinning-induced plasticity mechanisms in Cr-Co-Ni alloys.

Despite being difficult to identify, extremely dilute oxygen vacancies have been widely reported to play an important role in enhancing magnetism in ZnFe2O4. The mechanisms underlying this enhanced magnetism have not been well understood for a long time and remain controversial because the formation of oxygen vacancy-rich ZnFe2O4 can be accompanied by changes in the chemical/physical characteristics, especially the composition, particle size, surface morphology and cation distribution, which can significantly affect the magnetization. An open and important question is whether and to what extent the enhanced magnetization can be attributed only to oxygen vacancies. In this study, the relationship between the magnetization and oxygen vacancies in ZnFe2O4 was definitively determined by using a carefully designed “shake-and-heat” treatment to prepare vacancy-rich samples while keeping the other crystal/surface parameters constant. Compared to the nearly vacancy-free paramagnetism samples, the vacancy-rich samples exhibited a higher magnetization of approximately 5 emu/g at both 300 K and 2 K. The Fe3+-O2--Fe3+ superexchange paths broken by oxygen vacancies then resulting in the Fe3+-Fe3+ ferromagnetism configuration. Meanwhile, the oxygen vacancy is highly diluted then the ferromagnetism configuration is confined in a single super-cell, favoring a short-range magnetic ordering at room temperature. The concentration of oxygen vacancies was calculated to be 0.68% by magnetization measurement. Our results may shed a light on how oxygen vacancies affect magnetism.

In this paper, a simple, reproducible and cost-effective solid-state reaction sintering process is developed to fabricate (K0.5Na0.5)NbO3-xBaNi0.5Nb0.5O3-δ (KNN-xBNN) ceramics with a narrow bandgap and room-temperature ferromagnetism. Here, we report a systematic investigation of the influence of the BaNi0.5Nb0.5O3-δ (BNN) concentration on the properties of KNN-xBNN ceramics. All ceramics form orthorhombic perovskite structures with a space group Amm2 and a weak peak at the wavelength of 550 cm−1 that is characteristic of the pillow shoulder of the orthorhombic phase. KNN-xBNN ceramics with x between 0.02 and 0.08 have a narrow bandgap of about 2.5 eV—much smaller than the 3.5 eV of its parent (K0.5Na0.5)NbO3 (KNN) ceramic—which is attributed to Ni2+-oxygen vacancy combinations (Ni2+-VO) raising the valence electron energy level of the KNN ceramic. Furthermore, doping BNN into KNN ceramics can significantly convert the magnetism from diamagnetism to ferromagnetism and the component of x = 0.08 achieves both maximum saturation magnetisation intensity (14 memu/g) and minimum coercive magnetic field (80 Oe). Our findings provide a systematic insight into the bandgap tunability and ferromagnetism induction at room temperature in lead-free perovskite KNN-xBNN ceramics, as well as demonstrate their potential applications in perovskite solar cells and multiferroic devices.

A low-cost, collectable, and efficient material is essential for adsorbing water pollution, such as dyes and heavy metal ions pollution. In this work, we proposed a novel strategy for the preparation of an efficient and collectable magnetic aerogel as adsorbent for dye. The magnetic aerogels were prepared from sodium carboxymethylcellulose (CMC) hydrogel using citric acid (CA) as the crosslinker, followed by vacuum freeze-drying technique to obtain aerogels. The effects of magnetic Fe3O4 nanoparticle contents on the adsorption properties of the aerogels were investigated. The results show that the as-prepared magnetic composite aerogels exhibit porous structure and display good adsorption and collectable performance for methylene blue (MB) in water with the removal rate of 97.5% in 6 h. The maximum compress strength and absorption capacity of the magnetic aerogel with 1 wt% Fe3O4 nanoparticle loading for MB is 0.13 MPa and 83.6 mg/g, respectively. Aerogels with Fe3O4 nanoparticles exhibited magnetism which enables the aerogels to easily collect. This excellent structure stability and collectability guarantees long-term integrity and floatability of the magnetic aerogels in water.

Liquid marbles may be traditionally formed by rolling a droplet on a bed of non-wetting particles resulting in encapsulation and stabilisation. Particles used in this process may range from nanometre to millimetre if handled with sufficient care. This method, however, runs the risk of droplet coalescence and is limited to non-wetting particles. Currently there exist some alternative methods of formulation including using electrostatics to either deliver a particle bed to the droplet or pull the droplet to the particles. The former has shown some promise in potential batch processes but is hindered by interparticle forces. Additional production methods include a form of blender, but this has shown to be unable to produce marbles of a narrow size distribution. Once formed, liquid marbles have demonstrated value as potential blood typing devices, as micro-reaction vessels due to the inherent barrier between the internal phase and the substrate whilst maintaining gas permeability, and as contaminant sensors. Liquid marbles also demonstrate a remarkable level of elasticity under compressive force and reduced evaporation rates when compared to bare water droplets, a function of the size and composition of the stabilising particles. In addition to this, liquid marbles have been proposed as actuators. Locomotion may easily be induced in these structures, using electrostatics, sound, magnetism or light depending on the particle/liquid combinations used in formation, and the environment of deployment. This review seeks to present and summarise recent advances in the field of liquid marble manufacture and methods for actuation. We also aim to highlight potential future avenues of further study within this arena.

The spinel ZnFe2O4 specimens were obtained via a hydrothermal and a ceramic method, respectively, and their structural and magnetic properties were comparatively studied. It was found that all the specimens exhibited a single-phase and mixed spinel structure. The magnetism of specimens synthesized via the hydrothermal method is obviously greater than that of specimen prepared via the ceramic method. This can be ascribed to the occupancy of Fe ions resulted from the loss of Zn during the hydrothermal process.

A novel imaging materials based on bi-functional Fe3O4@MOO3-x@YF3:Yb/Er nanoparticles (NPs) with strong up-conversion luminescence and magnetic properties was designed and synthesized by inlaying MOO3-x with localized surface plasmon resonance (LSPR) and ferromagnetic property in the bi-functional Fe3O4@YF3:Yb/Er NPs. The morphology, structure and properties of Fe3O4@MOO3-x@YF3:Yb/Er NPs are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), photoluminescence (PL) spectra, UV–Vis-NIR spectrophotometer and superconducting quantum interference devices (SQUID). It was found that the experimental conditions (reaction temperature, reaction time, the mass ratio of core:shell and oxygen pressure in heat treatment) have a certain effect on the oxygen defect concentration of the MOO3-x interlayer. XRD also showed the crystal structure of Fe3O4, Fe3O4@MOO3-x and Fe3O4@MOO3-x@YF3:Yb/Er NPs. The SEM and TEM results showed that the average grain size of the prepared NPs were 200 nm. The SQUID and PL results showed that the Fe3O4@MOO3-x@YF3:Yb/Er NPs have stronger magnetism (14.3 emu/g) and excellent up-conversion luminescence performance (the emission peak at 525 nm is nearly 20 times higher than the corresponding emission intensity of the Fe3O4@YF3:Yb/Er). The Fe3O4@MOO3-x@YF3:Yb/Er NPs can be easily used to magnetic resonance and fluorescence dual-mode image-guided visual delivery drug and also increase the accurate diagnosis and treatment effect of malignant tumor.

Summary A fundamental part of characterizing any metal complex is understanding its electronic ground state, for which magnetometry provides key insight. Most uranium(IV) complexes exhibit low-temperature magnetic moments tending to zero, consistent with a non-degenerate spin-orbit ground state. However, there is a growing number of uranium(IV) complexes with low-temperature magnetic moments ≥1 μB, suggesting a degenerate ground state, but the electronic structure implications and origins have been unclear. We report uranium(IV)-oxo and -imido complexes with low-temperature magnetic moments (ca. 1.5–1.6 μB) and show that they exhibit near-doubly degenerate spin-orbit ground states. We determine that this results from the strong point-charge-like donor properties of oxo and imido anions generating pseudosymmetric electronic structures and that traditional crystal field arguments are useful for understanding electronic structure and magnetic properties of uranium(IV). This suggests that a significant number of uranium(IV) complexes might benefit from a close re-evaluation of the nature of their spin-orbit ground states.

We present convective instability analyses of the boundary-layer flows originated over cones (with half-angle ψ ≤ 9 0 ∘ ) rotating in an otherwise still conducting fluid. A uniform magnetic field (with magnetic strength parameter, m ≥ 0 ) is acting normally on the surface of each cone. In the non-magnetic case of cones, comparison of present results with existing experimental and theoretical studies lead *to propose that onset of instabilities may be attributed to crossflow (type I) modes and streamline curvature (type II) modes for broad cones (with ψ ≥ 4 0 ∘ ) and more slender cones (with ψ ≤ 1 5 ∘ ), respectively. For slender cones with half-angle ψ in the vicinity of 25° the presented results validate the hypothesis of centrifugal (type III) modes ( discovered by Garrett et al. (2014)). In the magnetic case, increasing magnetic strength m ∈ ( 0 , 11 ] considerably delays the onset of instabilities (due to both type I and type II modes) over each rotating cone with fixed ψ . The stabilising influence of magnetism is in agreement with the meagrely available theoretical studies for magnetic rotating disk case ψ = 9 0 ∘ . In addition, our results lead to suggest that streamline curvature mode over each cone with fixed half-angle ψ become sensitive with increasing m. A minimum m 0 ∈ [ 0 , 11 ] exists for each fixed half-angle ψ 0 ≤ 9 0 ∘ such that whenever m ≥ m 0 the onset of instabilities (in the sense of minimum critical Reynolds numbers) over every cone with half-angle ( ψ ≤ ψ 0 ) are commenced by type II mode instead of type I mode whilst the aforementioned conjecture of stabilising effect of magnetism is not violated in the considered range of parameters. Under non-stationary vortices assumption with magnetism, we show that crossflow modes travelling at around 75% of the cone surface are likely to be selected in applications where smooth and frictionless surfaces are used. This finding is in complete agreement with the non-magnetic case of rotating cone in existing studies.

Magnetoelectric (ME) materials have been attracting extensive attention due to their potential applications. It is important to realize strong ME effect in one single material at sufficiently high temperature, and thus substantial efforts in searching for ME materials with strong ME coupling together and a comprehensive understanding of the underlying mechanism is necessary. Herein we focus on the Mn-doped linear ME material Co4-xMnxNb2O9, in which a large electric polarization driven by magnetic field emerges below its Neel temperature TN, by presenting the detailed characterizations on the structure, magnetism, and ME effect. It is revealed that an increasing Mn substitution x allows largely enhanced TN and gradually suppressed ME coefficient αME. This ME coupling suppression is attributed to the weak spin-orbit interaction of Mn2+ with respect to Co2+. It is indicated that the Dzyaloshinskii-Moriya (DM) interaction plays an important role in the ME coupling. The measured largest αME is found in For Co0.8Mn3.2Nb2O9, reaching up to 9.9 ps/m at 10 K while the TN reaches up to 102 K, exceeding most of the linear ME materials that have been reported.

The influence of a high magnetic field (HMF) on the nucleation kinetics of paramagnetic aluminum and diamagnetic zinc melts has been investigated by differential thermal analysis (DTA). It is found that the application of an HMF increases the undercooling of pure aluminum and pure zinc at the same heating-cooling rates. Moreover, the quantitative analysis of activation energy calculated from the DTA results using the Kissinger method manifests that the HMF reduces the activation energy of pure aluminum and pure zinc. Regardless of magnetism, the nucleation frequency under an HMF is higher than that without an HMF. Furthermore, the increase in undercooling under the HMF is mainly attributed to the increase of the contact angle, calculated by the functional relationship between the cooling rate and undercooling. This result is consistent with the increase of the calculated nucleation work for pure aluminum and pure zinc. Additionally, the increase in undercooling caused by the HMF is partly ascribed to the magnetic field-induced suppression of thermal convection in the undercooled melt.

Nitridated iron is a promising material for potential applications in permanent magnets. Recent work on stabilization of nitridated iron in a foil form through nitrogen ion implantation and annealing motivates to study effect of thermal annealing on the surface of nitrogen-implanted iron. In this work, we show effect of annealing on chemical state and magnetism of nitrogen implanted epitaxial iron films. It is observed that nitrogen in the lattices only stays at the lower temperatures than 450 °C. In addition, significant reduction and lattice modification are taken placed, when the film is annealed at 450 °C. The increases of saturation magnetization and coercivity, where it is annealed at 450 °C, are likely to be triggered by reduction of oxygen contents at the surface and thinning of Fe2O3.

Introduction of magnetism in large-area monolayer graphene has captured much attention in the graphene community, owing to the potential applications in transistors, magnetic memory, spintronic devices, and so on. Here, we use graphene nanoribbons (GNRs) as reinforcing rebar to in situ reinforce large-area graphene, where the edges of graphene nanoribbons are found to be seamlessly welded with graphene sheet. Based on the GNR-reinforced graphene, Fe nanoparticles encapsulated by carbon nano-onions (CNOs) with controllable shell thickness are in situ grown on the surface to introduce efficient ferromagnetic phase to graphene by a facile and scalable method. When core-shell Fe@CNOs with thick shells are anchored, the hybrid film shows a strong p-doping electric behavior and an intriguing ferromagnetic property with remarkable remanence and coercivity in applied magnetic fields. The in situ growth of nanoscale Fe@CNOs on large-area GNR reinforced graphene will provide an additional avenue for the application of graphene-based films in flexible and transparent spintronic or magnetic electronics.

In this paper, the crystal structure, vacancy defect, local electron density and magnetic properties of Gd1-xCaxCrO3 (0 ≤ x ≤ 0.3) polycrystalline samples were investigated systematically. The crystal structural analyses show that all the samples are orthorhombic phase and a structural distortion happens around x = 0.3. Due to the formation of Cr4+ ions, both the lattice constant and the Cr–O bond length decrease. The results of positron annihilation spectrum reveals that the vacancy defect concentration increases and the local electron structure changes with the introduction of Ca2+ ions. The field-cooled (FC) and zero-field cooled (ZFC) curves of Gd1-xCaxCrO3 samples measured under H = 100 Oe exhibits negative magnetization characteristics due to the interaction between Gd3+ and Cr3+ ions, and the magnetism can be affected by the structural distortion.

In this study, we successfully prepared the Mg0.35Zn0.65Fe2O4 ferrite sample via standard solid-phase reaction and comprehensive studied its structure, magnetism, magnetocaloric effect and critical behavior. The XRD data refined by Rietveld technology confirms that the sample had a pure phase spinel structure. We conducted a magnetic study on the sample using SQUID and indicated that the sample’ ferromagnetic curie temperature Tc = 295 K, the paramagnetic curie temperature TP = 330 K, and the saturation magnetization can reach 125.41emu/g at an ultra-low temperature of 5 K. We tested the initial magnetization curve near the phase transition temperature (Tc) from ferromagnetic (FM) to paramagnetic states (PM) and produced an Arrott plot that confirmed the presence of a secondary phase transition. The sample’ maximum magnetic entropy change | Δ S M max | was 1.642 J/kg K and relative cooling power RCP was 185.2 J/kg in the external magnetic field H = 50 kOe. The critical parameter β, γ, δ, and TP were calculated using a Modified Arrott plot (MAP), Kouvel-Fisher (KF) plot and critical isotherm (CI) methods to study the type of magnetic order in the ferromagnetic state that corresponded to the magnetic state equation and mean field model. By analyzing the critical parameters, we obtained the ferromagnetic exchange integral constant J(r) ~ r−4.8498, which was between the 3D Heisenberg model and mean field models and very close to the mean field model, confirming that the long-range and short-range ferromagnetic orderly interactions coexisted with interaction phases and the long-range ferromagnetic orderly interaction dominates.

We have simulated the magnetic Bragg scattering in transmission electron microscopy in two antiferromagnetic compounds, NiO and LaMnAsO. This weak magnetic phenomenon was experimentally observed in NiO by Loudon (2012). We have computationally reproduced Loudon's experimental data, and for comparison we have performed calculations for the LaMnAsO compound as a more challenging case, containing lower concentration of magnetic elements and strongly scattering heavier non-magnetic elements. We have also described thickness and voltage dependence of the intensity of the antiferromagnetic Bragg spot for both compounds. We have considered lattice vibrations within two computational approaches, one assuming a static lattice with Debye-Waller smeared potentials, and another explicitly considering the atomic vibrations within the quantum excitations of phonons model (thermal diffuse scattering). The structural analysis shows that the antiferromagnetic Bragg spot appears in between (111) and (000) reflections for NiO, while for LaMnAsO the antiferromagnetic Bragg spot appears at the position of the (010) reflection in the diffraction pattern, which corresponds to a forbidden reflection of the crystal structure. Calculations predict that the intensity of the magnetic Bragg spot in NiO is significantly stronger than thermal diffuse scattering at room temperature. For LaMnAsO, the magnetic Bragg spot is weaker than the room-temperature thermal diffuse scattering, but its detection can be facilitated at reduced temperatures.

Summary The electronic properties of finite-sized graphene fragments are strongly dependent on their topological structures. The existence of two or more extended zigzag edges could lead to unique open-shell character and magnetic activity. In this review, various types of well-defined graphene nanoribbons, nanographenes, and graphene-like molecules with open-shell character are summarized. Particularly, chemistry and electronic properties of graphene fragments with one, two, and three pairs of parallel zigzag edges, zethrenes with quinoidal structures, and [n]triangulenes with three zigzag edges are discussed in detail. Synthesis of this kind of open-shell molecules is very challenging, and both solution-phase and on-surface chemistry have been used. Their radical characters can be simply predicted in terms of Clar’s sextets and quantitatively analyzed by spin-unrestricted density functional theory or multireference quantum mechanical calculations. Their unique magnetic activity and quantum properties would render them promising materials for all carbon-based spintronic and quantum devices.

Mesenchymal stem cell (MSC)-based chondrogenesis is modulated by diverse biophysical cues. We have previously shown that brief, low-amplitude pulsed electromagnetic fields (PEMFs) differentially enhance MSC chondrogenesis in scaffold-free pellet cultures versus conventional tissue culture plastic (TCP), indicating an interplay between magnetism and micromechanical environment. Here, we examined the influence of PEMF directionality over the chondrogenic differentiation of MSCs laden onto electrospun fibrous scaffolds of either random (RND) or aligned (ALN) orientations. Interactions were detected between magnetic field orientation with that of the cells that combined with micromechanical environment at the level of mitochondrial respiration. Based on pFAK staining and YAP localisation, MSCs on the RND scaffolds were shown to be experiencing the least amount of resting mechanical stress and were found to undergo robust chondrogenic differentiation in response to PEMF exposure perpendicular to the dominant plane of the scaffolds (Z-directed) for only ten minutes at an amplitude of 1 mT. By contrast, MSCs plated onto TCP or the ALN scaffolds gave indications of greater resting mechanical stress accordingly, were unresponsive, or responded negatively, to Z-directed PEMFs. Such interactions agree with a mitohormetic mechanism of cumulative interaction between magnetic fields and the mechanical environment. Moreover, PEMFs demonstrated a strong interaction with MSC alignment, whereby Y-directed magnetic fields applied parallel to the long-axis of MSCs on Y-ALN scaffolds exhibited reduced chondrogenesis. These results indicate that diverse biophysical parameters interact with magnetic fields to culminate in a final cell response that will need to be taken into consideration when designing an effective magnetic exposure paradigm.

CO2 reduction (CO2RR) and hydrogen evolution reactions (HER) are widely used in advanced energy conversion systems, which are urgently required low-cost and high efficient electrocatalysts to overcome the sluggish reaction kinetic and ultralow selectivity. Here, the single-, double-, and triple-atomic Cu embedded graphdiyne (Cu1-3@GDY) complexes have been systematically modeled by first-principles computations to evaluate the corresponding electric structures and catalytic performance. The results revealed that these Cu1-3@GDY monolayers possess high thermal stability by forming the firm Cu–C bonds. The Cu1-3@GDY complexes exhibit good electrical conductivity, which could promote the charge transfer in the electroreduction process. The electronic and magnetic interactions between key species (∗H, ∗COOH, and ∗OCHO) and Cu1-3@GDY complexes are responsible for the different catalytic performance of HER and CO2RR on different Cu1-3@GDY sheets. The Cu2@GDY complex could efficiently convert CO2 to CH4 with a rather low limiting potential of −0.42 V due to the spin magnetism of catalysts. The Cu1@GDY and Cu3@GDY exhibit excellent HER catalytic performance, and their limiting potentials are −0.18 and −0.02 V, respectively. Our findings not only provide a valuable avenue for the design of atomic metal catalysts toward various catalytic reactions but also highlight an important role of spin magnetism in electrocatalysts.

In the last decades, magnetic ceramics are very appealing materials that find applications in several technologic fields. Among these, iron oxides nanoparticles are the main relevant ones due to their low-cost as naturally occurring substrates. However, depending on the application, it can be necessary to induce a specific shape and size control over the final morphology, and consequently a proper synthetic route becomes mandatory. Hence, this document provides a summary of the main relevant chemical, physical, thermal, and biological methods to induce a certain degree of morphological control in iron oxides. The main focus of this document relies on highlighting the principal guidelines, unveiling both advantages and disadvantages of each method in terms of morphology control in the resulting products. Lastly, a particular emphasis has been dedicated toward the industrial feasibility of all processes here discussed. Resumen: En las últimas décadas, la cerámica magnética es un material muy atractivo que encuentra aplicaciones en varios campos tecnológicos. Entre estos, las nanopartículas de óxidos de hierro son las principales por su bajo costo como sustratos naturales. Pero, dependiendo de la aplicación, puede ser necesario inducir un control de forma y tamaño específico sobre la morfología final y, por lo tanto, una ruta sintética adecuada se vuelve obligatoria. Por esta razón, este documento ofrece un resumen de los principales métodos químicos, físicos, térmicos y biológicos relevantes para inducir un cierto grado de control morfológico en los óxidos de hierro. El objetivo principal de este documento se basa en resaltar las principales directrices, revelando las ventajas y desventajas de cada método en términos de control de la morfología en los productos resultantes. Por último, se ha dedicado un énfasis particular a la viabilidad industrial de todos los procesos aquí discutidos.

Zinc sulphide (ZnS) nanoparticles are well known as one of the important inorganic semiconductors. Bandgap, shape, size and synthesis processes are the important parameters which decide the properties of NPs. Therefore the properties of nanoparticles (NPs) can be modified for a specific application by engineering it bandgap and size. In this paper ZnS and Cu doped ZnS (Cu-ZnS) nanoparticles were synthesized by chemical co-precipitation method. The Effect of thermal treatment on Cu-ZnS nanoparticles have been investigated via various characterization techniques. XRD studies confirm the formation of ZnS and Cu-ZnS NPs. Desulphurization of synthesized Cu-ZnS NPs has been observed at temperature 450 °C and above. From UV–Vis spectra, we observed the absorption wavelength of as synthesized ZnS and Cu-ZnS NPs around 215 nm and 218 nm respectively. Red shift in the bandgap of Cu-ZnS NPs has been observed due to annealing. There is a lack of reports on the effect of annealing temperature on magnetism in transition metal doped ZnS nanoparticles. Therefore Magnetic behaviour of synthesized sample has been studied via Vibrating Sample Magnetometer measurement. We have observed that the Cu-ZnS NPs exhibit ferromagnetism. We have reported the increased saturation magnetization at 450 °C. Maximum coercivity of 270 Oe has been observed for Cu-ZnS samples annealed at 350 °C. Thus this paper highlights the effect of annealing temperature of optical, structural and magnetic properties of Cu doped ZnS nanoparticles.

BiFeO3(BFO) and Bi0.90Ba0.10Fe1-xSnxO3(x = 0, 0.01 and x = 0.03) compounds were synthesized by conventional solid-state route. X-ray diffraction (XRD) patterns demonstrated that the compounds crystalized in rhombohedral structure with R3c (IUCr No. 161) space group. The XRD patterns and Fourier transformation infrared spectra evidenced that the crystal structure was distorted due to the substitutions. The magnetic properties of the compounds were greatly influenced by the substitution of Ba and Sn elements at their respective sites. The appearance of weak ferromagnetism with significant remnant magnetization and improved coercive field compared to that of BFO could be ascribed to suppression of spiral modulated spin structure. Higher breakdown voltages were observed in the substituted compounds from the polarization measurements.

Composite thick films of dielectrics having magnetism are promising for variety of electronics applications. Polyvinylidene fluoride (PVDF) as polymer matrix for composites is very impressive due to its high dielectric values and less loss tangent, also the ferroelectric property in β phase among other phase has also been very tempting in polymer family. Barium Hexaferrite, i.e. BaFe12O19 (BHF) is a ferromagnetic material having large saturation magnetisation and high coercively. Thus, the combination of these two materials having composite film may lead to multiferroic properties which are good for enhancing magneto-dielectric properties with the flexibility of the polymer. PVDF based BaFe12O19 (BHF) was successfully synthesized into a free standing flexible thick film by using sol gel method. The thickness of the films was in the range of 40 μm to 50 μm. Phase purity of the film was investigated by X-ray diffraction and the dielectric properties under the applied magnetic field were studied up to 10 MHz frequency. Extremely high values of dielectric permittivity values beyond 500 were observed for the composite thick films. Very small effects magnetic field was seen. A monotonous increase in the AC conductivities with increasing BHF doping in PVDF were observed. The BHF nanoparticles matrices between the chains of PVDF acts as the external source to polarise the PVDF-α, γ, δ phases into ferroelectric crystalline β-phase under the presence of electric field which helps to improve the dielectric value. Moreover, interfacial spaces between BHF and PVDF heterogeneous mixtures give raise to Maxwell-Wagner-Sillar effect which in turn enhances the dielectric permittivity of the composite thick film.

Manganites have attracted much attention due to the simultaneous existence of ferroelectricity and magnetism in the same phase. In this work, barium doped YMnO3 ceramic (Y0.90Ba0.10MnO3) has been synthesized by physical route solid-state reaction method and its structural and dielectric analyses have been done. The X-ray diffraction patterns of the given ceramic disclose its hexagonal crystal structure having P63cm space group symmetry. The Rietveld refinement of the material was done to obtain the lattice parameters. The variation of dielectric constant and dielectric loss as a function of frequency reveals the usual dispersion behavior. The modulus spectroscopy of the sample displays the transport phenomenon.

We report sol–gel auto-combustion synthesis of Ni1-xCdxFe2O4 (0.0–0.72) nano-ferrites (grain-diameter:13.8–28.6 nm) with no thermal-treatment and, its study by x-ray diffraction (XRD), scanning-electron-microscopy-energy-dispersive-x-ray-spectroscopy (SEM-EDS), vibration sample magnetometery, ultraviolet–visible (Uv–Vis) spectroscopic techniques. XRD, EDS confirm formation of spinel phase, with minor-presence of α-Fe2O3 phase. Results show linear increase of lattice parameter; strong compositional dependence of: cationic-distribution (Fe3+ Ni2+ ions more-populated on B-site, Cd2+ distributed on A, B site); inversion-degree; oxygen-parameter; very-similar mean-particle-agglomerate-size; variation of B-O-B A-O-B A-O-A super-exchange-interaction affect magnetic properties. Magnetism is governed by Yafet-Kittel three-sub-lattice model; studied samples remain in the overlap region between single/ multi-domain structures.

SrRuO3 is an orthogonally distorted perovskite (Pbnm) structure whose ferromagnetism is often viewed as an itinerant ferromagnet. Although SrRuO3 has been studied for more than half a century, its structure, magnetism and transport properties are still poorly understood. In this paper, the structure and magnetic evolution of SrRuO3 are discussed in depth through the substitution of Ca2+ for Sr2+ at A sites. The results show that as the Ca substitution increases, the lattice constant decreases, the orthogonal distortion becomes larger, and the saturation magnetization MS, Curie temperature TC and Weiss temperature θp decrease accordingly. Eventually, the ferromagnetic SrRuO3 changes to paramagnetic CaRuO3. The critical exponent β of samples with different substitution contents was obtained by fitting the experimental results, and the value for SrRuO3 (β = 0.55) was similar to that obtained by mean field theory. However, the value increases with the substitution x of Ca, which can't be explained by any scaling theory. The results show that the increase in the value of β is related to the magnetic disorder caused by different magnetic interactions. Analysis using the Rhodes-Wohlfarth criterion indicates that Sr1-xCaxRuO3 has both itinerant-electron and localized-electron magnetism, which is consistent with the theoretical predictions.

Oxide heterointerface is a platform to create unprecedented two-dimensional electron gas, superconductivity and ferromagnetism, arising from a polar discontinuity at the interface. In particular, the ability to tune these intriguing effects paves a way to elucidate their fundamental physics and to develop novel electronic/magnetic devices. In this work, we report for the first time that a ferroelectric polarization screening at SrTiO3/PbTiO3 interface is able to drive an electronic construction of Ti atom, giving rise to room-temperature ferromagnetism. Surprisingly, such ferromagnetism can be switched to antiferromagnetism by applying a magnetic field, which is reversible. A coupling of itinerant electrons with local moments at interfacial Ti 3d orbital was proposed to explain the magnetism. The localization of the itinerant electrons under a magnetic field is responsible for the suppression of magnetism. These findings provide new insights into interfacial magnetism and their control by magnetic field relevant interfacial electrons promising for device applications.

Polycrystalline CuFeO2 (CFO) and CuFe0.99R0.01O2 (R–CFO, R = La, Sm, Eu, Gd, Dy, and Ho) were prepared via solid-phase synthesis to investigate the effects of rare-earth (R) ion addition on the microstructures and magnetism. Positron annihilation lifetime spectroscopy (PALS) experimental results demonstrated that the size, concentration, and defect types were altered by R substitution due to the competition between the agglomeration of small-sized defects and the decomposition of vacancy clusters, which resulted in the redistribution of electrons around annihilation sites. The magnetic measurements revealed that the antiferromagnetic stability was influenced by R substitution, which was ascribed to the effect of magnetic moments, variations in exchange interactions, and the partial reduction of spin frustration. The magnetization behaviors of the R–CFO samples were also influenced by doping ions, which was mainly explained by the different magnitudes of the R ions’ magnetic moments. Ferromagnetism and antiferromagnetism were present in all of the samples. The local electron density ne was associated with the maximum magnetization (Mm). The correlative physical mechanisms are discussed in detail. The results demonstrated that the ne plays an important role in regulating the magnetic properties of CFO ceramics.

Room-temperature ferromagnetic materials are required for new flourishing spintronic technology. Synthesis of co-doped (Gd, Sn) BiFeO3 (Bi1-xGdxFe1-ySnyO3, x = 0, 0.1, 0.15, 0.25; y = 0.1) nanoparticles and nanohybrid co-doped BiFeO3/MXene system as well as structural morphological, electronic and ferromagnetic properties are analysed. XRD patterns showed distorted rhombohedral structure of pure BFO which undergoes transition of phase from rhombohedral to orthorhombic structure due to the Gd substitution in BFO. From SEM, clear voids and porous network can be observed and agglomeration of particles can be due to the addition of Gd substitutions to the BFO. The hysteresis behaviour was revealed for different concentrations of magnetically active Gd added in BFO host, increments in the concentration of Gd resulted in enhanced saturation magnetizations for different samples mainly due to the alteration in antiferromagnetic ordering at the particle's surface, phase transition due to the Gd substitution, collapse of space modulated spin, suppression of oxygen vacancies and increase in number of Fe ions. The magnetization of the hybrid system shows a clear hysteresis behaviour but with decreased saturation magnetization which is attributed to the super exchange effect at the BGFSO and Ti3C2 interface. Unlike the other reports on magnetism in 2D materials, the present work presents magnetic effect in MXene hybrid system which opens up new material designs for 2D spintronics.

Antiferromagnetism (AF) in AB'-stacked centrosymmetric bilayer (BL) CrI$_3$ breaks both spatial inversion ($P$) and time-reversal ($T$) symmetries but maintains the combined $PT$ symmetry, thus inducing novel second-order nonlinear optical (NLO) responses such as second-harmonic generation (SHG), linear electric-optic effect (LEO) and bulk photovoltaic effect (BPVE). In this work, we calculate AF-induced NLO responses of the BL CrI$_3$ based on the density functional theory with the generalized gradient approximation (GGA) plus onsite Coulomb correlation (U), i.e., the GGA+U method. Interestingly, we find that the magnetic SHG, LEO and photocurrent in the AF BL CrI$_3$ are huge, being comparable or even larger than that of the well-known nonmagnetic noncentrosymmetric semiconductors. For example, the calculated SHG coefficients are in the same order of magnitude as that of MoS$_2$ monolayer (ML), the most promising 2D material for NLO devices. The calculated LEO coefficients are almost three times larger than that of MoS$_2$ ML. The calculated NLO photocurrent in the CrI$_3$ BL is among the largest values predicted so far for the BPVE materials. On the other hand, unlike nonmagnetic semiconductors, the NLO responses in the AF BL CrI$_3$ are nonreciprocal and also switchable by rotating magnetization direction. Therefore, our interesting findings indicate that the AF BL CrI$_3$ will not only provide a valuable platform for exploring new physics of low-dimensional magnetism but also have promising applications in magnetic NLO and LEO devices such as frequency conversion, electro-optical switches, and light signal modulators as well as high energy conversion efficiency photovoltaic solar cells., Comment: 10 pages, 7 figures

Though the significance of magnetism in material properties has been well recognized, there are many difficulties and limitations in the identification techniques of magnetism. Noting the magnetic order of FeSe monolayer is important for understanding its superconductivity and remains mysterious, we take it as an example to demonstrate that electric measurements may be applied to identify the magnetic order, by utilizing the magnetic-electric correlation. The contrasts in scanning tunneling microscopy topography, superconducting gaps near defects and evolution of the electronic band structures under in-plane strain for different magnetic orders, are presented as strong evidence, or fingerprints, for the existence of checkerboard antiferromagnetic order in the FeSe monolayer observed in these experiments, and the Fe–Se–Fe exchange interaction is identified to be responsible for the correlation between Fe–Se (electric) bonding states and magnetic orders.

This paper explains the construction of a novel augmented hunger games search algorithm using a logarithmic spiral opposition-based learning technique. The proposed algorithm (LsOBL-HGS) is used as an efficient tool for both function optimization and controller design. To assess the performance of the algorithm for function optimization, benchmark functions from the CEC2017 test suite were employed and comparisons were made with available and good performing algorithms. In terms of controller design, the proposed LsOBL-HGS algorithm was utilized to design a FOPID controlled magnetic ball suspension system. Comparative assessments were also performed for FOPID controller design, as well using other state-of-the-art methods reported for the magnetic ball suspension system. The results showed that the proposed LsOBL-HGS algorithm has good capability for FOPID controller design employed in a magnetic ball suspension system as it provided an improvement of more than 13% in terms of the transient response-related parameters and more than 34% in terms of bandwidth compared to the best-reported approach used for comparisons. © 2022 Karabuk University