Large Magnetic Moment Research Articles

Ball-milling fabrication of n-p heterojunctions Bi4O5Br2/α-MnS with strengthened photocatalytic removal of bisphenol A in a Z-Scheme model

In this investigation, α-MnS with a large magnetic moment was typically selected to modify Bi4O5Br2 to produce a train of binary n-p heterojunction composites Bi4O5Br2/α-MnS (BMS) through a facile mechanical ball-milling manner. These achieved composites were subsequently subjected to physicochemical properties analyses. It was confirmed that both expected components were present and integrated into heterojunction structures. An endocrine disruptor bisphenol A (BPA) was typically selected as a target contaminant to estimate photocatalytic degradation efficiency under visible light. Under the identical condition, composites BMS exhibited obviously improved degradation efficiencies. Notably, the best catalog, composite BMS0.05, displayed the best catalytic outcome with an apparent reaction rate constant of 2.67 times that of Bi4O5Br2, primarily ascribed to the strengthened visible-light absorption, suitable phase composition, and boosted generation of reactive radicals caused by efficient carries redistribution and segregation along the appropriate band alignment. In addition, some reaction parameters were varied to optimize such a photocatalytic system. Moreover, degradation pathways were speculated through intermediates detection. Eventually, a rational Z-scheme photocatalysis mechanism was proposed in the light of capture experiments and band structure estimation.

First-principles study of polar magnets corundum double-oxides Mn2FeMO6 (M = W and Mo)

The physical properties of the corundum double-oxides Mn2FeMO6 (M = W and Mo) are investigated using density functional theory (DFT). The structure relaxation in different spin orders are performed and ferrimagnetic is found the most stable magnetic phase. The compounds are dielectric materials with band gap values 1.84 and 2.03 eV. These materials are polar magnets because of the coexistence of contradictory properties such as polarization and magnetization, which are observed very rarely. The electric polarization arises due structure distortion and cation orbital configuration of M atom, while the magnetization occurs due to unpaired dn of Mn and Fe orbital configuration. The compounds understudy are suitable for ferroelectric and magneto-electric applications due to their large spontaneous polarization (58.16 and 69.24 µC/cm2) and magnetic moments (3 and 3.43 µB/f.u). These multiferroic Mn2FeMO6 exhibit a profound interplay between electrical polarization and the applied magnetic field. The calculated values of piezoelectric coefficient, d33 = 264 and 606 pC/N are comparable to lead-based piezoelectric materials. A set of mechanical parameters revealed that Mn2FeMO6 are mechanically stable in rhombohedral phase. The applied strain has great influence on the physical properties of these two compounds.

Antiferromagnetic Spin Orientation and Magnetic Domain Structure in Epitaxially Grown MnN Studied Using Optical Second-Harmonic Generation

$\mathrm{Mn}\mathrm{N}$ is a centrosymmetric collinear antiferromagnet belonging to the transition-metal-nitride family with a high N\'eel temperature ($660\phantom{\rule{0.2em}{0ex}}\mathrm{K}$), a low anisotropy field, and a large magnetic moment ($3.3{\ensuremath{\mu}}_{B}$ per $\mathrm{Mn}$ atom). Despite several recent experimental and theoretical studies, the spin symmetry (magnetic point group) and magnetic domain structure of the material remain unknown. In this work, we use optical second-harmonic generation (SHG) to study the magnetic structure of thin epitaxially grown single-crystal (001) $\mathrm{Mn}\mathrm{N}$ films. Our work shows that spin moments in $\mathrm{Mn}\mathrm{N}$ are tilted away from the [001] direction and the components of the spin moments in the (001) plane are aligned along one of the two possible in-plane symmetry axes ([100] or [110]), resulting in a magnetic-point-group symmetry of 2/m1'. Our work rules out magnetic-point-group symmetries 4/mmm1' and mmm1' that have been previously discussed in the literature. Four different spin domains consistent with the 2/m1' magnetic-point-group symmetry are possible in $\mathrm{Mn}\mathrm{N}$. A statistical model based on the observed variations in the polarization-dependent intensity of the second-harmonic signal collected over large sample areas puts an upper bound of $0.65\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}$ on the mean domain size. Our results show that SHG can be used to probe the magnetic order in metallic antiferromagnets. This work is expected to contribute to the recent efforts in using antiferromagnets for spintronic applications.

Three-Dimensional Magnetohydrodynamic Analysis of a Magnetic Sail Using a Deployable Modular Structure

To obtain significant drag from a magnetic sail, it is necessary to generate a large magnetic moment. However, even with superconducting coils, a coil radius of several kilometers is required to obtain a significant drag force due to the magnetic moment generated by the coil alone. Therefore, several methods have been proposed to expand the magnetosphere generated by the coil, such as mini-magnetospheric plasma propulsion devices. This paper proposes a method to expand the magnetosphere and increase the drag by arranging multiple coils printed on a thin membrane in a deployable modular structure. To investigate the increased drag achieved by using this arrangement, a three-dimensional magnetohydrodynamic analysis is performed, and the drag coefficient and the shape of the magnetosphere are compared for several different coil arrangements and distances between coils. It is found that the drag force depends on the coil arrangement and that the effect is related to changes in the structure of the magnetosphere.

Single-Ion Behavior in New 2-D and 3-D Gadolinium 4f7 Materials: CsGd(SO4)2 and Cs[Gd(H2O)3(SO4)2]·H2O.

The recent creation of 4f7 gadolinium materials has enabled vital studies of the free-ion properties of the Gd(III) cations. While the 8 S ground state in a trivalent Gd compound is, in principle, isotropic, it has been demonstrated that there is a residual orbital angular momentum affected by the crystal field and structural distortion in certain systems. By exploiting the atomistic control innate to material growth, we address a fundamental question of how the isotropic nature of Gd(III) is preserved in different dimensionalities of crystal structures. To achieve this, we designed two new trivalent Gd materials possessing two structurally distinct features, a 2-D CsGd(SO4)2 and a 3-D Cs[Gd(H2O)3(SO4)2]·H2O. The tunability of the structural dimension is facilitated by O-H---O hydrogen bonds. The structural divergence between the two compounds allows us to investigate each material individually and make a comparison between them regarding their physical properties as a function of lattice dimension. Our results demonstrate that structural dimensions have a negligible effect on the single-ion behavior of the materials. Magnetization measurements for the Gd(III) complexes yielded paramagnetic states with the isotropic spin-only nature. Specific heat data suggest that there is a lack of magnetic phase transition down to T = 1.8 K, and coupled lattice vibrations in the materials are attributable to strong covalent bonding characters of the (SO4)2- and H2O ligands. This work offers a pathway for retaining the single-ion property of Gd(III) while constructing the large spin magnetic moment S = 7/2 in large-scale extended frameworks.

Effect of substitution of Mn and Ga atoms by Fe atom in the Mn2GaC MAX phase

The magnetic properties of ordered and disordered MAX-phase Mn2-xFe2xGaC and Mn2Ga1-xFexC (x = 12.5, 25, and 50 at.%) have been studied within DFT-GGA. The investigation of phase stability of M2AX phases is performed by comparing the total energy of MAX phases to that of the set of competitive phases for calculation of the phase formation enthalpy. At the small concentration of Fe atoms (x = 12.5 %) compound remains stable. We have found that introducing Fe atom at A-site leads to the forming of ferromagnetic phase with large magnetic moments on magnetic atoms and magnetization. Through detailed group-theoretical analysis we have obtained that only ferromagnetic ordering is possible when Fe atom ordering over Ga sites. The study of exchange constants shows that the out-of-plane Fe-Mn exchange gives the main contribution in appearance of ferromagnetic phase. The temperature dependences of magnetization reveal the increase of Curie temperature in Mn2GaC with Fe atom incorporated into Ga-site.

On-Surface Design of a 2D Cobalt-Organic Network Preserving Large Orbital Magnetic Moment.

The design of antiferromagnetic nanomaterials preserving large orbital magnetic moments is important to protect their functionalities against magnetic perturbations. Here, we exploit an archetype H6HOTP species for conductive metal-organic frameworks to design a Co-HOTP one-atom-thick metal-organic architecture on a Au(111) surface. Our multidisciplinary scanning probe microscopy, X-ray absorption spectroscopy, X-ray linear dichroism, and X-ray magnetic circular dichroism study, combined with density functional theory simulations, reveals the formation of a unique network design based on threefold Co+2 coordination with deprotonated ligands, which displays a large orbital magnetic moment with an orbital to effective spin moment ratio of 0.8, an in-plane easy axis of magnetization, and large magnetic anisotropy. Our simulations suggest an antiferromagnetic ground state, which is compatible with the experimental findings. Such a Co-HOTP metal-organic network exemplifies how on-surface chemistry can enable the design of field-robust antiferromagnetic materials.

Activation of h‐BN and SiC monolayer sheets through foreign atom substitution; a comparative study based on ab‐initio method

AbstractHere, we studied two different 2D monolayer systems (i.e., h‐BN and SiC), which exhibit unique electronic and magnetic properties. We analyzed the effects of Transition Methods (TM) doped atoms (i.e., Mn, Ni, and Sc) on the single vacancy (SV) h‐BN and SiC systems using first principles calculations. Through comparison we found that Mn substitution in SV h‐BN and SiC can modify their electronic and magnetic properties having larger magnetic moment as compared to other dopants (i.e., Ni and Sc.). Band structure and PDOS plots confirmed that TM doping in SV h‐BN can convert the pure h‐BN (insulator) to semiconductor, metal, or semi‐metal, it is also observed from the results that Mn‐doped h‐BN has higher band gap approximately equal to Eg ~ 2.7 eV during the negative spin and has smaller band gap, that is, (Eg ~ 1.1 eV) during the positive spin. Similarly doping with the TM atoms on the SV SiC monolayer system can convert pure SiC to metal or half metal. In addition, Mn‐doped SiC showed semimetal property having 0 eV band gap. These finding will help us to vary the electronic and magnetic properties of the pure h‐BN and SiC sheets which can be used for the opto‐electronic and spintronic applications.

Sm cluster on hexagonal boron nitride supported by Ir(111): Formation of magnetic cluster superlattice Sm13[formula omitted]h-BN[formula omitted]Ir(111)

The goal toward the ultimate density limit of magnetic information storage is now focused on the creations of identical magnetic clusters as well as their arrangements on a template surface for obtaining an equidistant, monodisperse and equally oriented pattern. To achieve this goal, the combination of rare-earth (RE) cluster and specific template is a viable route, e.g., h-BN monolayer on Ir(111) surface within a corrugated moiré structure (h-BN|Ir(111)) can act as a promising template to steer the intrinsically magnetic RE cluster in a well-defined orientation. Combining abinito molecular dynamic (AIMD) simulation and spin–orbital coupling density function theory (DFT) calculations, we report that magnetic Sm13 cluster can be stably deposited at the pore region of h-BN|Ir(111) template. The low-lying moiré region potential of h-BN|Ir(111) template, stable icosahedron structure of Sm13 cluster, and strong hybridization of Sm-5d6s orbitals with B/N-sp orbitals, play the synergetically roles to form Sm13@h-BN|Ir(111) cluster superlattice. The local magnetic moments of Sm atoms in Sm13 cluster are found to be robust against the structural configuration, localized site and inter-atom magnetic coupling, because their highly localized 4f states hybridize less with the spd states. Nevertheless, different deposition orientations and consequently the altered bonding interactions between Sm atoms and h-BN monolayer lead to different magnetic orders among Sm atoms. The appearances of large magnetic moment and giant magnetic anisotropy energy (MAE) of Sm13 cluster as well as its high deposition stability render Sm13@h-BN|Ir(111) for potential application of magnetic storage.

Electronic and magnetic properties of iridium-based novel Heusler alloys

Half-metallicity and magnetism including exchange splitting are the most significant physical parameters to predict and design a candidate material for spintronic applications. We report here an ab-initio investigation on chemical formation and dynamical stability along with electronic structure and magnetic properties of Ir2Cr (Si, Ge) and IrRhCr (Si, Ge) Heusler alloys. The negative formation and cohesive energies with positive phonon dispersions confirm the stabilities of these alloys. Electronic structure calculations reveal that Ir2Cr (Si, Ge) and IrRhCrSi alloys are half-metallic ferromagnets with unprecedented exchange splitting. In addition, IrRhCrGe also shows semi-metallic nature. All of these materials follow Slater Pauling rule with large magnetic moments and 100% spin-polarization. With Cr bearing the majority of the local magnetic moment and exchange splitting, a ferromagnetic state is more stable than a nonmagnetic state. The electronic charge distribution and population analysis confirm mixed ionic and covalent bonding. The magnetocrystalline anisotropy energy, with the easy magnetization along the [1 1 1] direction, is significantly high in Ir2CrGe. Elastic constants such as shear (G), bulk (B), Young’s moduli, and Poisson’s ratio indicate that the IrRhCrSi and IrRhCrGe alloys are mechanically stable, and Ir2CrSi and Ir2CrGe are mechanically unstable. The Pugh’s (B/G) and Poisson’s ratios confirm that the stable alloys are ductile.

Suppression of zero-field quantum tunneling of magnetization by a fluorido bridge for a "very hard" 3d-4f single-molecule magnet

<h2>Summary</h2> Single-molecule magnets (SMMs) have been proposed for ultra-high-density information storage due to prolonged relaxation times below blocking temperature (<i>T</i>_B). However, many SMMs suffer from fast magnetization loss at zero-field regime due to the quantum tunneling of magnetization (QTM) effect. Here we show the creation of large ground magnetic momentum is crucial to suppress zero-field QTM for SMMs. The recipe is to use bridging fluoride, which creates ferromagnetic couplings among the lanthanide ions in the complex [Dy₃Cr₃(<i>μ</i>₃-F) (<i>μ</i>₃-OH)₃(mdea)₃(piv)₈DMF]·H₂O·CH₃CN. As such, the molecule owns a large ground magnetic moment of <mml:math><mml:mrow><mml:mn>10.7</mml:mn><mml:mi>μ</mml:mi><mml:mi>B</mml:mi></mml:mrow></mml:math> and is confirmed to be an SMM with <i>T</i>_B of 5 K. More importantly, a "very hard" magnetic hysteresis loop with a coercive field of 1.3 T and more than 97% remanence is observed up to 0.7 K. <i>Ab initio</i> calculations fully support such observations, rendering the importance of fluorido bridge to suppress zero-field QTM for lanthanide-based SMMs.

Simultaneous Detection of Circularly Polarized Luminescence and Raman Optical Activity in an Organic Molecular Lemniscate.

Circularly polarized luminescence (CPL) and Raman optical activity (ROA) were observed in a single spectroscopic experiment for a purely organic molecule, an event that had so far been limited to lanthanide‐based complexes. The present observation was achieved for [16]cycloparaphenylene lemniscate, a double macrocycle constrained by a rigid 9,9′‐bicarbazole subunit, which introduces a chirality source and allows the molecule to be resolved into two configurationally stable enantiomers. Distortion of oligophenylene loops in this lemniscular structure produces a large magnetic transition dipole moment while maintaining the π‐conjugation‐induced enhancement of the Raman signal, causing the appearance of the CPL/ROA couple. A two‐photon mechanism is proposed to explain the population of the lowest‐energy excited electronic state prior to the simultaneous emission‐scattering event.

Simultaneous Detection of Circularly Polarized Luminescence and Raman Optical Activity in an Organic Molecular Lemniscate

AbstractCircularly polarized luminescence (CPL) and Raman optical activity (ROA) were observed in a single spectroscopic experiment for a purely organic molecule, an event that had so far been limited to lanthanide‐based complexes. The present observation was achieved for [16]cycloparaphenylene lemniscate, a double macrocycle constrained by a rigid 9,9′‐bicarbazole subunit, which introduces a chirality source and allows the molecule to be resolved into two configurationally stable enantiomers. Distortion of oligophenylene loops in this lemniscular structure produces a large magnetic transition dipole moment while maintaining the π‐conjugation‐induced enhancement of the Raman signal, causing the appearance of the CPL/ROA couple. A two‐photon mechanism is proposed to explain the population of the lowest‐energy excited electronic state prior to the simultaneous emission‐scattering event.

Probing the structural evolution and its impact on magnetic properties of FeCoNi(AlMn)x high-entropy alloy at the nanoscale

We report the first nanoscale investigation of FeCoNi(AlMn) x high-entropy alloys (HEAs) processed by laser metal deposition. The structural evolution of the alloy upon chemical composition variation (0.2 ≤ x ≤ 1.5) was investigated by combining imaging and spectroscopies in (scanning) transmission electron microscopy (S)TEM with density functional theory (DFT). A gradual change from a face-centered cubic (FCC) towards an ordered full-Heusler (L2 1 ) phase by increasing the Al and Mn contents was observed. Direct imaging and atomic-scale calculations revealed a nanoscale interplay between B2 and L2 1 ordered structures for x = 1.5, wherein the latter, Al and Mn occupy two different Wyckoff sites. By decreasing x, the FCC phase dominates exhibiting intense phase separation tendency, ordering phenomena, and nano-precipitation. Although not chemically discriminated, plasmon-peak splitting in low-loss electron energy loss spectra revealed the presence of two valence electron densities within the FCC phase. Lorentz TEM showed that the ordered nano-precipitates and nano-sized grains with a structure based on a tripled FCC unit cell are pinning-sites for magnetic domain walls and dislocations. All alloy compositions exhibited soft-magnetic behavior with coercivity ( H c ) values< 1000 A/m. The FeCoNi(AlMn) 1.5 alloy with L2 1 /B2 nanostructure showed the highest magnetization ( M s ) with relatively low H c , attributed to the large magnetic moment of Mn and the synergistic effect of Mn-Al according to DFT, whilst ordering does not impose a negative effect. Phase separation trends within the FCC phase seem to decrease the M s however, the overall impact on the magnetic behavior is not intense, opening up for new avenues for tuning FeCoNiAlMn properties through chemically-designed phase decomposition regimes. • First nanoscale investigation of FeCoNi(AlMn)x HEAs processed by LMD, combining advanced (S)TEM and DFT calculations. • Ordering phenomena - nanoscale interplay between B2 and L21, ordered superstructures - and impact on magnetic properties. • Atomic site occupancy resolved by direct imaging and atomic-scale calculations. • Phase separation in FCC opens up avenues for tuning alloy properties through chemically-designed decomposition regimes. • All alloy compositions exhibited soft-magnetic behavior with coercivity values< 1000 A/m.

Bipolar ferromagnetic semiconductor with large magnetic moment: EuGe2 monolayer

Two-dimensional (2D) ferromagnetic semiconductors having both ferromagnetism and semi-conductivity hold exciting and promising potentials in spintronic devices at nanoscale. In this work, we explored the electronic and magnetic properties of EuGe2 monolayer via conducting the first-principles calculations. The electronic band structure shows that EuGe2 monolayer is a bipolar magnetic semiconductor with a band gap of 0.55 eV based on the Heyd-Scuseria-Ernzerhof (HSE06) method. The magnetic moment and Curie temperature of EuGe2 monolayer are calculated to be 7 μBf.u.−1 and 23 K based on the Heisenberg model. Its perpendicular magnetic anisotropy (PMA) energy is 3.62 meV per formula unit. Additionally, the Curie temperature of EuGe2 monolayer is increased by 400% under −8% biaxial compressive stain. Our calculation results suggest that EuGe2 monolayer has potential applications in the field of spintronic devices.

J c and Composition Distribution of YBCO Coated Conductors Fabricated by the TFA-MOD Process

The Trifluoroacetate-Metal Organic Deposition (TFA-MOD) process is one of the most promising fabrication processes for low-cost superconducting coated conductors (CCs) because of its high yield and non-vacuum system. However, in the doping and multi-coating process for the enhancement of critical current (<i>I</i>_c), degradation of <i>I</i>_c often occurs. In this study, to clarify the origin of <i>I</i>_c degradation, we have investigated the local critical current density (<i>J</i>_c) distribution, in-field <i>J</i>_c properties and the variation of composition for TFA-MOD processed YBa₂Cu₃O_y (YBCO) CCs. The local <i>J</i>_c distributions were measured by Scanning Hall-Probe Microscopy for confirming the location of the high&#x002F;low-<i>J</i>_c regions. The CCs were then cut into 3 mm&#x00D7;3 mm or 3 mm&#x00D7;4 mm for dc magnetization measurement. The <i>T</i>_c of the all samples were about 87 K to 90 K. In-field <i>J</i>_c at 77 K was obtained from <i>M</i>-<i>H</i> measurements and all the samples were compared with each other. The in-field <i>J</i>_c of high-<i>J</i>_c sample showed about 100 times higher value than that of the low-<i>J</i>_c sample. Then we have observed the microchemistry and the variation of composition by SEM-EDS. In the high-<i>J</i>_c sample, the grains of the superconducting phase were large in size and were connected to each other. This means that superconducting current could form through the whole sample area and generate a large magnetic moment. On the other hand, in the low-<i>J</i>_c sample, though the superconducting phase could be observed, the grains were small in size and sparse. Therefore, the magnetic moment measured was small. However, it was also suggested that the intra-grain <i>J</i>_c would be almost the same as that of high-<i>J</i>_c sample.

Multifunctional two-dimensional van der Waals Janus magnet Cr-based dichalcogenide halides

Two-dimensional van der Waals Janus materials and their heterostructures offer fertile platforms for designing fascinating functionalities. Here, by means of systematic first-principles studies on van der Waals Janus monolayer Cr-based dichalcogenide halides CrYX (Y = S, Se, Te; X = Cl, Br, I), we find that CrSX (X = Cl, Br, I) are the very desirable high TC ferromagnetic semiconductors with an out-of-plane magnetization. Excitingly, by the benefit of the large magnetic moments on ligand S2− anions, the sought-after large-gap quantum anomalous Hall effect and sizable valley splitting can be achieved through the magnetic proximity effect in van der Waals heterostructures CrSBr/Bi2Se3/CrSBr and MoTe2/CrSBr, respectively. Additionally, we show that large Dzyaloshinskii–Moriya interactions give rise to skyrmion states in CrTeX (X = Cl, Br, I) under external magnetic fields. Our work reveals that two-dimensional Janus magnet Cr-based dichalcogenide halides have appealing multifunctionalities in the applications of topological electronic and valleytronic devices.

Revealing superstructure ordering in Co1+xMnSb Heusler alloys and its effect on structural, magnetic, and electronic properties

We have performed a combined experimental and theoretical study of the ${\mathrm{Co}}_{1+x}\mathrm{MnSb}$ system to understand the progressive evolution of the crystal structure and physical properties as a function of Co content. We find that all the arc-melted polycrystalline samples show superstructure ordering similar to CoMnSb. In the CoMnSb superstructure with $Fm\text{\ensuremath{-}}3m$ symmetry, one set of the $32f$ sites is filled with Co atoms while the other set is vacant. With increasing Co content, although the vacant set of $32f$ sites gets progressively filled with the Co atoms, some of the Co atoms segregate out of the main phase into the grain boundaries. The maximum Co that enters in the ${\mathrm{Co}}_{1+x}\mathrm{MnSb}$ phase is $x=\ensuremath{\sim}0.45$. Thus, we find that the theoretically predicted ${\mathrm{Co}}_{2}\mathrm{MnSb}$ in $L{2}_{1}$ phase does not stabilize. All the samples are ferromagnetic above room temperature and the trend in the measured magnetic moments with increasing $x$, agrees reasonably well with the density-functional theory calculations done using the structural and compositional parameters obtained from the Rietveld refinement of the synchrotron x-ray diffraction patterns. However, the electronic structure indicates that in spite of the large magnetic moment, none of the alloys are half metallic. Finally, we find that a minor deviation from stoichiometry in CoMnSb, i.e., excess of Co and Sb as compared to Mn, is accommodated in the set of vacant $32f$ sites of the superstructure. This explains the increase in the lattice parameter and the saturation magnetization, as compared to the calculated stoichiometric CoMnSb superstructure. Calculations also predict that this minor deviation from stoichiometry destroys the half metallicity in the CoMnSb superstructure.

Light-weight FeCo/CNTs/HNTs triple-phase magnetic composites for high-performance microwave absorption

The preparation of lightweight, as well as high-performance microwave absorption materials, has attracted much attention in recent years, but people are still suffering from the high cost and low yielding of the products. Here a HNTs@CNTs (HCS) microsphere was prepared by spray drying, and then surface assembly of CoFe2O4 via the hydrothermal method to form HCS/CoFe2O4 composite, followed by thermal reduction into HCS/FeCo under H2/Ar atmosphere. The HCS/FeCo show significant performance in both permittivity and permeability due to the combination of the large magnetic moment of the FeCo alloy and the high conductivity of carbon nanotubes, leading to a remarkable enhancement in microwave absorption properties. Thanks to the unique morphology and the synergistic effect of multiple loss mechanisms, the maximum reflection loss of HCS /FeCo reached − 57.77 dB at 12.10 GHz with a matching thickness of only 1.63 mm, and the absorption bandwidth with reflection loss exceeding − 10 dB reached 6.24 GHz (11.76–18.00 GHz), which can completely cover the Ku band. In this strategy, the lightweight halloysite nanotubes are used to match the impedance parameters of the composite, and the spray drying method will facilitate the industrialization of the material.

Prediction of novel two-dimensional room-temperature ferromagnetic rare-earth material - GdB2N2 with large perpendicular magnetic anisotropy

Two-dimensional (2D) ferromagnets with large magnetic anisotropy are promising in modern spintronics, but low Curie temperature and small magnetic anisotropy energy (MAE) hinder their applications seriously. Herein, by employing density functional theory (DFT) calculations, we predict a new kind of 2D ferromagnetic materials - GdB2N2, which possesses large magnetic moment (∼7.87 μB/f. u.), very high Curie temperature (∼335 K) and large perpendicular magnetic anisotropy (∼10.38 meV/f. u.). Biaxial strain ranging from −0.5% to 5% and different concentrations of charge-carrier doping (≤0.5 e/h per f. u.) are further applied to reveal the influence on the Curie temperature and MAE. The magnetic ordering of GdB2N2 is found dominated by a Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism. The prediction of such a novel 2D ferromagnet presented here, not only enriches the family of 2D ferromagnetic materials, but also makes it possible to combine traditional 2D materials and rare-earth metals for achieving more intriguing magnetic properties, which could eventually carve out a new path for the next-generation spintronic devices and sensors.