3d Transition Metal Atoms Research Articles

Bottom-up constructing of two-dimensional ferromagnets with high Curie temperature by assembling 5d transition metal atom@MnSr8 magnetic superatoms

Abstract The development of advanced spintronic devices requires ultrathin two-dimensional (2D) ferromagnetic (FM) materials with high Curie temperature (T C) and large out-of plane magnetic anisotropy energy (MAE). However, the number of high-T C 2D ferromagnets synthesized through top-down experimental methods is very limited. Here, we propose a bottom-up approach for constructing 2D ferromagnets with high T C by assembling magnetic superatoms. The MnSr9 superatom was first selected as building blocks to construct a series of 2D materials with square, triangular and hexagonal honeycomb lattices. First-principles studies show that all the MnSr9 self-assembled films are thermodynamically stable and exhibit ferromagnetism, unfortunately, they lack the necessary magnetic anisotropy. By substituting one Sr atom with a heavy 5d transition metal (5d-TM) atom, all these 5d-TM@MnSr8 clusters show enhanced stability and symmetry, and their self-assembled hexagonal honeycomb crystals exhibit significant magnetic anisotropy and enhanced ferromagnetism from 5d-TM atoms. Taking the PtMnSr8 superatom as an example, we have demonstrated these characteristics in detail, and the T C and out-of-plane MAE of its honeycomb structure reach up to 253 K and 3.47 meV per unit cell under biaxial tensile strain. Moreover, the PtMnSr8 honeycomb structure on hexagonal boron nitride monolayer substrate exhibit further enhanced ferromagnetism (T C ≈ 327 K) and distinctive antioxidant properties. This study highlights that assembling magnetic superatoms on suitable substrates is an effective way for constructing high-performance 2D FM materials.

3d oxide molecules to tailor large magnetic anisotropy energies on MgO films

Designing systems with large magnetic anisotropy energy (MAE) is desirable and critical for nanoscale magnetic devices. A recent breakthrough achieved the theoretical limit of the MAE for 3d transition metal atoms by placing a single Co atom on a MgO(100) surface, a result not replicated by standard first-principles simulations. Our paper, incorporating Hubbard-U correction and spin-orbit coupling, successfully reproduces and explains the high MAE of a Co adatom on a MgO (001) surface. We go further by exploring ways to enhance MAE in 3d transition metal adatoms through different structural geometries of 3d−O molecules on MgO. One promising structure, with molecules perpendicular to the surface, enhances MAE while reducing substrate interaction, minimizing spin fluctuations, and boosting magnetic stability. Additionally, we demonstrate significant control over MAE by precisely placing 3d−O molecules on the substrate at the atomic level. Published by the American Physical Society 2024

Influence of Dopant Atoms in TiO2 for Its Electron Structure and Activity of Oxygen Reduction Reaction in Acidic Environmental

Polymer electrolyte fuel cells (PEFCs) are attracting attention, but their widespread commercialization has various challenges. In particle, the Pt-based cathode catalyst has two significant problems: durability and cost. These problems will persist as long as the Pt-based catalyst is used in PEFCs. Therefore, we focused on TiO2 as the alternative Pt-based catalyst, which is highly durable and low-cost. However, TiO2 has low electron conductivity and must obtain the electron conduction path to progress the oxygen reduction reaction (ORR). In general, doping transition metal and/or introducing the oxygen vacancy into the crystal structure is conducted to enhance the electron conductivity of TiO2. It was reported that Nb-doped TiOx having oxygen vacancies showed relatively higher ORR activity. Experimentally, it is known that other metal doping and oxygen vacancies bring in high ORR activity. However, the detailed enhancement mechanism for ORR activity is still unclear.Some research groups were using theoretical calculations to investigate the mechanism of ORR, such as the reaction path and active site on the TiO2 surface [1, 2]. These reports suggest one of the potentials for the ORR mechanism but don’t completely describe the ORR on the TiO2-based catalyst because it is hard to compute the state of a realistic, accurate ORR system. Therefore, we planned the combination of experiment data and theoretical calculations, and the balance of experimental data was heavier.In this study, the 3d transition metal atom was doped to TiO2 and conducted for the reduction treatment for doped TiO2 to introduce oxygen vacancies. Their ORR activities and electron structure were evaluated experimentally. In addition, the electron structures of all samples were computed using DFT calculation and compared with experimental data.5 at% of transition metal-doped TiO2 and TiO2 were synthesized by sol-gel method. The reduction treatment in this study consisted of calcining at 800°C for 10 min under the H2+Ar mixed gas flow conditions. The electrochemical measurements used a three-electrode cell with a working electrode, a carbon plate counter electrode, an Ag/AgCl reference electrode, and 0.1 M HClO4(60°C). The potential in this study was converted from versus Ag/AgCl to versus RHE. The ORR current was obtained by subtracting currents under inert gas flow conditions from currents under O2 flow conditions. The ORR activity was judged by the potential at 5 mA g-1 of ORR current. DFT calculation was performed with Quantum ESPRESSO.All the synthesized samples had the anatase phase structure, but crystallinity was low since they formed nanoparticles or might not react with precursors completely. XPS results suggested that the dopant atom was probably introduced into the TiO2 crystal structure. The ORR activity of TiO2 was improved by doping the 3d transition metal atoms.The density of states (DOS) of modeled our doped TiO2 samples showed a new intermediate band in the forbidden band of TiO2. Now, we expect that the location, amount, density, and other circumstances of this new intermediate band may be related to ORR activity.[1] F. Zhang, et al. Applied Surface Science, 598 (2022) 153873.[2] Y. Yamamoto, et al. J.phys.Chem.C, 123 (2019) 19486-19492.

Single-Atom catalysts supported by nanographene networks for efficient CO2 electroreduction: A first-principles study

Single-atom materials based on novel 2D nanographene networks and 3d transition metal atoms are constructed. Their structural and thermal stabilities in addition to the catalytic performance toward CO2 reduction are investigated using DFT calculations. Single metal atoms namely, Sc, Ti... Zn are strongly held by the pore C-atoms with high binding energy. Moreover, the dynamical and thermal stabilities are proved by the real vibrational frequencies and the molecular dynamics simulations at 500 K. Comparing the free energy of hydrogen evolution with that of the determinant intermediate in CO2 reduction shows that all the 3d metals, except Cu and Mn, are selective to CO2 reduction. Although the 3d single atom catalysts require a high potential for the overall CO2 conversion to CH3OH or CH4, they show exceptional catalytic performance toward CO2 to CO conversion. The calculated overpotential for CO-production using Sc and Ti is extremely low at 0.13 V making them competitive with the expensive Pt-catalysts. The overall CO2 reduction can be enhanced by considering 4d metals; for instance, an Au-based catalyst significantly reduces the overall energy required for CO2 conversion to CH3OH. Therefore, the constructed single-atom materials with high stability and promising catalytic activity are potential candidates for CO2 electrolysis.

Diatomic Active Sites Embedded Graphyne as Electrocatalysts for Ammonia Synthesis.

Ammonia (NH3) is a vital chemical compound in industry and agriculture, and the electrochemical nitrogen reduction reaction (eNRR) is considered a promising approach for NH3 synthesis. However, the development of eNRR faces the challenge of high overpotential and low Faradaic efficiency. In this work, graphyne (GY) is anchored by 3d, 4d, and 5d dual transition metal atoms to form diatomic catalysts (DACs) and is roundly investigated as an electrocatalyst for eNRR via density functional theory calculations. Due to the protrusion of anchored metal atoms, the active sites of GY are better exposed compared to other substrates, exhibiting higher activity. Through four-step hierarchical high-throughput screening (ΔG*N2 < 0 eV, ΔG*N2→*N2H < 0.4 eV, ΔG*NH2→*NH3 < 0.4 eV, and ΔG*N2 < ΔG*H), the number of selected catalysts in each step is 325, 240, 145, and 20, respectively. Considering a series of factors, including stability, initial potential, and selectivity, 13 kinds of eligible catalysts are identified. Optimal eNRR paths studies show that the best catalyst Mn2@GY features no onset potential. For the three catalysts (Mn2@GY, Ir2@GY, and RhOs@GY), the onset potentials of the most favorable eNRR pathways are -0.07, -0.12, and -0.17 V, respectively. The excellent catalytic activity can be credited to the effective charge transfer and orbital interaction between the active site and adsorbed N2. Our work demonstrates the significance of DACs for ammonia synthesis and provides a paradigm for the study of DACs even for other important reactions.

Design of Single-Atom Catalysts on C5N2 for Nitrogen Fixation at Ambient Conditions: A First-Principles Study.

Single atom catalysts (SACs) exhibit the flexible coordination structure of the active site and high utilization of active atoms, making them promising candidates for nitrogen reduction reaction (NRR) under ambient conditions. By the aid of first-principles calculations based on DFT, we have systematically explored the NRR catalytic behavior of thirteen 4d- and 5d-transition metal atoms anchored on 2D porous graphite carbon nitride C N . With high selectivity and outstanding activity, Zr, Nb, Mo, Ta, W and Re-doped C N are identified as potential nominees for NRR. Particularly, Mo@C N possesses an impressive low limiting potential of -0.39 V (corresponding to a very low temperature and atmospheric pressure), featuring the potential determining step involving *N-N transitions to *N-NH via the distal path. The catalytic performance of TM@C N can be well characterized by the adsorption strength of intermediate *N H. Moreover, there exists a volcanic relationship between the catalytic property U and the structure descriptor , which validates the robustness and universality of , combined with our previous study. This work sheds light on the design of SACs with eminent NRR performance.

Electrochemical CO2 Reduction on Cu-Based Monatomic Alloys: A DFT Study.

In recent years, single-atom alloy catalysts (SAAs) have received much attention due to the combination of structural features of both single-atom and alloy catalysts, as well as their efficient catalytic activity, high selectivity, and high stability in various chemical reactions. In this work, we designed a series of Cu-based SAAs by doping isolated 3d transition metal (TM1) atoms on the surface of Cu(111) (TM1 = Fe, Co, Ru, Rh, Os and Ir), in which Ir1/Cu(111) SAAs are considered to be the most stable among 3d-series SAAs due to their optimal binding energy (Eb). The density of states of SAAs have been systematically investigated to further discuss structural properties. Based on density functional theory calculations, the activity and selectivity of Ir1/Cu(111) SAAs are investigated for electrocatalytic CO2 reduction reaction (CO2RR). The initial hydrogenation of CO2 on Ir1/Cu(111) SAAs can form *CO intermediates, which will be further to CH4 production by the pathway of *CO → *CHO → *CHOH → *CH2OH → *CH2 → *CH3 → CH4. This study provides theoretical insights for the rational design of selective Cu-based monatomic alloy catalysts.

Engineering Single-Atom Sites with the Irving-Williams Series for the Simultaneous Co-photocatalytic CO2 Reduction and CH3CHO Oxidation.

The bonding effects between 3d transition-metal single sites and supports originate from crystal field stabilization energy (CFSE). The 3d transition-metal atoms of the spontaneous geometrical distortions, that is the Jahn-Teller effect, can alter CFSE, thereby leading to the Irving-Williams series. However, engineering single-atom sites (SASs) using the Irving-Williams series as an ideal guideline has not been reported to date. Herein, alkynyl-linked covalent phenanthroline frameworks (CPFs) with phenanthroline units are developed to anchor the desired 3d single metal ions from d5 to d10 (Mn2+, Fe3+, Co2+, Ni2+, Cu2+, and Zn2+). The Irving-Williams series was employed to accurately predict the bonding effects between 3d transition-metal atoms and phenanthroline units. To verify this, theoretical calculations and experimental results reveal that Cu-SASs/CPFs exhibits higher stability and faster charge-transfer efficiency, far surpassing other metal-SASs/CPFs. As expected, Cu-SASs/CPFs demonstrates a high photoreduction of CO2-to-CO activity (~30.3 μmol ⋅ g-1 ⋅ h-1) and an exceptional photooxidation of CH3CHO-to-CH3COOH activity (~24.7 μmol ⋅ g-1 ⋅ h-1). Interestingly, the generated *O2 - is derived from the process of CO2 reduction, thereby triggering a CH3CHO oxidation reaction. This work provides a novel design concept for designing SASs by the Irving-Williams to regulate the catalytic performances.

Theoretical investigation on gas sensing characteristics of 3d transition metal atom doped C9N7 for toxic gases (CO, NO, NO2, and SO2)

This study investigates the sensing performance of a series of 3d transition metal doped C9N7 sensor structures for four toxic gases (CO, NO, NO2, and SO2). A series of sensor configurations with single and double 3d transition metal atoms doped with C9N7 (TM-C9N7 and TM2-C9N7) are constructed. The stability of the sensor configuration is evaluated by calculating the formation energy and dissolution potential. The stability analysis results indicate that except Sc-C9N7, Mn2-C9N7, and Cr2-C9N7, all sensor configurations have good structural stability. For screened sensor structures with good structural stability, the adsorption energy values of four toxic gases and three common gases (N2, O2, and CO2) are compared to evaluate their selectivity towards toxic gases. Moreover, the recovery times are also calculated to further evaluate the sensing performance. Through comprehensive evaluation, four sensor structures (Fe-C9N7, Cu-C9N7, Zn-C9N7, and Zn2-C9N7) with high selectivity and relatively short recovery time for toxic gases are determined. Among them, Fe-C9N7 is suitable for sensors of toxic gases NO2, and SO2, while Cu-C9N7, Zn-C9N7, and Zn2-C9N7 have good sensing performance for all four toxic gases.

The effect of different transition metal dopants on the magnetic properties of armchair antimonene, phosphorene, and their binary nanoribbons

Binary antimonene-phosphorene, a novel two-dimensional material with a medium band gap, high carrier mobility, and environmental stability, has attracted growing attention due to its wide applications in spintronics. Using density functional theory, we comprehensively investigate and compare the structural and magnetic properties of armchair Sb, P, and binary SbP nanoribbons doped with 3d transition metal atoms (Ti, Cr, Mn, Fe, Co, and Ni) with various concentrations of dopant atoms. We investigated magnetic properties, including magnetic moment, spin polarization, and spin density. It was found that the magnetic properties for single P and Sb nanoribbons do not depend on the substitution position of TM atoms. In contrast, for binary SbP nanoribbons, the substitution of TM atoms in P or Sb positions leads to different behaviors. For example, the magnetization for substitution of Fe and Co atoms in the P position of the binary SbP nanoribbon will be greater than those of the Sb position, but for other impurity atoms, the magnetization of the binary SbP nanoribbon does not strongly depend on the substitution position. The results show that with increasing the number of impurity atoms in the nanoribbon, the magnetic moment increases, except for the nickel atom in the Sb position of the SbP nanoribbon, in which the nanoribbon prefers the ferrimagnetic state. Also, the spin density results show that the magnetism of the doped systems is mainly attributed to the dopant atoms, and the neighboring atoms have a negligible contribution. The findings of antimonene-phosphorene nanoribbons doped with TM atoms may have potential applications in spintronic nanodevices.

Adjustment of ferromagnetism and improvement of the electronic structure of the TiI3 monolayer by the substitutional doping of 3d transition metal atoms: Ab-initio investigation

Two dimensional Van der Waals materials are very attractive for several researchers because of their distinctive properties and their interesting applications in data storage and spintronic devices. Titanium triiodide (TiI3), which is classified among transition metal trihalides (MX3), has received more attention after CrI3 and VI3 monolayers. Here, we explore the structural, electronic and magnetic properties of pure and 3d TM (TM = Sc, V, Cr, Mn and Fe) doped TiI3 monolayer using first-principles calculations, based on the GGA + Ueff approach. We confirmed the dynamic stability of TiI3 monolayer using phonon calculations and the thermal stability of pure and TM-doped TiI3 monolayers by performing AIMD simulation. We further found that the pure TiI3 monolayer is a stable ferromagnetic semiconductor with intrinsic magnetism. The introduction of vacancy defects in the pristine TiI3 monolayer showed that it is desirable to introduce TM atoms into Ti positions, which led to the improvement of its electronic and magnetic properties. The Sc-doped system keeps its semiconductor behavior with a reduction in the width of the band gap, whereas V-, Cr- and Fe-doped TiI3 monolayers turn into half semiconductors (HSC). Even more impressive, the Mn-doped system is found to be a bipolar ferromagnetic semiconductor (BFMS). We applied spin orbit coupling (SOC) on simulated monolayers, and showed that it affected them by changing their band gaps widths, especially in Fe-doped TiI3 monolayer. Furthermore, we found in all doped systems a ferromagnetic stability, an enhancement of the total magnetic moment, up to 10 μB in Cr- and Fe-doped monolayers, high Curie temperatures, up to 260 K, and high magnetic anisotropic energies, especially in Mn-doped TiI3 monolayer which makes it possess a long range ferromagnetic order. These interesting results concerning the electronic and magnetic properties of pure and transition metals-doped TiI3 monolayers are extremely beneficial for tune and enhance electronic and spintronic devices.

Heterokaryotic transition-metal dimers embedded monolayer g-C3N3 as promising anchoring and electrocatalytic materials for lithium-sulfur battery: First-principles calculations

g-C3N3 not only has high content of pyridine nitrogen, but also has a special two-dimensional porous structure, which is an ideal diatomic catalytic host materials. In this work, homonuclear and heteronuclear dual-atom catalysts (DACs, TM-TM@g-C3N3, TM = Mn, Fe, Co, Ni) were constructed using single-layer g-C3N3 as the carrier material of DACs, and their potential as sulfur-hosting materials and electrocatalytic materials for lithium-sulfur batteries was explored through first principles comprehensively. The results show that the coupling between the two metal atoms in heteronuclear DACs can regulate the spin state of each other's d-electrons, so that the anchoring and catalytic effects of heteronuclear DACs on polysulfide are more excellent than that of homonuclear DACs. Co-Mn@g-C3N3, when utilized as the cathode material in lithium-sulfur batteries, offers exceptional properties due to the hybridization between Mn2+ high-spin state d electron and Co2+ half-filled dz2 orbital. This unique interaction not only enables the polysulfide to exhibit the lowest Gibbs free energy during conversion, but also results in the lowest reaction energy barrier of 0.26 eV for the conversion of Li2S2 to Li2S. Furthermore, it is found that when 3d transition metal atoms act as heteronuclear DACs, the coupling between metal ions with high-spin states at the active site and metal ions with empty orbitals or half-full d-electrons has the most significant catalytic effect on polysulfides.

First-principles study on rare earth-based equiatomic quaternary Heusler alloys YbCoCrSb and YbCoTiSn: New candidates for spintronics

We have investigated the structural, mechanical, thermal, electronic, magnetic, and half-metallic properties of new Yb-based EQHAs such as YbCoCrSb and YbCoTiSn using first-principles calculations. We computed the ground state properties of different possible crystal structures and magnetic states. We also calculated their elastic constants and derived mechanical parameters, including bulk, shear, and Young's moduli, as well as Poisson's and Pugh ratios. The electronic structure of both EQHAs shows half-metallic behavior with a spin down band gap of 0.39 eV for YbCoCrSb and 0.30 eV for YbCoTiSn in the GGA-PBE scheme. The estimated total spin magnetic moment has a positive integer value, which is well in accordance with the Slater-Pauling rule of 18. Because of the nearly closed f orbital shell of the Yb atom, the total spin magnetic moment is mainly dependent on 3d transition metal atoms. These alloys exhibit TC > 300 K using the mean field approximation.

Defect engineering of 1T′ MX 2 (M = Mo, W and X = S, Se) transition metal dichalcogenide-based electrocatalyst for alkaline hydrogen evolution reaction

The alkaline electrolyzer (AEL) is a promising device for green hydrogen production. However, their energy conversion efficiency is currently limited by the low performance of the electrocatalysts for the hydrogen evolution reaction (HER). As such, the electrocatalyst design for the high-performance HER becomes essential for the advancement of AELs. In this work, we used both hydrogen (H) and hydroxyl (OH) adsorption Gibbs free energy changes as the descriptors to investigate the catalytic HER performance of 1T′ transition metal dichalcogenides (TMDs) in an alkaline solution. Our results reveal that the pristine sulfides showed better alkaline HER performance than their selenide counterparts. However, the activities of all pristine 1T′ TMDs are too low to dissociate water. To improve the performance of these materials, defect engineering techniques were used to design TMD-based electrocatalysts for effective HER activity. Our density functional theory results demonstrate that introducing single S/Se vacancy defects can improve the reactivities of TMD materials. Yet, the desorption of OH becomes the rate-determining step. Doping defective MoS2 with late 3d transition metal (TM) atoms, especially Cu, Ni, and Co, can regulate the reactivity of active sites for optimal OH desorption. As a result, the TM-doped defective 1T′ MoS2 can significantly enhance the alkaline HER performance. These findings highlight the potential of defect engineering technologies for the design of TMD-based alkaline HER electrocatalysts.

Nitrogen-vacancy-modulated efficient ammonia desorption over 3d TM-anchored BC3N2 monolayer.

Nitrogen fixation using electrochemical methods on the surface of single-atom catalysts (SACs) provides a highly feasible strategy for green and low-energy-consumption ammonia (NH3) production. Herein, using density functional theory (DFT) calculations, we explored in detail the potential of monolayer BC3N2 SACs supported with 3d transition metal (TM) atoms (TM@BC3N2) to facilitate nitrogen reduction. The results revealed that the TM@BC3N2 systems exhibited remarkable catalytic activity in the nitrogen-reduction reaction (NRR). The fine NRR activity was related to the just-right bonding/antibonding orbital interactions between the 2π* of N2 and the d orbitals of the TM ions. The nitrogen-adsorption configurations were found to have different activation mechanisms. In addition, the effects of convectively formed convex nitrogen defects (VN) on the interaction between N2 and VN-TM@BC3N2 and the NRR process of VN-TM@BC3N2 were studied, and it was found that VN could fine-tune the reaction efficiency of the eNRR because after N atom dissociation to form VN, the interaction of TM-C3 was enhanced, and the activation of nitrogen and adsorption of NH3 by the TM-active centers were weakened. The present study can be used as a motivation for further experimental and theoretical research of 2D monolayers as NRR electrocatalysts.

Bifunctional diatomic site catalysts supported by β12-borophene for efficient oxygen evolution and reduction reactions.

Efficient bifunctional catalysts for oxygen evolution and reduction reactions (OERs/ORRs) are of great importance for sustainable and renewable clean energy, especially for metal-air batteries. Herein, we investigated β12-borophene with double-hole sites capped with 3d transition metal atoms to explore its catalyst performance for hydrogen evolution reactions (HERs), OERs and ORRs. It was found that the borophene is a good platform for diatomic site catalysts (DASCs) due to their advantage of stability over the corresponding single-atom catalysts (SACs) or clusters. The HER performance of DASCs on β12-BM was further improved compared to the SAC case. Furthermore, the supported FeNi DASC exhibited good catalytic performance for both OERs and ORRs, the overpotentials for which were 0.43 and 0.55 V, respectively, better than those of the corresponding supported Ni or Fe SAC due to synergistic effects. We herein propose a novel descriptor involving the Bader charges of coordinated atoms explicitly, behaving much better than the d-band center and integrated crystal orbital Hamilton population (-ICOHP) for DASCs. The synergistic effect of Fe-Ni pairs balanced the too strong binding of OH and further activated OH to achieve better catalytic performance. The results of this study can provide theoretical guidance for the design of efficient bifunctional electrocatalysts.

Theoretical probing of monolayer BiI3 as an electrolyte separator and 3d-TM-doped BiI3 as electrocatalysts toward high-performance lithium–sulfur batteries

2D Multifunctional BiI3 has been proposed to serve as an electrolyte separator to block soluble LiPS diffusion with ultrafast Li+ transport channels and as a promising electrocatalyst for improving LiPS conversion by 3d transition metal atom doping.

Structural, Electronic and Magnetic Properties of Silicene Functionalized with 4d TM Atoms

The experimental realization of silicene has ignited a great deal of interest in researching its properties for utilization in device applications. Silicene is composed of a lattice of silicon. As a result, it can be integrated with contemporary circuitry structures, which are predominantly silicon-based. Therefore, investigating its characteristics, especially those of the bandgap, is pivotal. In the present work, the density functional theory approach is employed to examine the structural, electronic and magnetic characteristics of free-standing silicene doped with 4d Transition Metal (TM) atoms. Modelling is done for a 4x4 silicene supercell with a single vacancy. The resulting structure is, thus, doped with 4d transition metal atoms. Doping results in lattice distortion, as evidenced by the variance in Si-TM bond length relative to Si-Si bond length. The shortest bond length is noticed in the instance of Ru doping, thus demonstrating its strongest bonding with Si atoms. Doping causes the structure to become increasingly deformed, as proved by the elevation in buckling height as well. Except for Zr, Ru and Pd, which exhibit semiconductor behaviour, the 4d TM doping in silicene results in metallic characteristics as the bands cross the Fermi level in the majority of the configurations discussed here. A narrow band gap with a range of 2.1 to 252 meV is produced by doping silicene with Zr, Ru, and Pd. Magnetism is demonstrated by Nb, Mo, Tc, and Rh-doped structures, whereas the other structures are nonmagnetic. The presence of magnetism in these structures is primarily due to contributions from Si-3p, TM- 4d/5s orbitals, and their hybridization.

High Spin Magnetic Moments in All-3d-Metallic Co-Based Full Heusler Compounds.

We conduct ab-initio electronic structure calculations to explore a novel category of magnetic Heusler compounds, comprising solely 3d transition metal atoms and characterized by high spin magnetic moments. Specifically, we focus on Co2YZ Heusler compounds, where Y and Z represent transition metal atoms such that the order of the valence is Co > Y > Z. We show that these compounds exhibit a distinctive region of very low density of minority-spin states at the Fermi level when crystallizing in the L21 lattice structure. The existence of this pseudogap leads most of the studied compounds to a Slater-Pauling-type behavior of their total spin magnetic moment. Co2FeMn is the compound that presents the largest total spin magnetic moment in the unit cell reaching a very large value of 9 μB. Our findings suggest that these compounds are exceptionally promising materials for applications in the realms of spintronics and magnetoelectronics.

Ab initio study on electronic structure and magnetism of AlN and InSe monolayer

Based on the first-principle calculations, the magnetism and electronic structures of AlN and InSe monolayers have been investigated. Calculation results show that the system exhibits spin-polarization when the AlN monolayer contains aluminum vacancy (VAl) or nitrogen vacancy (VN), generating magnetic moments of 3.0 μВ and 1.0 μВ, respectively. The formation energy study indicates that VN defects are more likely to be formed than VAl defects. Besides, the 3d transition metal atoms Cr, Mn, Fe, Co, and Ni doped the AlN monolayer, which generated magnetic moments in the order of the atoms 3.0 μВ, 4.0 μВ, 5.0 μВ, 4.0 μВ, and 3.0 μВ, respectively. Mn–Mn is dominated by ferromagnetic coupling at distant distances. Research results express that the InSe film produced a magnetic moment of 1 μВ when the material contained In vacancies (VIn). The magnetism of the film does not change by applying strain.