Large Magnetic Moment Research Articles

Superior EMI shielding effectiveness of light weight and stretchable X-type hexaferrite-poly(vinylidene fluoride) laminated nanocomposite materials

In the present report, X-type hexaferrite-poly(vinylidene fluoride) laminated nanocomposite films have been fabricated by the solution casting method. The coexistence of a large magnetic moment of these X-type hexaferrite nanoparticles and a large electric dipole moment of polar PVDF matrix in the nanocomposite state make them more suitable for a wide range of EMI shielding applications. The high EMI shielding effectiveness of −69.5 dB at 9.9 and 11.7 GHz and −84.8 dB at 12.5 GHz and −83.8 dB at 14.1 GHz by the nanocomposite films have been observed. The high attenuation (>99.999999%) and wide bandwidth offers a completely unique nanocomposite material for the fabrication of affluent Radar Absorbing Materials (RAMs) to perform against the pollution caused by the high frequency EM radiations. Herein, the article also proposes the fabrication of electromagnetic shielding jacket and its application in daily life to combat against EM pollution.

Growth morphology and magnetic properties of Gd adatoms on h-BN template: From single atom to small cluster and monolayer

Atomic assembly of surface-supported nanostructures with high structural stability, large magnetic moment and magnetic anisotropy energy (MAE) hold great potential applications in spintronic and magnetic storage devices. With the changes of deposition coverage of Gd adatoms on the hexagonal boron nitride (h-BN) template, we systemically investigate the low-lying structures and magnetic properties of Gdn (n=1–19) clusters and monolayers (1ML-Gd and 2ML-Gd) by combining various theoretical methods including the spin–orbital coupling (SOC) density functional theory (DFT), abinitio molecular dynamics (AIMD) simulations and lattice dynamical calculations. Favorable adsorption sites and preferable orientations as well as distinguishing electronic structures have been thoroughly explored to reveal the bonding characteristics and growth models of Gd clusters and thin films. We demonstrate that the planar Gd clusters/monolayers deposited on h-BN surface can exhibit the energetically, dynamically, thermally, and thermomagnetically stable at high temperature of 500 K. The Gd-B covalent and ionic bonding interactions instead of Gd-N interactions give the synergetically contributions for stabilizing small clusters on planar h-BN sheet via the hybridizations of Gd-5d and B-2pz orbitals, while Gd-N covalent bonds participate in additionally bonding interaction for the depositions of large clusters on corrugated h-BN sheet due to the transformations from B/N-sp2 to B/N-sp3 hybridizations. Robust ferromagnetic (FM) couplings with large spin magnetic moments about 7.6 μB per Gd atoms are always found to be the ground states. Orbital magnetic moments of −0.10∼−0.37 μB per atom and large MAEs in few meV are primarily contributed by Gd-5d electrons. We propose that the Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction mediated by 5d electrons determines the long-term FM coupling between Gd atoms, and we estimate the Curie temperatures ranging from 150 K to 60 K for different Gd deposited systems. The excellent structural and magnetic stability as well as large magnetic moment and MAEs therefore facilitate Gd cluster and thin film the promising candidates for spintronic applications.

Loop-current charge density wave driven by long-range Coulomb repulsion on the kagomé lattice

Recent experiments on vanadium-based nonmagnetic kagom\'e metals $A$V$_3$Sb$_5$ ($A=$ K, Rb, Cs) revealed evidence for possible spontaneous time-reversal symmetry (TRS) breaking in the charge density wave (CDW) ordered state. The long-sought-after quantum order of loop currents has been suggested as a candidate for the TRS breaking state. However, a microscopic model for the emergence of the loop-current CDW due to electronic correlations is still lacking. Here, we calculate the susceptibility of the real and imaginary bond orders on the kagom\'e lattice near van Hove filling, and reveal the importance of next-nearest-neighbor Coulomb repulsion $V_2$ in triggering the instability toward imaginary bond ordered CDW. The concrete effective single-orbital $t$-$V_1$-$V_2$ model on the kagom\'e lattice is then studied, where $t$ and $V_1$ are the hopping and Coulomb repulsion on the nearest-neighbor bonds. We obtain the mean-field ground states, analyze their properties, and determine the phase diagram in the plane spanned by $V_1$ and $V_2$ at van Hove filling. The region dominated by $V_1$ is occupied by a $2a_0 \times 2a_0$ real CDW insulator with the inverse of Star-of-David (ISD) bond configuration. Increasing $V_2$ indeed drives a first-order transition from ISD to stabilized loop-current insulators that exhibit four possible current patterns of different topological properties, leading to orbital Chern insulators. We then extend these results away from van Hove filling and show that electron doping helps the stabilization of loop currents, and gives rise to doped orbital Chern insulators with emergent Chern Fermi pockets carrying large Berry curvature and orbital magnetic moment. Our findings provide a concrete model realization of the loop-current Chern metal at the mean-field level for the TRS breaking normal state of the kagom\'e superconductors.

Ultrathin high-temperature ferromagnetic rare-earth films: GdScGe and GdScSi monolayers

Two-dimensional (2D) ferromagnetism with robust room-temperature ferromagnetism has sparked intense interest for future miniature information storage devices. However, most 2D ferromagnetic materials have a low Curie temperature. Here, by using density functional theory, two rare-earth monolayers, the GdScSi monolayer and the GdScGe monolayer, were predicted, in which these two monolayers exhibit ferromagnetic orders with large magnetic moments of approximately 7 μB/Gd. Monte Carlo simulations predict Curie temperatures of approximately 470 K and 495 K for the 2D GdScSi monolayer and the GdScGe monolayer, respectively. The spin band calculations show that they are metal. In addition, these two monolayers exhibit dynamical, mechanical, and thermal stabilities. The combination of these novel magnetic properties makes these 2D ferromagnetic crystals promising candidates for high-efficiency spintronic applications.

Tuned electronic and magnetic properties in 3d transition metal doped VCl3 monolayer: a first-principles study

Transition metal trihalides (MX3) are one of the two-dimensional (2D) materials families that have garnered a lot of attention, especially after the first experimental realization of an intrinsic ferromagnetic CrI3 monolayer. The vanadium trichloride VCl3 monolayer, which is a member of this family, has been proven to be a stable Dirac half-metal with exciting properties and intrinsic ferromagnetism. Using first-principle calculations based on the GGA+U method, we have enhanced the spintronic properties of the VCl3 monolayer by tuning its electronic and magnetic properties via substitutional doping with 3d transition metals. We have found that Sc-, Ti-doped VCl3 monolayer systems are ferromagnetic semiconductors with indirect band gaps, while the Cr-doped monolayer is a ferromagnetic semiconductor with a direct band gap. More interestingly, the Mn-doped and Fe-doped VCl3 monolayers exhibited exciting spin gapless semiconducting (SGS) and bipolar ferromagnetic semiconducting (BFMS) properties that are very desirable for spintronic applications. Furthermore, the Cr-, Mn-, and Fe-doped systems have revealed large magnetic moment reaching the value of 4.75 μ B per unit cell, as well as an increased ferromagnetic stability in the Fe-doped case. By possessing these interesting properties, these TM-doped monolayers could be potential candidates for spintronics.

Recent Approaches in Magnetic Nanoparticle-Based Biosensors of miRNA Detection

In recent years, magnetic nanoparticles (MNPs) have been widely used in many fields due to their advantageous properties, such as biocompatibility, easy modifiability, and high chemical stability. One of these areas is the detection of cancer. It is essential to use existing biomarkers, such as microRNAs (miRNAs), for the early diagnosis of this disease. miRNAs are challenging to distinguish and detect in biological samples because they are small, circulating molecules. It is necessary to use more sensitive and feature-rich systems. Thanks to their large surface areas and magnetic moments, MNPs allow easy separation of miRNA at low concentrations from complex samples (urine and blood) and rapid and specific detection in biosensing systems. Here, we discussed the synthesis and characterization methods of MNPs, their stabilization, and MNP-based biosensors in terms of miRNA detection. We considered the challenges and prospects of these biosensor systems in evaluating the development stages, sensitivity, and selectivity.

Excellent 5f-electron magnet of actinide atom decorated gh-C3N4 monolayer.

Atomic functionality of two-dimensional (2D) materials, typically with a controllable doping route for offering regular atomic arrangement as well as excellent magnetism, is crucial for both fundamental studies and spintronic applications. Here, the adsorptions of the 5f-electron actinide series (An = Ac-Am) on porous graphene-like carbon-nitride (gh-C3N4) layers are explored to determine their structural stabilities, electronic nature and magnetic properties using the combination of density functional theory (DFT) calculations, ab initio molecular dynamics (AIMD), Monte Carlo (MC) simulations and chemical bonding analyses. Our investigations reveal that each An atom can be individually adsorbed at the vacancy site of gh-C3N4 sheet with high energetic, thermal and dynamical stabilities, which are rooted in the major interactions of ionic An-N bonding as well as the minor interactions of covalent bonding of An-5f6d states with N-2s2p states. The delocalization of a very few 5f electrons is dependent on whether they occupy the suborbitals that are matching and conducive to hybridize with the ligand orbitals forming the 5f-2s2p covalent bonds. We propose that the Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism plays a determining role for the inter-atomic 5f-5f magnetic exchange via the 6d electrons as the conduction electrons. Large magnetic moment and magnetic anisotropy energy (MAE) from the localized 5f electrons, together with the metallic characteristics owing to the delocalized 6d electrons, render these An-based 2D materials excellent metallic magnets, especially for the U@gh-C3N4 system with the modest magnetic moment of 0.6 μB, large MAE of 53 meV and high Curie temperature (TC) of 538 K.

Chemically induced ferromagnetism near room temperature in single crystal (Zn1-x Cr x )Te half-metal.

Magnetic semiconductors are at the core of recent spintronics research endeavors. Chemically doped II-VI diluted magnetic semiconductors, such as (Zn1-x Cr x )Te, provide a promising platform in this quest. However, a detailed knowledge of the microscopic nature of magnetic ground state is necessary for any practical application. Here, we report on the synergistic study of (Zn1-x Cr x )Te single crystals using elastic neutron scattering measurements and density functional calculations. For the first time, our research unveils the intrinsic properties of ferromagnetic state in a macroscopic specimen of (Zn0.8Cr0.2)Te. The ferromagnetism is onset at T C ∼ 290 K and remains somewhat independent to modest change in the substitution coefficient x. We show that magnetic moments on Zn/Cr sites develop ferromagnetic correlation in the a-c plane with a large ordered moment of μ = 3.08 μ B. Magnetic moment across the lattice is induced via the mediation of Te sites, uncoupled to the number of dopant carriers as inferred from the density functional calculation. Additionally, the ab initio calculations also reveal half-metallicity in x = 0.2 composition. These properties are highly desirable for future spintronic applications.

Lanthanide metal-organic network featuring strong perpendicular magnetic anisotropy.

The coordination of lanthanides atoms in two-dimensional surface-confined metal-organic networks is a promising path to achieve an ordered array of single atom magnets. These networks are highly versatile with plenty of combinations of molecular linkers and metallic atoms. Notably, with an appropriate choice of molecules and lanthanide atoms it should be feasible to tailor the orientation and intensity of the magnetic anisotropy. However, up to now only tilted and almost in-plane easy axis of magnetizations were reported in lanthanide-based architectures. Here we introduce an Er-directed two-dimensional metallosupramolecular network on Cu(111) featuring strong out-of-plane magnetic anisotropy. Our results will contribute to pave avenues for the use of lanthanides in potential applications in nanomagnetism and spintronics.

First-principles study of indium nitride monolayers doped with alkaline earth metals.

Element doping has been widely employed to modify the ground state properties of two-dimensional (2D) materials. In this work, the effects of doping with alkaline earth metals (AEMs) on the structural, electronic, and magnetic properties of indium nitride (InN) monolayers are investigated using first-principles calculations based on density functional theory. In a graphene-like honeycomb structure, the InN monolayer possesses good dynamical and thermal stability, and exhibits an indirect gap semiconductor character with a band gap of 0.37 (1.48) eV as determined by using the PBE(HSE06) functional. A single In vacancy leads to the emergence of a magnetic semiconductor character, where magnetic properties with a large total magnetic moment of 3.00 μB are produced mainly by the N atoms closest to the defect site. The incorporation of AEMs impurities causes local structural distortion due to the difference in atomic size, where Mg and Ca doping processes are energetically most favorable. Half-metallicity is induced by the partial occupancy of the N-2p orbital, which is a consequence of having one valence electron less. In these cases, the total magnetic moment of 1.00 μB mainly originates from N atoms neighboring the dopants. Further increasing the doping level preserves the half-metallic character, where N atoms play a key role on the magnetism of the highly doped systems. Results presented herein suggest the In replacement by AEMs impurities is an effective approach to make prospective spintronic 2D materials from InN monolayers.

Cleavable crystals, crystal structure, and magnetic properties of the NbFe1+xTe3 layered van der Waals telluride.

Transition metal-based two-dimensional nanomaterials with competing magnetic states are at the cutting edge of spintronic and low-power memory devices. In this paper, we present a Fe-rich NbFe1+xTe3 layered telluride (x ≈ 0.5), which shows an interplay of spin-glass and antiferromagnetic states below the Néel temperature of 179 K. The compound has a layered crystal structure, where the NbFeTe3 layers are terminated by the Te atoms and van der Waals gaps. Bulk single crystals grown by chemical vapor transport reactions possess the (1̄01) cleavage plane suitable for the exfoliation of two-dimensional nanomaterials. Combination of high-resolution transmission electron microscopy and powder X-ray diffraction reveals the zigzag ladders of Fe atoms inside the structural layers, as well as complementary zigzag chains of the partially occupied Fe positions in the interstitial region. Fe atoms carry large effective magnetic moment of 4.85(3)μB per atom in the paramagnetic state yielding intriguing magnetic properties of NbFe1+xTe3. They include frozen spin-glass state at low temperatures and spin-flop transition in high magnetic fields indicating promising flexibility of the magnetic system and its potential control by magnetic field or gate tuning in the spintronic devices and heterostructures.

Tunable electrical properties and multiple-phases of ferromagnetic GdS2, GdSe2 and Janus GdSSe monolayers.

With the continuous miniaturization and integration of spintronic devices, the two-dimensional (2D) ferromagnet coupling of ferromagnetic and diverse electrical properties has become increasingly important. Herein, we report three ferromagnetic monolayers: GdS2, GdSe2 and Janus GdSSe. They are bipolar magnetic semiconductors and demonstrate ferroelasticity with a large reversible strain of 73.2%. Three monolayers all hold large magnetic moments of about 8μB f.u.-1 and large spin-flip energy gaps in both the conduction and valence bands, which are highly desirable for applications in bipolar field effect spin filters and spin valves. Our calculations have testified to the feasibility of the experimental achievement of the three monolayers and their stability. Additionally, intrinsic valley polarization occurs in the three monolayers owing to the cooperative interplay between spin-orbit coupling and magnetic exchange interaction. Moreover, we identified square lattices for GdS2 and GdSe2 monolayers. The new and stable square lattices of GdS2 and GdSe2 monolayers show robust ferromagnetism with high Curie temperatures of 648 and 312 K, respectively, and the characteristics of spin-gapless semiconductors. Overall, these findings render GdS2, GdSe2 and Janus GdSSe monolayers promising candidate materials for multifunctional spintronic devices at the nanoscale.

Magnetic ground state of NiCl2/Br2 monolayers encapsulated in UiO-67 MOF, effect of partially filled pores: Ab-initio and Monte Carlo theoretical study

Ab initio calculations are used to study the properties of two dimensional (2D) Transition Metal Halides (TMH, TM=Ni; H = Cl, Br) encapsulated inside a derivative of UiO-67 Metal-Organic Frameworks (MOF). Two monolayers of TMHs (NiCl2 and NiBr2) were isolated from the experimental Crystallographic Information File (CIF) and used in this study. We found that the structure of both monolayers within the MOF (TMH@MOF) have very similar geometries compared to their perfect 2D sheets hypothetically derived from their bulk structures (TMH@bulk) with small distortions in the Metal–Metal (M–M) and Metal–Halide (M–H) bonds. NiCl2 and NiBr2 sheets have a Ferromagnetic (FM) ground state with large intrinsic magnetic moments localized at each metal site. The predicted FM ground state is also confirmed in the magnetic exchange coupling constant (J) calculations between M centers which are found all positive, but non isotropic within each sheet. Weaker interactions with J ≈0.2 meV are found among NN centers in the outer ring compared to J ≈0.85 meV in the inner rings of both monolayers. The calculated Jś are inserted in a Monte Carlo (MC) code to afford Curie temperatures of 27 K and 22 K for NiCl2/Br2 monolayers respectively. Finally, the experimentally collected structures at low metal loading were found to have distinct magnetic properties compared to the completely filled sheets.

Structural, magnetic and transport properties of the quaternary Heusler alloy CoFeMnSn

First-principles calculations have been used to study the structure stability, mechanical properties, dynamic stability, electronic structure, magnetic moment, and anomalous Hall conductivity of the quaternary Heusler alloy CoFeMnSn. It is found that the Type Ⅰ structure is the most energetically favorable configuration, which exhibits high mechanical and dynamic stability. The large experimental saturation magnetic moment of 4.16 μB/f.u. and a high Curie temperature well above room temperature facilitate its application in the field of spintronics. The material’s resistivity changes very little with increasing temperature, showing a weak negative temperature coefficient, indicating a non-metallic transport behavior of the alloy. The main carrier of the alloy is hole with a carrier concentration of roughly 2.49 × 1022 cm−3 at 300 K. The analysis of the anomalous transport properties of the alloy indicates that both intrinsic and extrinsic factors contribute to the anomalous Hall effect of the CoFeMnSn alloy. Although it is difficult to distinguish between the side-jump and intrinsic mechanisms, it is shown that the skew scattering associated with phonons plays a significant role in the anomalous Hall effect.

Antiferromagnetic nodal loop and strain-controllable magnetic phase transition in monolayer MnAl

Exploring novel two-dimensional (2D) materials with intrinsic magnetism or topological band features is a focus of current research. Here, based on first-principles calculations, we study a 2D structure of MnAl, which, in the bulk form, is a well-known permanent magnet. We show that in 2D, MnAl can stabilize in a square lattice with single-atom thickness. The ground state is an antiferromagnet (AFM) with checkerboard type magnetic ordering and an estimated Néel temperature of 60 K. The state has large magnetic moment (∼4 μB per Mn) and sizable anisotropy (∼0.27 meV/f.u.), analogous to bulk MnAl. In the electronic band structure, the state exhibits a single type-I AFM nodal loop at the Fermi level, which is protected by mirror symmetry in the absence of spin–orbit coupling. Spin–orbit coupling opens only a small gap at the loop, preserving the band inversion feature. Furthermore, we show that a small strain (∼1%) can drive a magnetic phase transition from the checkerboard AFM to a stripe-type AFM state, accompanied by a significant change in the band structure. Our result offers an intriguing platform for exploring the interplay among magnetism, topology, and phase transitions in low dimensions.

Multiferroic nitride perovskites with giant polarizations and large magnetic moments

Multiferroics with coupling between ferroelectricity and magnetism have been pursued for decades. However, their magnetoelectric performances remain limited due to the common trade-off between ferroelectricity and magnetism. Here, a family of nitride perovskites is proposed as multiferroics with prominent physical properties and nontrivial mechanisms. Taking GdWN$_3$ as a prototype, our first-principles calculations found that its perovskite phases own large polarizations (e.g. $111.3$ $\mu$C/cm$^2$ for the $R3c$ phase) and a magnetic moment $7$ $\mu_{\rm B}$/Gd$^{3+}$. More interestingly, its ferroelectric origin is multiple, with significant contributions from both Gd$^{3+}$ and W$^{6+}$ ions, different from its sister member LaWN$_3$ in which the ferroelectricity almost arises from W$^{6+}$ ions only. With decreasing size of rare earth ions, the A site ions would contribute more and more to the ferroelectric instability. Considering that small rare earth ions can be primary origins of both proper ferroelectricity and magnetism in nitride perovskites, our work provides a route to pursuit more multiferroics with unconventional mechanisms and optimal performances.

Two-Dimensional Half-Metallic and Semiconducting Lanthanide-Based MXenes.

As a large family of two-dimensional materials, MXenes have attracted intensive attention in recent years. For more functional applications, it is of great significance to determine new MXene members. Here, we theoretically expand the M elements of MXenes to the lanthanide series. Based on density functional theory calculations, the bare lanthanide-based carbides M2C (M = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb) and the corresponding fluorine- and hydroxyl-terminated configurations are investigated. Most of the fluorine- and hydroxyl-terminated MXenes investigated are half-metals. Specifically, in the half-metallic Eu2CF2, the spin-down states show a band gap larger than 2 eV, implying this configuration's potential applications in spin generation and injection. Both Gd2CT2 (T = F and OH) are magnetic semiconductors. The former shows an indirect band gap of 1.38 eV, while the latter presents a direct one of 0.882 eV. These two configurations also show large magnetic moments higher than 13.7 μB per unit cell. All the hydroxyl-terminated MXene members show relatively low work functions, with the lowest value of 1.46 eV determined in Tm2C(OH)2. These predicted electronic properties imply that the lanthanide-based MXenes could have potential applications in spintronics, information storage, near-infrared detectors, field effect transistors, and field emitter cathodes.

Computational study of structural stability, elastic, electronic, magnetic and thermodynamic properties of the Rh2-based full-Heusler compounds: Rh2MnZ (Z = Sn, Pb, Tl) by FP-LAPW method

The structural, elastic, electronic and thermodynamic properties as well as the magnetism of the ternary full-Heusler alloys Rh2MnZ (X = Sn, Pb and Tl) have been investigated by using full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) within the generalized gradient approximation (GGA). The AlCu2Mn-type structure is energetically more favorable than the CuHg2Ti-type structure for all the compounds studied here and found to be are ferromagnetic. The electronic structures calculations are found to exhibit a metallic character for all the herein studied compounds Rh2MnZ (X = Sn, Pb and Tl) alloys. The magnetic properties reveal that the Mn atom is responsible for large magnetic moment. Moreover, the mechanical behavior shows that all studied compounds are mechanically stable, ductile and anisotopic in nature. The elastic and thermodynamic properties for Rh2MnTl compound have not yet been established. The obtained results for various properties of the series of Rh2MnZ (X = Sn, Pb and Tl) are compared with those found experimentally and theoretically.

Synthesis, crystal structure and NMR-study new mononuclear paramagnetic Er (III) complex based on imine derivatives of thiacalix[4]arene

The synthesis, crystal structure and NMR-study of new paramagnetic Er (III) complex based on imine derivatives of thiacalix[4]arene was carried out. Temperature dependences of the 1H NMR spectra of complex Er(III) and calix[4]arene with N-contained substituents (I) have been analyzed using the line shape analysis, taking into account the temperature variation of paramagnetic chemical shifts, within the frame of the dynamic NMR method. Two kinds of molecular dynamics in I are reported for the CDCl3 solution. The first one conformational dynamics is conditioned by the pinched cone A ↔ pinched cone B interconversion with activation free energy ΔG≠(298 K) = 40 ± 3 kJ/mol (observed at low temperature). The second one dynamics is connected with rearrangements in coordination environment (with ΔG≠(298 K) = 58 ± 3 kJ/mol). Due to substantial temperature dependence of paramagnetic shifts, the complex I can be considered as NMR thermosensor reagent for local temperature monitoring. Owing to the large magnetic moments typical for many Ln-ions and especially high value of magnetic anisotropy for Er cation (III) adopting capped trigonal prismatic geometry of coordination sphere one may expect that 1-Er can potentially exhibit SMM behavior.

Electrocatalysis in Li–O2 battery over single-atom catalyst based on g-C3N4 substrate

The development of Li–O2 battery is severely hindered by the sluggish reaction kinetics of the oxygen electrode. Herein, we perform a first-principles study of single transition metal atom supported on g-C3N4 substrate (TM/g-C3N4) as potential single-atom catalyst (SAC) in Li–O2 batteries. Combined electronic analysis and thermodynamic calculations, the electrocatalytic mechanism of TM/g-C3N4 SACs in Li–O2 batteries is elucidated. Due to strong metal-substrate interactions, the TM atom is durably anchored at the unsaturated pyridine N site in the holey g-C3N4 substrate, thereby enabling long cycling stability of the oxygen electrode. Among the fifteen candidates studied, Ru/g-C3N4 SAC exhibits the lowest discharge and charge overpotentials. This behavior can be attributed to the synergistic effect of the moveable d electrons of Ru and electron-rich N coordinators, which results in significant interfacial charges, metallic electrical conductivity, and large spin magnetic moments of the RuN2 active center. This study provides in-depth atomic and electronic insights into the catalytic mechanism of TM/g-C3N4 SACs in Li-O2 batteries.