Room Temperature Magnetization Research Articles

Proximity coupling induced two dimensional magnetic order in EuO-based synthetic ferrimagnets

Proximity effects allow for the adjustment of magnetic properties in a physically elegant way. If two thin ferromagnetic (FM) films are brought into contact, electronic coupling alters their magnetic exchange interaction at their interface. For a low-TC\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$T_C$$\\end{document} rare-earth FM coupled to a 3d transition metal FM, even room temperature magnetism is within reach. In addition, magnetic proximity coupling is particularly promising for increasing the magnetic order of metastable materials such as europium monoxide (EuO) beyond their bulk TC\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$T_C$$\\end{document}, since neither the stoichiometry nor the insulating properties are modified. We investigate the magnetic proximity effect at Fe/EuO and Co/EuO interfaces using hard X-ray photoelectron spectroscopy. By exciting the FM layers with circularly polarized light, magnetic dichroism is observed in angular dependence on the photoemission geometry. In this way, the depth-dependence of the magnetic signal is determined element-specifically for the EuO and 3d FM parts of the bilayers. In connection with atomistic spin dynamics simulations, the thickness of the EuO layer is found to be crucial, indicating that the observed antiferromagnetic proximity coupling is a short-ranged and genuine interface phenomenon. This fact turns the bilayer into a strong synthetic ferrimagnet. The increase in magnetic order in EuO occurs in a finite spatial range and is therefore particularly strong in the 2D limit—a counterintuitive but very useful phenomenon for spin-based device applications.

Above-room-temperature intrinsic ferromagnetism in ultrathin van der Waals crystal Fe3+xGaTe2

Two-dimensional (2D) van der Waals (vdW) magnets are crucial for ultra-compact spintronics. However, so far, no vdW crystal has exhibited tunable above-room-temperature intrinsic ferromagnetism in the 2D ultrathin regime. Here, we report the tunable above-room-temperature intrinsic ferromagnetism in ultrathin vdW crystal Fe3+xGaTe2 (x = 0 and 0.3). By increasing the Fe content, the Curie temperature (TC) and room-temperature saturation magnetization of bulk Fe3+xGaTe2 crystals are enhanced from 354 to 376 K and 43.9 to 50.4 emu·g−1, respectively. Remarkably, the robust anomalous Hall effect in 3-nm Fe3.3GaTe2 indicates a record-high TC of 340 K and a large room-temperature perpendicular magnetic anisotropy energy of 6.6 × 105 J m−3, superior to other ultrathin vdW ferromagnets. First-principles calculations reveal the asymmetric density of states and an additional large spin exchange interaction in ultrathin Fe3+xGaTe2 responsible for robust intrinsic ferromagnetism and higher TC. This work opens a window for above-room-temperature ultrathin 2D magnets in vdW-integrated spintronics.

Electron density mapping using maximum entropy method and room temperature magnetism in Cr3+ substituted SnS2

Electron density mapping using maximum entropy method and room temperature magnetism in Cr3+ substituted SnS2

Synthesis and characterization of (Ba2Zn2Fe12O22)1−x(NiFe2O4)x ferrite composites for antenna applications

A series of (Ba2Zn2Fe12O22)1−x(NiFe2O4)x ferrites (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were successfully synthesized by one-pot coprecipitation route. XRD analysis reveals the formation of Ba2Zn2Fe12O22 and NiFe2O4 composite after sintering calcined precursor powder at 1200 °C/ 4 h. Densification behaviour was evaluated by Archimedes’ principle. Field emission scanning electron microscopy was used to study morphological characteristics. Room temperature magnetization behaviour was evaluated using a vibrating sample magnetometer. In composite, it was observed that the saturation magnetization (Ms) and coercivity (Hc) increased with increasing NiF content. With the increase of NiF in the composite, the permittivity (ε) decreased from 28.6 (for x = 0.2) to 13.6 (for x = 0.8) with the corresponding decrease in dielectric loss (tanδε) at 100 MHz. The permeability (μ) also decreased from 21.3 (x = 0.2) to 17.9 (x = 0.8) with the associated decrease of the magnetic losses (tanδμ) at 100 MHz. Miniaturization factor (n) of 19.2 and characteristic impedance of 1.1 were obtained for x = 0.4 composition at 100 MHz along with low dielectric loss factor (tan δε/ε) and magnetic loss factor (tan δµ/µ). The ferrite resonator antenna was fabricated using FR4 as substrate and ferrite pellet as magneto-dielectric resonator material. The antenna characteristics parameters reflection loss S (1,1) and voltage standing wave ratio (VSWR) were measured by vector network analyser (VNA)

Microwave susceptibility analysis of ultrafast moment dynamics in a multicore magnetic nanoparticle system

Room-temperature magnetization dynamics of multicore magnetic nanoparticles often account for intrinsic dipolar magnetism to behave as a single macrospin at low-frequency regime. Either magnetic particle imaging or hyperthermia benefits from the resulting superparamagnetism in terms of nonlinear magnetization response and relaxation losses at frequencies where the rotation of magnetic moments dominates over Brownian motion for a given sinusoidal field. For this situation, spontaneous thermal relaxation (in the absence of external fields) of each composing particle moment within the cluster is critical to define effective Néel time constant and may intersect with ferromagnetic resonance (FMR) at GHz range. Here, we performed broadband AC susceptometry on both immobilized single-core and multicore iron-oxide nanoparticles up to 26.5GHz under DC bias fields. For each solid sample, we confirmed FMR frequency, where large single-core nanoparticle systems demonstrated typical resonance blueshift as DC field increased. Interestingly, high DC field induced the secondary satellite peak in the imaginary part of AC susceptibility spectra for the case of multicore nanoparticle systems. We further highlighted that a synchronous precession of the polarized macrospins under nonuniform effective fields was responsible for splitting FMR peaks at nearby microwave frequencies. Upon curve fitting of the field-dependent FMR frequency spectra, the Landau-Lifshitz-Gilbert-Kittel model later elaborates on the complex moment dynamics of multicore nanoparticle systems in correlation with distribution functions. Published by the American Physical Society 2024

Room-Temperature CrI3 Magnets through Lithiation.

The pursuit of two-dimensional (2D) magnetism is promising for energy-efficient electronic devices, including magnetoelectric random access memory and radio frequency/microwave magnonics, and it is gaining fundamental insights into quantum sensing technology. The key challenge resides in overseeing magnetic exchange interactions through a precise chemical reduction process, wherein manipulation of the arrangement of atoms and electrons is essential for achieving room-temperature 2D magnetism tailoring in a manner compatible with device architectures. Here, we report an electrochemically crafted CrI3 layered magnet─a van der Waals material─with precisely tailored lithiation and delithiation degrees. The crystalline and packing structure within the intralayer are preserved during the lithium intercalation within the interlayer, owing to weak interlayer coupling. Intrinsic ferromagnetism featuring a Curie temperature reaching 420 K has been unequivocally demonstrated, showcasing a coercivity of 1120 Oe at room temperature. The degree of lithiation through the reduction from Cr3+ to Cr2+ plays a crucial role in determining a 28.5% change in magnetization and a 0.29 eV shift in the bandgap. Room temperature ferromagnetism and magnetoelectricity are critical for noncontact, specifically photon-driven, dynamic magnetism control of 2D magnet-based magnonics devices.

Room-Temperature Magneto-Photoresponse in All-2D Optoelectronic Devices for In-Sensor Vision Systems.

Interplay between magnetism and photoelectric properties introduces the effective control of photoresponse in optoelectronic devices via magnetic field, termed as magneto-photoresponse. It enriches the application scenarios and shows potential to construct in-sensor vision systems for artificial intelligence with gate-free architecture. However, achieving a simultaneous existence of room-temperature magnetism and notable photoelectric properties in semiconductors is a great challenge. Here, the room-temperature magneto-photoresponse is accomplished in all-2D optoelectronic devices, employing 2D ferromagnet Fe3GaTe2 as the source and drain, with WSe2 forming the channel. The interplay between room-temperature magnetism and photoelectric properties is realized by introducing the unique magneto-band structure effect from 2D interface, resulting in magneto-tunable charge transfer between Fe3GaTe2 and WSe2. The photocurrent in this 2D optoelectronic device exhibits robust response to both the direction and amplitude of external magnetic fields. Utilizing constructed 2D optoelectronic devices with magneto-photoresponse, traditional gate-controlled phototransistors are replaced and a prototype in-sensor vision system with visual adaptation, significantly improving the recognition accuracy to over four times in low-contrast environments is established. These findings pave a way for achieving high-temperature magneto-photoresponse, thereby guiding the construction of robust in-sensor vision systems toward high performance and broad applications.

Design of 1.1T/300mm Bitter-type magnet for gyro-traveling-wave tube with power consumption optimization theory.

To improve the portability of magnets in gyrotron devices, we designed a compact Bitter-type magnet with power consumption optimization theory. This magnet operates at room temperature in a small volume. The theory revises existing electromagnetic theory for non-uniform structural Bitter-type magnets and achieves the lowest energy consumption through iterative optimization. To extend the magnetic field homogeneity region, the ferromagnetic material armature is applied to the Bitter-type system without additional power consumption. Unlike previous manual designs, the proposed Bitter-type magnets can obtain optimal parameters with a significant reduction in computing time. Through the introduction of correction factors, we improve accuracy through multiple verifications of simulations and experiments. On this basis, a room-temperature Bitter-type magnet system for Ka-band fundamental mode gyrotron amplifiers is designed. Its maximum magnetic field strength is 1.1T, and the length of the homogeneity region is 300mm. Through optimization, its energy consumption is only 27.5 kW.

Evolution of magnetization of Bi1-ySmyFe1-xTixO3 ceramics at the morphotropic phase boundary attested by multistep magnetization measurements, time aging and electric field

Bi1-ySmyFe1-xTixO3 ceramics with compositions at the rhombohedral- orthorhombic morphotropic phase boundary (y = 0.1, 0.12, 0 ≤ x ≤ 0.1) were prepared by solid state reaction method. Analysis of the crystal structure of the compounds based on the results of laboratory and synchrotron X-ray diffraction measurements as well as Raman spectroscopy experiments revealed a coexistence of the rhombohedral phase (SG R3c) and the anti-polar orthorhombic phase (SG Pbam) in the compounds Bi0.88Sm0.12Fe1-xTixO3 with 0 ≤ x ≤ 0.1; the compounds Bi0.9Sm0.10Fe1-xTixO3 are characterized by the mixed structural state for the concentration range 0 ≤ x ≤ 0.06 and by the single phase rhombohedral state within 0.06 < x ≤ 0.1. Room temperature magnetization measurements demonstrate a gradual increase of remanent magnetization with Ti content in the compounds of both systems up to the maximal value of MR ∼0.28 emu/g for compounds with x = 0.06 which is followed by a decrease in magnetization with further titanium doping. Temperature decrease leads to a reduction of remanent magnetization which is mainly caused by a partial recovery of spatially modulated spin structure occurred in the compounds of both systems. Time aging of the compounds for about ∼1 year leads to a drastic increase of MR, which is caused by a change in the structural phase ratio, homogeneity of the structural state and a contribution of unbounded spins demonstrated by low field measurements. Subjecting of the annealed compounds to external electric field of E ∼40 kV/cm leads to a decrease of magnetization associated with backward structural transformations and redistribution of the local structural defects in the compounds.

Manipulating and investigating the room-temperature magnetic memory phenomenon: The impact of rare-earth ion doping on nickel oxide nanoparticles

This study investigates the relationship between point defect density and magnetic properties in nickel oxide (NiO) nanoparticles (NPs). Specifically, we explore the effects of 0.5 % trivalent rare-earth ion (RE3+: Ce3+, Pr3+, Nd3+, Sm3+, and Dy3+) doping on NiO NPs, considering the influence of RE3+ ionic radius on structural modulation and magnetic properties. Our findings reveal important trends: increased microstrain (0.08 %–0.17 %) and decreased crystalline size (36–17 nm) with increasing ionic radius (r = 0.91 to 1.01 Å), along with a preference for growth along the (1 1 1) plane over (2 0 0). Additionally, multivalent point defects increase with the increase of ionic radius. Substituting Ni2+ site with RE3+ ion promotes nearest-neighbor weak ferromagnetic interaction over next-nearest-neighbor strong antiferromagnetic (AF) interaction. This leads to a redshift of two magnons (2 M) frequency by 50 cm−1 and enhanced room temperature (RT) magnetization (0.23–0.43 emu/g) with increasing ionic radius. Ce-doped NiO (r = 1.01 Å) shows the smallest crystalline size (17 nm), maximum 2 M redshift, and enhanced RT magnetization (0.43 emu/g) based on interacting bound magnetic polaron model. Ce-, Pr-, Nd-, and Sm-doped NiO NPs exhibit RT magnetic memory effects, while Dy-doped NiO NPs (r = 0.912 Å) display AF properties. Our analysis provides valuable insights for designing RT magnetic memory materials with tailored properties through suitable RE3+ ion substitutions.

Magnetoelectric effect of PZT/Ni50.5Mn27.9Ga21.6/PZT laminate composite: design and measurement

In this work we designed an experimental setup based on a double coil and an electromagnet to measure the magnetoelectric effect of a PZT/Ni50.5Mn27.9Ga21.6/PZT laminate composite, made of a bulk single crystal of Ni50.5Mn27.9Ga21.6 shape memory alloy. The shape memory alloy showed a martensitic transformation at 298 K, a Curie temperature at 368 K and room temperature magnetization of 2.87 uB/f.u. Strain response was found to be between 3% and 4% for magnetic fields greater than or equal to 4 kOe. As for the magnetoelectric effect, the induced voltages were moderate, increasing linearly with the frequency. There was a slight change in the magnetoelectric response with the DC applied magnetic field. For low frequencies, the magnetoelectric voltage was on the order of 10 mV and for higher frequencies about 50 mV. The best magnetoelectric coefficient (215 mV/cmOe) was obtained under an AC field of 1 Oe and a static magnetic field of 7 kOe.

Electronic Structure Using Powder XRD and Its Correlation with the Origin of Room-Temperature Magnetism in Cr3+ Doped SnO2

Electronic Structure Using Powder XRD and Its Correlation with the Origin of Room-Temperature Magnetism in Cr3+ Doped SnO2

Orbital Hybridization Induced Dipole Polarization and Room Temperature Magnetism of Atomic Co‐N4‐C toward Electromagnetic Energy Attenuation

AbstractManipulating the electronic structure and geometric coordination environment of single metal atoms has been considered as promising approach for enhancing dipole polarization and enriching electromagnetic attenuation mechanisms. However, achieving precise control of the dielectric polarization response at atomic scale remains a huge challenge. Herein, a metal‐acetate coordination complexes‐assisted strategy is proposed to prepare spatially isolated cobalt (Co) atoms embedded in accordion‐like nitrogen‐doped carbon (NC) matrix. The interactions between metal atoms and NC matrix are carefully tailored through the successive evolution of dispersion states of Co species, ranging from individual atoms to atomic clusters to nanoparticles. Density functional theory reveals that the orbital hybridization between the d electrons of embedded Co atoms and p electrons of coordinated N atoms induces the electron redistribution at N sites, enabling enhanced electric dipole polarization and robust room temperature magnetism (a saturation magnetization of 0.108 emu g−1 at 300 K). Consequently, Co‐SAs@NC exhibits optimal electromagnetic wave absorption properties with a minimum reflection loss of ‐54.4 dB and an effective absorption bandwidth of 8.4 GHz. This work demonstrates an efficient strategy for modulating electromagnetic response at atomic level and provides a novel insight into the d/p electrons orbital hybridization between single metal atoms and NC species.

Synthesis, physico-chemical properties, and AC induction heating of polycaprolactone-coated bio-compatible Fe3O4 nanoparticles

Ex-situ functionalization of Fe3O4 nanoparticles, synthesized using a coprecipitation method, with bio-compatible polycaprolactone (PCL) polymer is reported in this study. The formation of the crystalline structure of Fe3O4 is confirmed from the X-ray diffraction patterns. The presence of the PCL polymer on the surface of the coated MNPs is confirmed using Fourier transform infrared and X-ray photoelectron spectroscopy techniques and thermogravimetric analysis. Scanning and transmission electron microscopy imaging studies reveal the nearly spherical morphology of the synthesized nanoparticles. Room temperature magnetization measurements show the superparamagnetic nature of the PCL coated nanoparticles with high saturation magnetizations varying from ∼61–66 emu/g. Further, the room temperature coercivity is found to be reduced by ∼78 % for the PCL coated nanoparticles, which is attributed to the lowering of the interparticle interactions upon surface functionalization. Magnetic fluid hyperthermia studies on the PCL coated nanoparticles dispersed in ∼1 wt% agar gel shows significant alternating magnetic field induced heating efficiency, with temperature rise in the vicinity of the hyperthermia limit (∼42 °C). The highest specific absorption rate is found to be ∼85.4 ± 3.9 W/gFe, indicating an intrinsic loss power of ∼0.62 nHm2kg−1, which is significantly higher than the previously reported values for PCL coated Fe3O4 MNPs. The field induced heating efficiency is found to be correlated with the saturation magnetization of the PCL coated nanoparticles. In vitro cytotoxicity studies on human breast cancer (MCF-7) cell lines confirm the superior bio-compatibility of the PCL coated Fe3O4 nanoparticles. Superior field induced heating efficiency, coupled with good bio-compatibility makes the PCL functionalized Fe3O4 nanoparticles a potential candidate for magnetic fluid hyperthermia.

Terahertz electric-field-driven dynamical multiferroicity in SrTiO3

The emergence of collective order in matter is among the most fundamental and intriguing phenomena in physics. In recent years, the dynamical control and creation of novel ordered states of matter not accessible in thermodynamic equilibrium is receiving much attention1–6. The theoretical concept of dynamical multiferroicity has been introduced to describe the emergence of magnetization due to time-dependent electric polarization in non-ferromagnetic materials7,8. In simple terms, the coherent rotating motion of the ions in a crystal induces a magnetic moment along the axis of rotation. Here we provide experimental evidence of room-temperature magnetization in the archetypal paraelectric perovskite SrTiO3 due to this mechanism. We resonantly drive the infrared-active soft phonon mode with an intense circularly polarized terahertz electric field and detect the time-resolved magneto-optical Kerr effect. A simple model, which includes two coupled nonlinear oscillators whose forces and couplings are derived with ab initio calculations using self-consistent phonon theory at a finite temperature9, reproduces qualitatively our experimental observations. A quantitatively correct magnitude was obtained for the effect by also considering the phonon analogue of the reciprocal of the Einstein–de Haas effect, which is also called the Barnett effect, in which the total angular momentum from the phonon order is transferred to the electronic one. Our findings show a new path for the control of magnetism, for example, for ultrafast magnetic switches, by coherently controlling the lattice vibrations with light.

Beamline design for multipurpose muon beams at CSNS EMuS

A new muon beam facility, called the Experimental Muon Source (EMuS), was proposed for construction at the China Spallation Neutron Source (CSNS). The design of the complex muon beamlines for the EMuS baseline scheme, which is based on superconducting solenoids, superferric dipoles and room-temperature magnets, is presented herein. Various muon beams, including surface muons, decay muons and low energy muons, have been developed for multipurpose applications. The optics design and simulation results of the trunk beamline and branch beamlines are presented. With a proton beam power of 25 kW at a standalone target station that consists of a conical graphite target and high-field superconducting solenoids, the muon beam intensity in the trunk beamline varies from 107/s for surface muons to 1010/s for high-momentum decay muons. And at the endstations, these values vary from 105/s for surface muons to 108/s for decay muons.

Oxygen ion irradiation-driven Al-vacancy mediated room-temperature magnetism induced in amorphous Al-N-O alloy thin films

In this work, the evolution of superparamagnetism (SPM) at room temperature is observed in the reactive magnetron sputter deposited amorphous Al-N-O alloy thin films after irradiation with oxygen ions (O−). Energy dispersive X-ray (EDX) analysis reveals the presence of notable Al-vacancy (VAl) in as-grown Al-N-O alloy thin film. X-ray photoelectron spectroscopy (XPS) confirms nitrogen trapping at VAl sites for thermodynamic stability, forming the Al(NOy)x phase. Upon the irradiation using O− at low fluence, i.e. 5 × 1013 ions/cm2, mainly VAl-ON complexes emerged. Here ON refers to nitrogen replaced by oxygen. Furthermore, an increase in oxygen fluence from 1 × 1015 to 2 × 1016 ions/cm2 yields the cross-over from VAl-ON complexes to mainly VAl, due to knocking off the trapped nitrogen atoms at VAl sites. From depth-resolved positron beam-based Doppler broadening measurements, the greater density of VAl sites is noticed in the film irradiated with the highest fluence of O− ion, i.e., 2 × 1016 ions/cm2. The correlation between the elevation of VAl sites with O− irradiation dose is in excellent agreement with the emergence of superparamagnetism (SPM) in the films. Hence, the emergence of SPM in the film after irradiation has been attributed to the creation of VAl sites, which leads to a localized magnetic moment.

Development and fabrication of phosphorus-doped ordered mesoporous carbon for highly efficient energy storage of supercapacitor application

In this work, chemical vapor deposition (CVD) using SBA-15 as the template at different temperatures ( 750 - 1000 °C) was used for the fabrication of phosphorus-doped ordered mesoporous carbons (POMCs) for high-performance supercapacitors. The structural formation of the template and POMCs was confirmed using various characterization techniques. Furthermore, the magnetic characteristics of the POMCs were explored using room-temperature field-dependent magnetization studies. Moreover, the supercapacitor performance of the POMCs was evaluated through electrochemical analyses, such as cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) in a 1 M H2SO4 electrolyte medium. Among all POMCs, POMC 900 exhibited a high specific capacitance of 312 Fg−1 at a current density of 0.5 Ag−1 due to a higher Phosphorus content. Furthermore, the symmetric device fabricated using POMC 900 showed 90.8 % coulombic efficiency with 97.5 % capacitance retention after 5000 cycles at 2 Ag−1 of the current density as well. Thus, the CVD synthesis of POMC materials is a highly promising electrode material for cheap and high-performance supercapacitors.

Magnetization reversal and coercivity mechanism in ferrimagnetic M-type hexaferrite by controlling phase evolution

The correlation of phase evolution (annealing at different temperatures) with magnetic properties like magnetization reversal, coercivity mechanism, and energy product in M-type hexaferrite by substituting Sr in place of Ba has been reported in the present article. The Ba1-xSrxFe12O19 (x = 0.0, 0.5, & 1.0) have been prepared by the sol–gel auto-combustion method followed by annealing at different temperatures from 800 °C to 1200 °C. The structural and magnetic properties have been characterized by X-ray diffraction, Field emission scanning electron microscopy, Raman spectroscopy, and Vibrating sample magnetometer. The Rietveld refinement confirms contraction in unit cell parameters by replacing Sr in place of Ba and lattice expansion with increasing annealing temperature. There is no significant effect of substitution on magnetic properties found rather heat treatment affects greatly. The transition from a single domain to multidomain particles and their contribution to initial magnetization curves are analyzed. The differential susceptibility (dM/dH) calculated from room temperature magnetization confirms the existence of a pinning effect during magnetization reversal for samples heat treated below 1200 °C. Secondary phases or grain boundaries are believed to act like pinning centers. This work opens insight into the domain wall motion by microstructure engineering. The coercivity is tuned to 6.09 kOe by controlling the annealing temperature for the Ba1-xSrxFe12O19 (x = 1.0) sample. The maximum energy product (BH)max in the range of 0.94–1.27 MGOe has been achieved.

Turning Nonmagnetic Two-Dimensional Molybdenum Disulfides into Room-Temperature Ferromagnets by the Synergistic Effect of Lattice Stretching and Charge Injection.

Exploring two-dimensional (2D) room-temperature magnetic materials in the field of 2D spintronics remains a formidable challenge. The vast array of nonmagnetic 2D materials provides abundant resources for exploration, but the strategy to convert them into intrinsic room-temperature magnets remains elusive. To address this challenge, we present a general strategy based on surface halogenation for the transition from nonmagnetism to intrinsic room-temperature ferromagnetism in 2D MoS2 based on first-principles calculations. The derived 2D halogenated MoS2 are half-semimetals with a high Curie temperature (TC) of 430-589 K and excellent stability. In-depth mechanistic studies revealed that this marvelous nonmagnetism-to-ferromagnetism transition originates from the modulation of the splitting as well as the occupation of the Mo d orbitals by the synergy of lattice stretching and charge injection induced by the surface halogenation. This work establishes a promising route for exploring 2D room-temperature magnetic materials from the abundant pool of 2D nonmagnetic counterparts.