Room Temperature Ferromagnetism Research Articles

The regulation of perpendicular magnetic anisotropy (PMA) is key to the development of spintronic devices. As a traditional antiferromagnetic insulator with in-plane spin orientation, NiO films have been widely used for exchange bias and field-free spin-orbit torque (SOT) switching applications. However, the growth of a single-crystalline NiO film with PMA remains a big challenge. In this study, high-quality NiO (111) thin flakes with room-temperature ferromagnetism were achieved by chemical vapor deposition. The growth of the thin (thickness: ∼4.0 nm) flakes highly depends on temperature; as temperature increases, homostructures of nanoparticles or nanopyramids on flakes would form due to the enhanced diffusion rate and the requirement to reduce the strain energy. The flakes and homostructures show different magnetic performance, of which the pure flakes exhibit ferromagnetic behavior with a magnetic easy axis of off-plane direction, while the perpendicular anisotropy and magnetic moment attenuate for the flake-particle homostructure, and finally turn to antiferromagnetic order for flake-pyramids. Density functional theory (DFT) calculations further confirm the oxygen vacancy as the main source of the net magnetic moment. This work provides a facile method to prepare high-quality NiO flakes and homostructures and supplies a regulation strategy for the magnetic anisotropy of NiO, which may open novel potential applications in the field of magnon spintronics.

Strain engineering presents a promising pathway for modulating the physical properties of two-dimensional (2D) transition metal dichalcogenides materials. In this study, we investigate the strain-induced magnetic behavior of diamagnetic MoS2 films prepared by the DC magnetron sputtering technique. By applying +1% tensile strain to few-layered MoS2 films (∼3.5 nm), we observe the emergence of room-temperature ferromagnetism with a magnetization saturation of about ∼130 emu/cm3, in stark contrast to bulk films (∼40 nm), which remain diamagnetic under similar conditions. Raman spectroscopy reveals a pronounced reduction in the intensity and the splitting of the E′ mode in 1% strained few-layered films, indicating a possible bond elongation and symmetry breaking under tensile stress. Additionally, x-ray absorption spectroscopy at the Mo M3 edge further confirms a strain-induced electronic structure modification in few-layered films, with no corresponding shift observed in bulk counterparts. Moreover, the strain-induced magnetic and structural changes are largely reversible upon strain release. We attribute the origin of ferromagnetism in few-layered films to the combined influence of tensile strain and defect-assisted bond weakening, which facilitates crystal field transitions within the Mo 4d orbitals. These findings demonstrate that strain engineering can effectively induce and modulate magnetism in 2D materials, providing opportunities for developing strain-controlled spintronic applications.

Manipulating high Curie temperature of Sm/Ag doped ZnO monolayers by first-principles GGA+U study.

Robust room-temperature ferromagnetism and the effect of doping concentration in (Co, Tb) co-implanted GaN films

We reported here the structural, optical, and magnetic properties of Zn1−xCoxO nanorods (NRs) with x = 0.00, 0.025, 0.05, and 0.30 wt%. The Zn1−xCoxO NRs samples were fabricated by electrochemical deposition and given the symbols S0, S1, S2, and S3 for x = 0.00, 0.025, 0.05, and 0.30 wt%, respectively. It is found that all NR samples were grown along the (002) plane and have a hexagonal structure. As the Co level increases up to 0.30 wt%, the crystallite size and the texture coefficient are respectively decreased from 57 nm to 0.98 to 25 nm and 0.70. While the diameter of NRs increased from 347 to 1730 nm. Interestingly, the weight% (wt %) of O was increased with increasing Co level. The optical band gap (Eg) was found to be 3.32 eV for the undoped ZnO NRs (S0) and reduced to 2.24 eV with more increase of Co up to 0.30 wt%. At 300 K, the So and S1 exhibit diamagnetic behavior over the field range. For S2, such behavior became weakly ferromagnetic at H ≤ 2000 Oe and diamagnetic at H > 2000 Oe. In contrast, the S3 exhibits strong ferromagnetic behavior of magnetization (M) = 0.14 emu/g at 20 kOe. However, with decreasing temperature to 10 K, the paramagnetic behavior is dominant for all NRs. However, all NRs samples revealed a hysteresis loop After subtracting the paramagnetic and diamagnetic contributions from the M-H curves. The S2 showed the highest value for coercive field of 256 and 263 Oe, as compared to the other NRs (15–65 Oe). Although S3 shows the softest magnetic properties among all samples (with coercive fields of 15–27 Oe), it exhibits the strongest ferromagnetic behavior. The Zfc/Fc measurements show that all the samples are paramagnetic by nature with no sign for blocking temperature of magnetic nanoparticles. Furthermore, the residual magnetization values measured at 300 K (from both FC and ZFC curves) show a general increasing trend with cobalt doping concentration, with measured values of 6.45 × 10⁻⁹, 2.13 × 10⁻⁴, 8.71 × 10⁻⁵, and 6.45 × 10⁻² emu/g for samples S0 through S3, respectively. This work provides new insights into the correlation between electrochemical growth conditions, defect chemistry, and room-temperature ferromagnetism in Co-doped ZnO systems, advancing beyond previous reports through its demonstration of bandgap tuning and robust ferromagnetism in electrochemically grown NRs and temperature-dependent magnetic phase transitions directly correlated with structural parameters.

Using a microscopic model and the Green's function theory, the size and ion doping dependence of the magnetization, bandgap energy, and polarization of PbTiO 3 nanoparticles have been investigated for the first time. Due to surface oxygen vacancies, the spin exchange interaction constants on the surface are tuned compared to those in the bulk. This leads to room temperature ferromagnetism and to smaller bandgap energy with decreasing the size. By transition metal ion doping at the Ti site, different strain appears, which modifies the exchange interaction constants in the doped compounds. So, on a microscopic level the enhanced magnetization and reduced bandgap energy with increasing the doping concentration are explained. In order to maintain the spontaneous polarization and reduce the bandgap energy, the codoped (Ag,Fe) PTO is also studied. There is a good agreement with the experimental data.

Cadmium telluride (CdTe) is a promising semiconductor for spintronic applications, especially when doped with transition metal (TM) ions. We report here on the structural, electronic, and magnetic properties of Mn and Cr co-doped CdTe, i.e., Cd1−x−yMnxCryTe (x = 0.05, 0.10, 0.15; y = 0, 0.03), thin films grown on (001) GaAs substrates via radio frequency sputtering. High-resolution x-ray diffraction confirms that doping preserves the zinc-blende cubic structure without secondary phases. Atomic force microscopy reveals uniform film morphology. Magnetization measurements and element-specific soft x-ray absorption spectroscopy and x-ray magnetic circular dichroism (XMCD) indicate ferromagnetic ordering induced by Mn and Cr substitution at Cd sites. XMCD measurement reveals that for Mn, the spin, orbital, and total magnetic moments are 0.20–0.52 μB, 0.01–0.05 μB, and 0.19–0.48 μB per Mn, respectively. For Cr, the corresponding values are 0.97–1.01 μB, 0.32–0.41 μB, and 1.30–1.40 μB per Cr atom. The enhanced spin contribution is attributed to the strong sp-d exchange interaction. A significant increase in the total magnetic moment is observed upon Cr co-doping, resulting in a paramagnetic (Mn-only) to ferromagnetic transition due to double-exchange interactions. In Mn and Cr co-doped CdTe, the Mn–Cr interactions enhance magnetic coupling and modify the electronic structures through the strong sp-d exchange interaction between the 3d electrons of Mn2+ and Cr2+ and the host's carrier, stabilizing room temperature ferromagnetism. The first-principles density functional theory calculations using Local Density Approximation + U corroborate experimental findings and predict the half-metallic character in these doped films. The results demonstrate the role of TM co-doping in tailoring ferromagnetism in CdTe, with potential implications for spintronic device applications.

The advancement of nanotechnology has enabled magnetic nanomaterials to exhibit remarkable potential and application value in medicine, transportation, information storage, and spintronics owing to their unique physicochemical properties. In this study, supercritical carbon dioxide (SC CO2) was used to successfully induce room-temperature ferromagnetism in CaSnO3 without magnetic element doping, achieving a maximum saturation magnetization of 0.0727 emu g-1 at 16 MPa. The SC CO2 treatment introduced lattice-scale defects, releasing residual force within distorted SnO6 octahedra, which led to the suppression of structural distortion and drove a structural phase transition from orthorhombic to cubic. Additionally, the enhanced symmetry was accompanied by anisotropic lattice expansion and tensile strain, which thermodynamically lowered the oxygen vacancy formation energy, thereby kinetically driving the creation of more defects. This disrupted the intrinsic antiferromagnetic order and significantly enhanced ferromagnetism. This work elucidates a defect-strain synergy mechanism for tuning material magnetic order, distinguishing it from conventional stoichiometric doping strategies and highlighting the critical role of SC CO2 in material modification.

Room temperature ferromagnetism in ceria nanorods and nanosheets: Influence of morphology and defects

This bibliometric analysis examines research trends in magnetic thin films for spintronic applications from 2001 to 2025, based on 562 documents retrieved from the Web of Science. Our analysis reveals that three key themes dominate the field: magnetoresistance (56 occurrences), magnetic properties (55 occurrences), and thin films (55 occurrences). Research focus has evolved from fundamental studies on giant magnetoresistance and tunnel junctions (2005-2012) to practical applications involving room-temperature ferromagnetism and epitaxial growth (2012-2017), and finally to advanced topics such as anisotropy, spin dynamics, and ferromagnetic resonance (2018-2023). Citation analysis identifies the USA (4151 citations), China (2300 citations), and Japan (1512 citations) as the geographical leaders. At the same time, Nanjing University (71 articles), University of Tokyo (55 articles), and Fudan University (42 articles) are the most productive institutions. Emerging research areas include 2D materials (e.g., graphene and MoS₂) and room-temperature spintronic functionality, which have seen a 65% increase in publications since 2018. This analysis provides a quantitative foundation for advancing spintronic technologies through targeted interdisciplinary approaches.

Freestanding magnetoelectric films fabricated utilizing water-soluble sacrificial layers exhibit significant potential for transformative applications in next-generation technologies and biomedicine. This study presents the fabrication, comprehensive characterization, and multifunctional analysis of BaTiO3 (BTO) and La0.7Sr0.3MnO3 (LSMO) multilayer films. These heterostructures undergo spontaneous morphological transformation into three-dimensional scrolls (3D) or spring-like architectures driven by stress-induced curling mechanisms. A programmable transition from planar, two-dimensional (2D) configurations to self-rolled, three-dimensional magnetoelectric scrolls with tunable diameters is achieved via precise modulation of the relative thicknesses of the BTO and LSMO layers. The resulting freestanding magnetoelectric scrolls exhibit dual functionalities: effective encapsulation of drug simulants, as exemplified by polystyrene microparticles, and the capacity for directed movement at room temperature under ultra-low magnetic field actuation. The fundamental mechanism underpinning this controlled self-assembly arises from the synergistic interaction between strain relaxation after sacrificial layer dissolution and the intrinsic ferroelastic properties of BTO. Concurrently, the room-temperature ferromagnetism inherent to LSMO enables real-time magnetic modulation of scroll deformation dynamics. Biocompatibility assessment via hemolysis assays confirmed the cytocompatibility of these magnetoelectric scrolls. This integrated architecture exhibits considerable potential for multifunctional biomedical applications, including targeted therapeutic delivery, bladder lavage, and thrombus removal. These findings establish freestanding BTO/LSMO magnetoelectric scrolls as promising candidates for the development of next-generation intelligent, stimuli-responsive, and magnetically navigable biomaterials.

Abstract Herein, we report detailed magnetic characteristics of 10-nm thick Q-carbon films grown over a large area. Following the Bloch spin wave theory, we show that Q-carbon exhibits robust room-temperature ferromagnetism with a surprisingly high Curie temperature of ~ 556 K. The square-root dependence of coercivity on temperature indicates homogeneous magnetic interactions in the sample. Finally, through ferromagnetic resonance spectroscopy measurements, we show that the spin interactions in Q-carbon are strong and intrinsic to the system. We envisage that the intrinsic ferromagnetism in Q-carbon opens a new frontier for carbon-based systems in spintronic devices. Graphical abstract

Pressure serves as a fundamental tuning parameter capable of drastically modifying all properties of matter. The advent of diamond anvil cells (DACs) has enabled a compact and tabletop platform for generating extreme pressure conditions in laboratory settings. However, the limited spatial dimensions and ultrahigh pressures within these environments present significant challenges for conventional spectroscopy techniques. In this work, we integrate optical spin defects within a thin layer of two-dimensional (2D) materials directly into the high-pressure chamber, enabling an in situ quantum sensing platform for mapping local stress and magnetic environments up to 3.5 GPa. Compared to nitrogen-vacancy (NV) centers embedded in diamond anvils, our 2D sensors exhibit around three times stronger response to local stress and provide nanoscale proximity to the target sample in heterogeneous devices. We showcase the versatility of our approach by imaging both stress gradients within the high-pressure chamber and a pressure-driven magnetic phase transition in a room-temperature self-intercalated van der Waals ferromagnet, Cr1+δTe2. Our work demonstrates an integrated quantum sensing device for high-pressure experiments, offering potential applications in probing pressure-induced phenomena such as superconductivity, magnetism, and mechanical deformation.

2D MoS2 holds great promise for spintronics, yet is limited by intrinsic diamagnetism. This study demonstrates inducing ferromagnetic behavior in MoS2 films doped with 0.47% Gd, achieving an ultrahigh saturation magnetization of 454 emu/cm3 in a few-layered film over 11-times higher than bulk films (40nm). Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray magnetic circular dichroism, and density functional theory (DFT) calculations reveal an interplay between Gd dopants and Mo, S vacancies (V1Mo+2S), leading to the formation of bound magnetic polarons (BMPs) that drive ferromagnetic ordering. H2S annealing and DFT calculations reveal that defect healing reduces the saturation magnetization by 83%. High sulfur migration barrier in few-layered films helps preserve BMPs, thereby sustaining ferromagnetism, whereas lower migration barriers in bulk films lead to suppression. These findings highlight the synergy between Gd doping and defect engineering in achieving ultrahigh room-temperature ferromagnetism, offering a scalable strategy for developing high-performance 2D magnetic materials for spintronic applications.

Undoped CuO nanostructures and Sb-Bi co-doped CuO nanostructures (at 2% and 4% by weight) were prepared using co-precipitation technique. Powder XRD pattern reveals the monoclinic structure of CuO and shows a shift in diffraction peak of the (111) plane. Changes in morphology like non-uniform rod (2 Wt. %) and flower (4 wt. %) were observed when the co-dopants added. Large number of hopping electrons in grain boundaries at high temperature and frequency enrich the electrical conductivity. All the samples exhibit a narrow hysteresis loop with high magnetization values and low coercivity and retentivity, representing the room temperature ferro-magnetism. The optical limiting (OL) properties improved with increased dopant concentration. The material co-doped with 4 wt.% show a higher nonlinear optical absorption coefficients and lower onset OL threshold value. Consequently, they represent a preferred option for developing laser safety devices, particularly against the highly sensitive Neodymium-doped Yttrium Aluminium Garnet (Nd: YAG) laser.

The discovery of two-dimensional (2D) ferromagnetic semiconductors holds significant promise for advancing Moore's law and spintronics in-memory computing, sparking tremendous interest. However, the Curie temperature of explored 2D ferromagnetic semiconductors is much lower than room temperature. Although plenty of 2D room-temperature ferromagnetic semiconductors have been theoretically predicted, there have been formidable challenges in preparing such metastable materials with ordered structures and high stability. Here, utilizing a novel template-assisted chemical vapor deposition strategy, we synthesized layered MnS2 microstructures within a ReS2 template. The high-resolution atomic structure representation revealed that monolayer MnS2 microstructures well crystallize into a distorted T-phase. Room-temperature ferromagnetism was confirmed through vibrating sample magnetometer measurements, microzone magnetism imaging techniques, and transport characterization. Theoretical calculations indicated that the room-temperature ferromagnetism originates from the Mn-Mn short-range interaction. Our observation not only offered the experimental confirmation of the intrinsic room-temperature ferromagnetism in layered MnS2, but also provided an innovative strategy for the growth of 2D metastable functional materials.

Achieving room‐temperature ferromagnetism (RTFM) in diluted magnetic semiconductors (DMSs) has been a long‐standing challenge, with doping transition metals (TM) into oxide semiconductors being one of the most common approaches. However, the underlying physical mechanisms remain poorly understood, particularly for Co‐doped ZnO (Co:ZnO) films, which exhibit high Curie temperatures (Tc) above 300 K. A promising mechanism proposed for high‐Tc ferromagnetism is the donor impurity band exchange model, in which donor electrons mediate the coupling between TM spins. Despite its theoretical significance, the nature of the donor band electrons has yet to be experimentally identified. In this work, we use polarization‐dependent, bulk‐sensitive hard x‐ray photoemission spectroscopy (HAXPES) to investigate Co‐doped ZnO epitaxial films. Our results reveal the presence of a weak electron donor band, crossing the Fermi level, and from a polarization dependence analysis, it is unambiguously identify it as having “s‐character.” This finding offers new insight into the ferromagnetic mechanism in Co‐doped ZnO, where Zn1+4s1 states mediate the ferromagnetism, contributing to metallic‐like transport and Co2+ spin ordering. These results not only elucidate the complementary role of dopant‐host electronic states but also open avenues for designing novel room‐temperature magnetic semiconductors, particularly in the context of 2D DMSs.

Abstract The emergence of room temperature ferromagnetism (RTFM) in thin films of semiconducting oxides has attracted significant interest due to its promising applications in spintronic and multifunctional electronic devices. Ferromagnetism (FM) in ultrathin layers of magnetic transition-metal oxides and in thin films of undoped oxide semiconductors typically arising from low dimensionality and the formation of surface-related vacancies and defects, makes them attractive for spintronics applications. The primary objective of this research is to investigate the magnetism in ultrathin rare-earth oxide films as a function of dimensionality. In this study, we report the structural and magnetic properties of Gd2O3 thin films grown on LaAlO3 (LAO) substrates using the pulsed laser deposition (PLD) technique. Room-temperature M–H measurements show a significant ferromagnetic response in the out-of-plane direction compared to the in-plane direction. As the Gd2O3 film thickness increases, the ferromagnetic features gradually diminish, and at higher thicknesses (t > 72 nm), a paramagnetic-like behavior is observed, similar to that of bulk Gd2O3 samples. The observed RTFM behaviour in PLD-grown Gd2O3 thin films is attributed to surface oxygen vacancies, as revealed by X-ray photoelectron spectroscopy (XPS) analysis. This study highlights the achievement of the RTFM in Gd2O3 thin films, which holds potential for future spintronic applications.

Two-dimensional (2D) crystals which present unconventional stoichiometries on graphene surfaces in ambient conditions, such as Na2Cl, Na3Cl, and CaCl, have attracted significant attention in recent years due to their electronic structures and abnormal cation–anion ratios, which differ from those of conventional three-dimensional crystals. This unconventional crystallization is attributed to the cation–π interaction between ions and the π-conjugated system of the graphene surface. Consequently, their physical and chemical properties—including their electrical, optical, magnetic, and mechanical characteristics—often differ markedly from those of conventional crystals. This review summarizes the recent progress made in the fabrication and analysis of the structures, distinctive features, and applications of these 2D unconventional stoichiometry crystals on graphene surfaces in ambient conditions. Their special properties, including their piezoelectricity, metallicity, heterojunction, and room-temperature ferromagnetism, are given particularly close attention. Finally, some significant prospects and further developments in this exciting interdisciplinary field are proposed.

Abstract Realizing ferromagnetic semiconductors with high Curie temperature T C is still a challenge in spintronics. Recent experiments have reported two-dimensional (2D) room temperature ferromagnetic metals, such as monolayer Cr3Te6. In this paper, by the density functional theory (DFT) calculations, we proposed a way to obtain 2D high T C ferromagnetic semiconductors through element replacement in these ferromagnetic metals. We predict that monolayer (Cr4/6, Mo2/6)3Te6, created via element replacement in monolayer Cr3Te6, is a room-temperature ferromagnetic semiconductor exhibiting a band gap of 0.34 eV and a T C of 384 K. Our analysis reveals that the metal-to-semiconductor transition stems from the synergistic interplay of Mo-induced lattice distortion, which resolves band overlap, and the electronic contributions of Mo dopants, which further drive the formation of a distinct band gap. The origin of the high T C is traced to strong superexchange coupling between magnetic ions, analyzed via the superexchange model with DFT and Wannier function calculations. Considering the fast developments in fabrication and manipulation of 2D materials, our theoretical results propose a way to explore the high temperature ferromagnetic semiconductors from experimentally obtained 2D high temperature ferromagnetic metals through element replacement.