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Nanostructures possessing plasmonic and magnetic properties can enhance the transverse magneto-optical Kerr effect (TMOKE) by exciting surface plasmon resonances (SPRs). This provides a promising platform for magneto-optical SPR sensors with significantly improved sensing performance. Here, we propose a high-performance magneto-optical SPR sensor, which consists of a bilayer Au/Co grating placed on a gold film. By tuning the structural parameters, a Fano-like TMOKE spectrum with a linewidth of only 0.0135 nm and an amplitude approaching the theoretical maximum is obtained. We attribute the optimal TMOKE signal achieved by the sensor to the critical coupling concept which is associated with the trade-off between scattering and intrinsic decay rates of the system. The optimized nanostructure sensor demonstrates a sensitivity of 1432 nm/RIU to refractive index fluctuations as small as 0.0001 in air, and all figures of merit (FOM) up to 105 RIU−1, making it suitable for gas sensor fabrication. [ABSTRACT FROM AUTHOR]

Magnetic gels with embedded micro-/nano-sized magnetic particles in cross-linked polymer networks can be actuated by external magnetic fields, with changes in their internal microscopic structures and macroscopic mechanical properties. We investigate the responses of such magnetic gels to an external magnetic field, by means of coarse-grained molecular dynamics simulations. We find that the dynamics of magnetic particles are determined by the interplay of magnetic dipole–dipole interactions, polymer elasticity, and thermal fluctuations. The corresponding microscopic structures formed by the magnetic particles, such as elongated chains, can be controlled by the external magnetic field. Furthermore, the magnetic gels can exhibit reinforced macroscopic mechanical properties, where the elastic modulus increases algebraically with the magnetic moments of the particles in the form of ∝ (m − m c ) 2 when magnetic chains are formed. This simulation work can not only serve as a tool for studying the microscopic and the macroscopic responses of the magnetic gels, but also facilitate future fabrications and practical controls of magnetic composites with desired physical properties. [ABSTRACT FROM AUTHOR]

The effects of sintering temperature (Ts) and chemical substitution on the structural and magnetic properties of manganite compounds L a 1 − x S r x M n 1 − y F e y O 3 (0.025 ≤ x ≤ 0.7 ; y = 0.01 , 0.15) are explored in a search to optimize their magnetocaloric properties around room temperature. A ferromagnetic (FM) to paramagnetic (PM) phase transition is observed at a Curie temperature Tc that can be controlled to approach room temperature by Sr and Fe substitution, but also by adjusting the sintering temperature Ts. Accordingly, the magnetic entropy change (− Δ S M ) quantifying the magnetocaloric effect (MCE) presents a peak at or close to Tc that shifts and broadens with both Sr and Fe doping and is further tuned with sintering temperature. Altogether, we show that it is possible to adjust the strength and dominance of the ferromagnetic coupling in these ceramics, but also using disorder as a tool to broaden and adjust the temperature range with a significant magnetic entropy change. [ABSTRACT FROM AUTHOR]

Room temperature ferromagnetism observed in polycrystalline MnGeP2 bulk samples was investigated by different experimental techniques. The magnetization measurements show a high temperature ferromagnetic phase with a critical temperature TC = 294.0 K and a low temperature magnetic phase transition at TN = 40.5 K. As these parameters (TC,TN) correspond to those of MnP, a ferromagnetic half-metal, whose composition of the samples was further characterized by x-ray diffraction and Rutherford backscattering measurements. They confirmed the presence of orthorhombic MnP precipitates. Electron paramagnetic resonance (EPR) and ferromagnetic resonance (FMR) measurements in the temperature range of T = 4 K to T = 380 K confirm the attribution of the magnetic phase to MnP and show no additional EPR or FMR signal associated with MnGeP2. We conclude that the magnetic properties of the polycrystalline MnGeP2 bulk samples grown by the horizontal gradient freeze technique are dominated by MnP inclusions and that phase pure chalcopyrite MnGeP2 is not ferromagnetic in contrary to previous reports. [ABSTRACT FROM AUTHOR]

Quasi-one-dimensional topological materials have emerged as a captivating area of research due to their interesting electronic properties and potential applications. NbNiTe 5 is one such quasi-1D material. In this work, we report the synthesis, structural characterization, and comprehensive investigation of the electrical transport and magnetic properties of NbNiTe 5. NbNiTe 5 crystallizes in the orthorhombic crystal system with the C m c m space group. Experimental studies have uncovered metallic nature with a remarkably high residual resistivity ratio of 103, along with intriguing spin–orbit interaction-driven nonsaturating magnetotransport properties at low temperatures. A meticulous analysis incorporating magnetoconductivity measurements unveils signatures of weak anti-localization analyzed by using the Hikami–Larkin–Nagaoka formula. Furthermore, the de Haas–van Alphen oscillations demonstrate the high mobility of charge carriers with a significantly low effective mass at five frequencies: F α = 84.82 T, F β = 131.21 T, F γ = 242.36 T, F δ = 31.93 T, and F δ ′ = 162.33 T. In light of these collective findings, NbNiTe 5 can be defined as a quasi-1D topological semimetal. [ABSTRACT FROM AUTHOR]

The effects of sintering temperature (Ts) and chemical substitution on the structural and magnetic properties of manganite compounds L a 1 − x S r x M n 1 − y F e y O 3 (0.025 ≤ x ≤ 0.7 ; y = 0.01 , 0.15) are explored in a search to optimize their magnetocaloric properties around room temperature. A ferromagnetic (FM) to paramagnetic (PM) phase transition is observed at a Curie temperature Tc that can be controlled to approach room temperature by Sr and Fe substitution, but also by adjusting the sintering temperature Ts. Accordingly, the magnetic entropy change (− Δ S M ) quantifying the magnetocaloric effect (MCE) presents a peak at or close to Tc that shifts and broadens with both Sr and Fe doping and is further tuned with sintering temperature. Altogether, we show that it is possible to adjust the strength and dominance of the ferromagnetic coupling in these ceramics, but also using disorder as a tool to broaden and adjust the temperature range with a significant magnetic entropy change. [ABSTRACT FROM AUTHOR]

Room temperature ferromagnetism observed in polycrystalline MnGeP2 bulk samples was investigated by different experimental techniques. The magnetization measurements show a high temperature ferromagnetic phase with a critical temperature TC = 294.0 K and a low temperature magnetic phase transition at TN = 40.5 K. As these parameters (TC,TN) correspond to those of MnP, a ferromagnetic half-metal, whose composition of the samples was further characterized by x-ray diffraction and Rutherford backscattering measurements. They confirmed the presence of orthorhombic MnP precipitates. Electron paramagnetic resonance (EPR) and ferromagnetic resonance (FMR) measurements in the temperature range of T = 4 K to T = 380 K confirm the attribution of the magnetic phase to MnP and show no additional EPR or FMR signal associated with MnGeP2. We conclude that the magnetic properties of the polycrystalline MnGeP2 bulk samples grown by the horizontal gradient freeze technique are dominated by MnP inclusions and that phase pure chalcopyrite MnGeP2 is not ferromagnetic in contrary to previous reports. [ABSTRACT FROM AUTHOR]

The Mn3AgN-based manganese nitrides have attracted continuous attention due to the interesting functional properties, which is closely correlated with the magnetic evolution coupling with structural and electrical order. However, the attention on the fundamental magnetic behavior of the Mn3AgN matrix is still insufficient up to now. Here, the magnetic properties of Mn3AgN have been investigated by comprehensive magnetic measurements including dc magnetization, ac susceptibility, and magnetic relaxation. The results show that Mn3AgN undergoes two magnetic transitions with decreasing temperature: the transition from paramagnetic to antiferromagnetic (AFM) state at ∼285 K and from AFM to spin-glass-like (SGL) state at ∼110 K. The SGL state is essentially a mixed magnetic state of weak short-range ferromagnetic order and spin glass, and its appearance should be related to the AFM configuration of Γ4g with ferromagnetic component. The unique low-temperature magnetic structure of Mn3AgN makes it exhibit interesting low temperatures magnetic behavior, such as the magnetic irreversibility phenomenon, magnetic relaxation behavior, and so on. [ABSTRACT FROM AUTHOR]

High-performance and stable spintronic devices have garnered considerable attention in recent years. Based on first-principle and Monte Carlo calculations, we demonstrate that under reasonable carrier doping, H-VSe2 exhibits 100% spin polarization, a magnetic anisotropy energy of 581 μeV, a tunable easy-axis, and a Curie temperature of 330 K. Moreover, Dzyaloshinskii–Moriya interactions in H-VSe2 and magnetic hysteresis loops are determined theoretically for the first time, which provides more precise and comprehensive descriptions of its magnetic properties under finite temperatures and external magnetic field. This work suggests that H-VSe2 is a powerful candidate for spintronic devices, and it provides solid theoretical support for future experiments. [ABSTRACT FROM AUTHOR]

We examine structural and magnetic properties of a series of La–Fe–Si alloys in the region of concentrations where they naturally form two-phase LaFeSi–LaFe13−xSix composites with variable content and connectivity of LaFe13−xSix grains distributed within the LaFeSi matrix. Theoretical calculations confirm that the LaFeSi constituent is magnetically and structurally inert below room temperature and at pressures between −10 and 10 GPa. The LaFe13−xSix constituent, on the other hand, is magnetically and structurally active: it exhibits first-order magnetostructural transformations that, in addition to xSi, can be controlled with temperature, magnetic field, and pressure. In composites where the concentration of the inactive constituent is ∼70 wt. % or greater, the standard, single-step, LaFe13−xSix first-order phase transformation proceeds in two steps separated by over 30 K in a zero magnetic field. Increasing the magnetic field recouples the two steps and restores the single-step phase transformation pathway. We analyze the roles of stresses caused by both thermal expansion mismatch and the first-order magnetic phase transition in LaFe13−xSix to rationalize the observed physical behaviors that emerge as the temperature or/and magnetic field vary. [ABSTRACT FROM AUTHOR]

Neodymium (Nd) magnets (Nd 2 Fe 14 B) are key materials for achieving high energy conversion efficiency. The coercive forces (fields) of the magnets are often reinforced by adding dysprosium (Dy), especially at high temperatures. To understand the magnetic properties of Dy-substituted systems (Nd 1 − x Dy x) 2 Fe 14 B, it is important to study those of Dy 2 Fe 14 B and Nd 2 Fe 14 B and analyze the difference in detail from a microscopic viewpoint. Applying a recently developed atomistic model approach, we investigated thermodynamic properties of these magnets. We studied the temperature and field dependences of the magnetizations, and anisotropy fields and energies. We found that the simulation results captured the characteristic features of the experimentally observed data. We discuss the detail with the magnetization profiles of the component atoms. Furthermore, we investigated the effect of Dy random substitution on the coercivity in two systems: one in contact with vacuum and the other in contact with a grain boundary phase. We found that the threshold fields increased almost linearly with the concentration of Dy atoms in both systems, which was compared to the results of the layer-by-layer substitution effect analyzed in our previous work. We discuss the influence of the arrangement of Dy atoms on coercivity enhancement. [ABSTRACT FROM AUTHOR]

We investigated the magnetic properties of Sendust (Fe-Al-Si) alloys not only at 0 K but also at finite temperatures by means of the first-principles calculations assuming A2, B2, and D 0 3 structures. We confirmed that the itinerant characteristics of 3 d electrons of Fe are not negligible and a significantly small exchange stiffness constant exists at zero temperature in a B2 structure. However, the calculated Curie temperatures are in the same order for all structures; this indicates that the Curie temperature cannot be determined only by the exchange interactions at zero temperature in itinerant electron systems. Temperature dependence of the exchange interaction, namely, spin configuration dependence, also might be important for determining it. In addition, this property might also be related to the unique behavior of the temperature dependence of the exchange stiffness constant for the B2 structure, which does not decrease monotonically as temperatures increase, contrary to the behavior expected from the Heisenberg model. In addition, we investigated composition dependence on the exchange stiffness constant at zero temperature and confirmed that the substitution of Si with Al could improve the amplitude of the exchange stiffness constant at zero temperature for all structures. [ABSTRACT FROM AUTHOR]

We introduce a novel water bath hydrogenation process designed to enhance the magnetic properties and hyperfine field of Y2Fe17. The core of this process lies in the successful preparation of a new compound Y2Fe17H3.5 by introducing hydrogen in a mild water bath environment, accomplished by a chemical reaction between calcium, Y2Fe17, and ammonium acetate solution at room temperature and pressure. After hydrogen doping, cell volume expansion increased from 778.511 to 795.383 Å3, and notably, lattice expansion is anisotropic. Furthermore, saturation magnetization is increased from 103 to 134.93 emu/g, Curie temperature is increased from 320 to 461 K, and the average hyperfine field is increased from 18 to 25 T. The improvement in magnetic properties is due to the increase in Fe–Fe distance, which according to the Bethe–Slater curve leads to stronger Fe–Fe exchange interactions and enhancing ferromagnetic interactions. This work not only proposes the novel rhombohedral Y2Fe17H3.5 with excellent magnetic properties, but also provides a new method for hydrogen doping in Y2Fe17 which lays the foundation of fundamental solid state physics for further research. [ABSTRACT FROM AUTHOR]

Magnetic and magnetocaloric properties of L a 0.85 S r 0.15 M n 0.99 F e 0.01 O 3 perovskite oxides are investigated in the framework of the mean-field theory with a goal to develop a comprehensive model with parameters that can be used to optimize the caloric performances for cooling applications. Using the experimental magnetic isotherms M(H,T), we estimate and compare the exchange parameter (λ) , the saturation magnetization (M 0) , the total angular momentum (J) , and the gyromagnetic factor (g) for two different samples annealed at 1170 and 1250 °C. These parameters are used, in turn, in the simulation of the magnetic and the magnetocaloric properties of these L a 0.85 S r 0.15 M n 0.99 F e 0.01 O 3 compounds assuming imperfect samples with compositional and/or magnetic inhomogeneities. For this purpose, a Gaussian distribution of the Curie temperature is assumed. The temperature dependence of the magnetic entropy change, − Δ S M (T) , resulting from an applied field variation is simulated for both samples. The selected distribution captures the rounding of the − Δ S M (T) peak at its maximum and its broadening with growth conditions, features that are constantly observed in many bulk polycrystalline compounds. [ABSTRACT FROM AUTHOR]

In this paper, the effects of hydrostatic stress on the magnetic properties of Mn-Zn power ferrites are discussed. Ring cores were embedded in cement and the curing process gradually exerted pressure on the core. A novel testing method was developed to continuously measure the power losses and the magnetic susceptibility in dependence on magnetic excitation at a fixed frequency and room temperature with a vector network analyzer. After 450 h, a maximum compressive stress of 120 MPa was reached. Power loss up to 300% was observed, while magnetic susceptibility dropped by 35%. The magneto-mechanical effect on core losses was simulated with the Hodgdon–Esguerra hysteresis model, showing excellent agreement with tested results, which allows us to predict the behavior of ferrite tiles embedded in load-bearing surfaces for wireless power transfer (WPT) applications. [ABSTRACT FROM AUTHOR]

In this paper, we have studied the effect on the structure and magnetic properties of partial Pd substitution by Gd in Fe–Pd thin films of nominal composition Fe56Pd44−xGdx (x = 1, 3, 5, and 7), deposited onto Si(100) and Si(100)/SiO2 substrates by thermal evaporation. Several techniques contribute to the characterization of their microstructure and magnetic properties, such as x-ray diffraction (XRD), scanning electron microscopy, alternating gradient field magnetometry, and magnetic force microscopy (MFM). X-ray diffraction shows that the as-deposited films are either amorphous or contain a disordered FePd phase, depending on the film thickness. The transformation of disordered fcc-FePd into ordered fct-FePd has been induced by a heat treatment at 530 °C for 4 h. The addition of gadolinium leads to a reduction in the coercivity as a consequence of the emergence of soft phases and of the progressive reduction of the fct-FePd phase, which is primarily responsible for the observed maze magnetic domains. The exchange coupling between the soft phase and the hard fct-FePd phase is demonstrated by first-order reversal curves (FORCs). [ABSTRACT FROM AUTHOR]

Rare-earth doped materials are of immense interest for their potential applications in linear and nonlinear photonics. There is also intense interest in sub-nanometer gold clusters due to their enhanced stability and unique optical, magnetic, and catalytic properties. To leverage their emergent properties, here we report a systematic study of the geometries, stability, electronic, magnetic, and linear and nonlinear optical properties of Au5RE (RE = Sc, Y, La–Lu) clusters using density-functional theory. Several low-energy isomers consisting of planar or non-planar configurations are identified. For most doped clusters, the non-planar configuration is energetically favored. In the case of La-, Pm-, Gd-, and Ho-doped clusters, a competition between planar and non-planar isomers is predicted. A distinct preference for the planar configuration is predicted for Au5Eu, Au5Sm, Au5Tb, Au5Tm, and Au5Yb. The distinction between the planar and non-planar configurations is highlighted by the calculated highest frequencies, with the stretching mode of the non-planar configuration predicted to be stiffer than the planar configuration. The bonding analysis reveals the dominance of the RE-d orbitals in the formation of frontier molecular orbitals, which, in turn, facilitates retaining the magnetic characteristics governed by RE-f orbitals, preventing spin-quenching of rare earths in the doped clusters. In addition, the doped clusters exhibit small energy gaps between frontier orbitals, large dipole moments, and enhanced hyperpolarizability compared to the host cluster. [ABSTRACT FROM AUTHOR]

The microstructure morphology, static magnetic properties, and electromagnetic absorption characteristics of nano FexCoNi alloy particles prepared by chemical liquid deposition with five different Fe content levels are investigated in this paper. The results show that spherical FexCoNi alloy particles with an average particle size of about 100–200 nm and a face-centered cubic crystal structure were obtained. All five samples exhibited soft magnetic behavior, with the saturation magnetization intensity showing an increasing-then-decreasing trend with increasing Fe content, peaking at 141.8 emu/g for Fe content x = 1.0. The dielectric constants (real and imaginary parts) of the prepared alloy particles exhibit significant differences with respect to the variation of Fe content, while the changes in the real and imaginary parts of the magnetic permeability show less pronounced effects with increasing Fe content. As the electromagnetic wave frequency increases, the real parts of the dielectric constants for all composites show minimal fluctuations, and the real parts of the magnetic permeability exhibit a decreasing trend. Moreover, the imaginary parts of the dielectric constants and magnetic permeability show an increasing followed by a decreasing trend as the frequency rises. The material with Fe content x = 1 demonstrated optimal dielectric loss performance and relatively excellent magnetic loss performance, with a sample thickness of 1.9 mm exhibiting the highest reflection loss (RLmax) of −24.2 dB and an effective absorption bandwidth of 4.48 GHz. [ABSTRACT FROM AUTHOR]

VO2 is renowned for its electric transition from an insulating monoclinic (M1) phase, characterized by V–V dimerized structures, to a metallic rutile (R) phase above 340 K. This transition is accompanied by a magnetic change: the M1 phase exhibits a non-magnetic spin-singlet state, while the R phase exhibits a state with local magnetic moments. Simultaneous simulation of the structural, electric, and magnetic properties of this compound is of fundamental importance, but the M1 phase alone has posed a significant challenge to the density functional theory (DFT). In this study, we show none of the commonly used DFT functionals, including those combined with on-site Hubbard U to treat 3d electrons better, can accurately predict the V–V dimer length. The spin-restricted method tends to overestimate the strength of the V–V bonds, resulting in a small V–V bond length. Conversely, the spin-symmetry-breaking method exhibits the opposite trends. Each of these two bond-calculation methods underscores one of the two contentious mechanisms, i.e., Peierls lattice distortion or Mott localization due to electron–electron repulsion, involved in the metal–insulator transition in VO2. To elucidate the challenges encountered in DFT, we also employ an effective Hamiltonian that integrates one-dimensional magnetic sites, thereby revealing the inherent difficulties linked with the DFT computations. [ABSTRACT FROM AUTHOR]

Element substitution of BaTiO 3 -based compounds has been demonstrated as a powerful way for designing novel electronic materials (such as polar metals and multiferroics). To trigger magnetism into ferroelectric BaTiO 3 , general substituted elements are magnetic transition metals (such as Mn, Fe, and Co). The doping effect of rare-earth elements (such as Dy) in BaTiO 3 -based compounds was barely investigated. Here, we report the coexistence of magnetism and electric polarization in epitaxial Dy 0.5 Ba 0.5 TiO 3 films. The single-crystalline films were synthesized by high-pressure magnetron sputtering. The crystal and electronic structures were characterized by high-resolution x-ray diffraction, x-ray photoemission spectroscopy, and resonant soft x-ray absorption spectroscopy. Room-temperature electric polarization was demonstrated by optical second-harmonic generation. Temperature-dependent magnetic hysteresis loops were measured to reveal the revolution of magnetism on temperature. Surprisingly, it is uncovered that the Curie temperature of electric-polarized Dy 0.5 Ba 0.5 TiO 3 films is around 100 K, far above the critical temperature of non-polarized DyTiO 3 (near 60 K). Our work provides another view to understand the magnetoelectric materials. [ABSTRACT FROM AUTHOR]

The effect of the YBCO superconducting (SC) state on the magnetic properties of as-grown YBCO/Co/IrMn heterostructures has been systematically studied using magnetometry and ferromagnetic resonance. The obtained data showed that the superconductivity of the YBCO substrate strongly affects the ferromagnetic properties of the deposited Co layer deeper (up to 50 nm) than the coherence length of the YBCO (≃ 4 nm) by an exchange interaction between the Co magnetic moments and the superconducting pairs at the YBCO/Co interface. The interfacial exchange interaction, switched on while the YBCO enters the SC state, pins Co spins and yields an enhancement of the Co magnetic properties. [ABSTRACT FROM AUTHOR]

VO2 is renowned for its electric transition from an insulating monoclinic (M1) phase, characterized by V–V dimerized structures, to a metallic rutile (R) phase above 340 K. This transition is accompanied by a magnetic change: the M1 phase exhibits a non-magnetic spin-singlet state, while the R phase exhibits a state with local magnetic moments. Simultaneous simulation of the structural, electric, and magnetic properties of this compound is of fundamental importance, but the M1 phase alone has posed a significant challenge to the density functional theory (DFT). In this study, we show none of the commonly used DFT functionals, including those combined with on-site Hubbard U to treat 3d electrons better, can accurately predict the V–V dimer length. The spin-restricted method tends to overestimate the strength of the V–V bonds, resulting in a small V–V bond length. Conversely, the spin-symmetry-breaking method exhibits the opposite trends. Each of these two bond-calculation methods underscores one of the two contentious mechanisms, i.e., Peierls lattice distortion or Mott localization due to electron–electron repulsion, involved in the metal–insulator transition in VO2. To elucidate the challenges encountered in DFT, we also employ an effective Hamiltonian that integrates one-dimensional magnetic sites, thereby revealing the inherent difficulties linked with the DFT computations. [ABSTRACT FROM AUTHOR]

The antiferromagnetic orthoferrite YFeO3 possesses fascinating magnetic properties for spintronics, such as terahertz spin dynamics, ultrafast domain wall motion, and long magnon decay length. YFeO3 belongs to a special family of antiferromagnets that show an unusually strong non-trivial Kerr response due to its weak ferromagnetism. The highly stable antiferromagnetic domains without any spontaneous spin rotation transitions below the 645 K Néel temperature may be useful for nanoscale device applications. We report the successful fabrication of high-quality twinning-free (110)-oriented YFeO3 films by pulsed laser deposition. Detailed structural and magnetic characterization revealed that the crystal structure and magnetic properties of the YFeO3 films are comparable to bulk single crystals. We show that the spin rotation under high magnetic fields follows the two-sublattice approximation model. The film surface is atomically flat with step-terrace surface morphology. A longitudinal magneto-optic Kerr (MOKE) rotation of 10 mdeg was observed at room temperature, which is consistent with earlier reports on bulk single crystals. The in-plane anisotropy of the Kerr response corresponds to the obtained magnetic anisotropy from the SQUID measurement. The large MOKE signal enables the imaging of antiferromagnetic domains and their reversal. The domain size was found to be larger than 100 μm. These high-quality YFeO3 thin films facilitate the fabrication of antiferromagnetic spintronic devices and provide a convenient platform for studying various spin-related phenomena in thin films and at interfaces. [ABSTRACT FROM AUTHOR]

Binary kagome compounds TmXn (T = Mn, Fe, Co; X = Sn, Ge; m:n = 3:1, 3:2, 1:1) have garnered recent interest owing to the presence of both topological band crossings and flatbands arising from the geometry of the metal-site kagome lattice. To exploit these electronic features for potential applications in spintronics, the growth of high-quality heterostructures is required. Here, we report the synthesis of Fe/FeSn and Co/FeSn bilayers on Al2O3 substrates using molecular beam epitaxy to realize heterointerfaces between elemental ferromagnetic metals and antiferromagnetic kagome metals. Structural characterization using high-resolution x-ray diffraction, reflection high-energy electron diffraction, and electron microscopy reveals that the FeSn films are flat and epitaxial. Rutherford backscattering spectroscopy was used to confirm the stoichiometric window where the FeSn phase is stabilized, while transport and magnetometry measurements were conducted to verify metallicity and magnetic ordering in the films. Exchange bias was observed, confirming the presence of antiferromagnetic order in the FeSn layers, paving the way for future studies of magnetism in kagome heterostructures and potential integration of these materials into devices. [ABSTRACT FROM AUTHOR]

The capacity to externally manipulate magnetic properties is highly desired from both fundamental and technological perspectives, particularly in the development of magnetoelectronics and spintronics devices. Here, using first-principles calculations, we have demonstrated the ability of controlling the magnetism of magnetized graphene monolayers by interfacing them with a two-dimensional ferroelectric material. When the 3d transition metal (TM) is adsorbed on the graphene monolayer, its magnetization easy axis can be flipped from in-plane to out-of-plane by the ferroelectric polarization reversal of In2Se3, and the magnetocrystalline anisotropy energy (MAE) can be high to −0.692 meV/atom when adopting the Fe atom at bridge site with downward polarization. This may be a universal method since the 3d TM-adsorbed graphene has a very small MAE, which can be easily manipulated by the ferroelectric polarization. As a result, the inherent mechanism is analyzed by the second variation method. [ABSTRACT FROM AUTHOR]

The capacity to externally manipulate magnetic properties is highly desired from both fundamental and technological perspectives, particularly in the development of magnetoelectronics and spintronics devices. Here, using first-principles calculations, we have demonstrated the ability of controlling the magnetism of magnetized graphene monolayers by interfacing them with a two-dimensional ferroelectric material. When the 3d transition metal (TM) is adsorbed on the graphene monolayer, its magnetization easy axis can be flipped from in-plane to out-of-plane by the ferroelectric polarization reversal of In2Se3, and the magnetocrystalline anisotropy energy (MAE) can be high to −0.692 meV/atom when adopting the Fe atom at bridge site with downward polarization. This may be a universal method since the 3d TM-adsorbed graphene has a very small MAE, which can be easily manipulated by the ferroelectric polarization. As a result, the inherent mechanism is analyzed by the second variation method. [ABSTRACT FROM AUTHOR]

Magnetic refrigeration technology is regarded as one of the ideal solutions for cryogenic refrigeration, while magnetocaloric materials are the crucial ones. A series of polycrystalline RE2Ti2O7 (RE = Gd, Tb, and Ho) compounds were prepared by a simple one-step solid-phase reaction method in the atmosphere. The crystal structure, magnetic properties, and magnetocaloric effect (MCE) of these compounds were systematically investigated. Crystallographic research indicates that these compounds crystallized in a pyrochlore structure. Meanwhile, magnetic measurements illustrate that this class of pyrochlore oxides is highly frustrated magnetic materials and exhibits complex magnetic behavior. In addition, under the field change of 0–1 T, the values of the maximum magnetic entropy change (− Δ S M max ) and the refrigeration capacity are calculated to be 0.9 and 5.8 J/kg for Gd2Ti2O7, 9.0 and 32.9 J/kg for Tb2Ti2O7, 9.9 and 29.9 J/kg for Ho2Ti2O7, respectively. Therefore, RE2Ti2O7 (RE = Tb and Ho) pyrochlores exhibit excellent MCEs under low magnetic fields, providing candidate materials for the application of cryogenic magnetic refrigeration technology. [ABSTRACT FROM AUTHOR]

The realization of remarkable thermoelectric (TE) properties in a novel single-crystalline quantum material is a topic of prime interest in the field of thermoelectricity. It necessitates a proper understanding of transport properties under magnetic field and magnetic properties at low field. We report polarized Raman spectroscopic study, TE properties, and magneto-resistance (MR) along with magnetic characterization of single-crystalline Bi2Se3. Polarized Raman spectrum confirms the strong polarization effect of A 1 g 1 and A 1 g 2 phonon modes, which verifies the anisotropic nature of the Bi2Se3 single crystal. Magnetization measurement along the in-plane direction of single crystal divulges a cusp-like paramagnetic response in susceptibility plot, indicating the presence of topological surface states (TSSs) in the material. In-depth MR studies performed in different configurations also confirm the presence of anisotropy in the single-crystalline Bi2Se3 sample. A sharp rise in MR value near zero magnetic field and low-temperature regime manifests a weak anti-localization (WAL) effect, depicting the quantum origin of the conductivity behavior at low temperature. Moreover, in-plane magneto-conductivity data at low-temperature (up to 5 K) and low-field region (≤15 kOe) confirm the dominance of the WAL effect (due to TSS) with a negligible bulk contribution. Quantum oscillation (SdH) in magneto-transport data also exhibits the signature of TSS. Additionally, an exceptional TE power factor of ∼950 μW m−1 K−2 at 300 K is achieved, which is one of the highest values reported for pristine Bi2Se3. Our findings pave the way for designing single crystals, which give dual advantages of being a good TE material along with a topological insulator bearing potential application. [ABSTRACT FROM AUTHOR]

Magnetic garnet thin films exhibiting perpendicular magnetic anisotropy (PMA) and ultra-low damping have recently been explored for applications in magnonics and spintronics. Here, we present a systematic study of PMA and magnetic damping in bismuth-substituted yttrium iron garnet (Bi-YIG) films grown on sGGG (111) substrates by pulsed laser deposition. Films with thicknesses ranging from 5 to 160 nm are investigated. Structural characterization using x-ray diffraction and reciprocal space mapping demonstrates the pseudomorphic growth of the films. The films exhibit perpendicular magnetic anisotropy up to 160 nm thickness, with the zero-magnetic field state changing from fully saturated for low thicknesses to a dense magnetic stripe pattern for thicker films. The films show a ferromagnetic resonance (FMR) linewidth of 100–200 MHz with a Gilbert damping constant of the order of 4 × 10 − 3 . The broad FMR linewidth is caused by inhomogeneities of magnetic properties on micrometer length scales. [ABSTRACT FROM AUTHOR]

Spherical powders are required for many advanced manufacturing techniques due to their inherent requirement of flowability, either within feed tubes or during powder spreading. As advanced manufacturing of magnets continues to develop, new production methods for feedstocks are also sought. Plasma spheroidization is a high-yield method to produce spherical Nd–Fe–B powders from irregularly shaped particles, with advantages including high throughput and a well-controlled size distribution. Highly spherical Nd–Fe–B powders with large scale production (i.e., kg) have been demonstrated using an inductively coupled thermal plasma system; however, the magnetic properties of the output powder display significant degradation. The coercivity was decreased from the initial 8 kOe (636 kA/m) of the as-received to 0.7 kOe (55 kA/m) for spheroidized powders. Microstructural investigation reveals 6% Nd depletion caused by the extreme temperatures of the plasma, leading to the formation of low-coercivity α-Fe and a subsequent decrease in energy product. Post-spheroidization heat treatments with Nd can partially mitigate the coercivity degradation, increasing to 1.7 kOe (135 kA/m), potentially offering a pathway toward spherical powders for a range of applications. [ABSTRACT FROM AUTHOR]

We study epitaxial growth, crystal structures, and magnetic properties of Fe–As compound thin films grown on GaAs (111)B substrates at various values of the As4:Fe flux ratio γ, using molecular beam epitaxy. The samples grown at low As4 flux (γ = 0.3, sample A) show mainly a body-centered-cubic (bcc) crystal structure, exhibiting ferromagnetic properties similar to bcc Fe. Meanwhile, the Fe–As samples grown at medium γ (2.7–4.5, sample group B) comprise regions of Ni2In-type FeAs (a hexagonal crystal with lattice constants of a = 0.399 nm and c = 0.536 nm), which are grown at the bottom and interface with the GaAs buffer layer, and a layer of non-stoichiometric FeAs with a DO3 structure (a = 0.522 nm) formed on the top. The DO3-structure FeAs phase contains partially transformed regions, which are characterized by thin stripes in a scanning transmission electron microscopy image. Furthermore, in the sample grown with high γ = 8.5 (sample C), a hexagonal Fe–As crystal with a large in-plane lattice constant (a = 0.691 nm and c = 0.542 nm) and threefold screw axes are observed. None of these crystal structures of Fe–As compounds has ever been reported. While sample C shows no ferromagnetism, the samples in group B exhibit strong ferromagnetism with high Curie temperature TC above 400 K. These new ferromagnetic Fe–As compounds are promising for spintronic device applications. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the properties of transition metal (TM)-doped α - G a 2 O 3 using first-principles calculations and Monte Carlo simulations. α - G a 2 O 3 is a wide-bandgap semiconductor material with enhanced performance and lower fabrication costs on sapphire substrates compared to β - G a 2 O 3 . Doping with TMs can modify electrical transport, optical absorption, and magnetic properties, yet theoretical studies on this are scarce. Our study focused on V, Cr, Mn, and Fe impurities. We introduced a newly proposed scheme for efficiently determining the ground-state defect configuration during structural relaxation. We adopt a recent, novel image charge correction method to accurately calculate formation enthalpy and thermodynamic transition levels for spin-polarized transition metal ion doping, without employing the empirical dielectric constant. Results showed Cr ions tend to neutral substitutional Ga, while V, Mn, and Fe impurity ions tend to carry a negative charge in common n-type α - G a 2 O 3 . Magnetic moments and spin-splitting impurity levels primarily arise from transition metal impurities and their d orbitals. We used the generalized four-state method to calculate exchange interaction constants between substitution lattice sites and identified (anti) ferromagnetic couplings at specific distances in a 120-atom supercell, which are negligible in total energy calculations. Monte Carlo simulations indicated a Curie temperature of 360 K in n-type α - G a 2 O 3 : Mn system with 12.5% doping, suggesting intrinsic ferromagnetic ordering based on the Heisenberg model. Our study contributes to understanding TM-doped α - G a 2 O 3 electronic structure and magnetic properties through improved methodologies. The approach can be applied in research involving other TM-doped oxides or wide-bandgap semiconductors. [ABSTRACT FROM AUTHOR]

In truncated coupled-cluster (CC) theories, non-variational and/or generally complex ground-state energies can occur. This is due to the non-Hermitian nature of the similarity transformed Hamiltonian matrix in combination with CC truncation. For chemical problems that deal with real-valued Hamiltonian matrices, complex CC energies rarely occur. However, for complex-valued Hamiltonian matrices, such as those that arise in the presence of strong magnetic fields, complex CC energies can be regularly observed unless certain symmetry conditions are fulfilled. Therefore, in the presence of magnetic fields, it is desirable to pursue CC methods that are guaranteed to give upper-bound, real-valued energies. In this work, we present the first application of unitary CC to chemical systems in a strong magnetic field. This is achieved utilizing the variational quantum eigensolver algorithm applied to the unitary coupled-cluster singles and doubles (UCCSD) method. We benchmark the method on the H2 molecule in a strong magnetic field and then calculate UCCSD energies for the H4 molecule as a function of both geometry and field angle. We show that while standard CCSD can yield generally complex energies that are not an upper-bound to the true energy, UCCSD always results in variational and real-valued energies. We also show that the imaginary components of the CCSD energy are largest in the strongly correlated region. Last, the UCCSD calculations capture a large percentage of the correlation energy. [ABSTRACT FROM AUTHOR]

Intercalation has attracted considerable attention due to its extensive ability to modify the electronic, optical, and magnetic properties of two-dimensional (2D) layered nanomaterials. Typically, dispersed atoms or molecules are inserted into the van der Waals gap of the 2D materials. Recently, Guo et al. experimentally reported the novel VS2–VS superlattice, where the intercalation takes the form of atomic chain arrays. In this study, we employed the first-principles calculations based on density functional theory to investigate a series of analogous 2D MX2–MX–MX2 nanomaterials, which, consisting of 2D transition metal dichalcogenide bilayers, intercalated with a one-dimensional transition metal chalcogenide MX chain array, forming a hotdog-like structure. Some of the 2D MX2–MX–MX2 are thermally and dynamically stable, suggesting their potential for experimental fabrication similar to VS2–VS–VS2. MnS2–MnS–MnS2 and MnSe2–MnSe–MnSe2 have been found to exhibit ferromagnetic half-metallic properties. In addition, VSe2–VSe–VSe2, CrS2–CrS–CrS2, and CrSe2–CrSe–CrSe2 have been found to be thermally and dynamically stable. Under appropriate external stress, doping, or bias, they could become ferromagnetic half-metals, revealing their potential for spintronic applications. [ABSTRACT FROM AUTHOR]

The rare earth alloy Y 2 Co 17 − x Ni x was prepared by a low-cost co-precipitation reduction-diffusion process, and its crystal structure, static magnetic properties, and microscopic morphology were systematically characterized. The effects of Ni doping with different contents on the electromagnetic parameters and wave absorption properties of Y 2 Co 17 − x Ni x /polyurethane(PU) compounds were researched in the frequency range of 0.1–18 GHz. The results show that the static magnetic properties and wave absorption properties change significantly with Ni doping, and the maximum reflection loss of Y 2 Co 14 Ni 3 /PU reaches − 89.7 dB at 2.9 mm thickness, and the maximum reflection loss peaks of Y 2 Co 17 /PU and Y 2 Co 16 Ni 1 /PU are at 1.316 and 1.515 GHz, which is at the center frequency of the L-band. With Ni doping, the effective absorption bandwidth of the compounds at a frequency above 3 GHz is greatly increased. The physical factor in the bandwidth calculation was modified, and the effective absorption bandwidth of the material was calculated theoretically, and the error was less than 5 % compared with the experimental value. [ABSTRACT FROM AUTHOR]

The cobalt-based full Heusler alloy Co2MnGa (CMG) is well known for exhibiting an exotic phenomenon such as magnetic Weyl semimetallic nature with a high Curie temperature of ∼700 K and a giant anomalous Hall effect. Here, we report a detailed study of structural, electrical, and magnetic properties of Co2MnGa thin films (thickness in the 40–10 nm range) grown on Si(100) by the direct-current magnetron co-sputtering technique using Co and MnGa targets. Structural analysis of the samples revealed the polycrystalline nature of these films with B2 type structural ordering. The damping parameter decreases with the increase in film thickness and reaches the minimum value of 6.1 × 10−3 for a 40 nm thin CMG film. These CMG films are magnetically isotropic and soft ferromagnetic in nature. A remarkably high value of anomalous Hall conductivity (AHC) of 1920 S/cm (2 K) is found for the 40 nm thin film, which is comparable to earlier reported values on highly ordered CMG films. Nearly 73% of this AHC value originates from the intrinsic contribution. The AHC and longitudinal conductivity both increase with the film thickness. Different scaling mechanisms are used to compute the intrinsic and extrinsic contributions playing a role in AHC. The analysis of advanced scaling [by Tian et al., Phys. Rev. Lett. 103, 1–4 (2009)] performed on these CMG films suggests the consistency in the enhanced intrinsic AHC value irrespective of the thickness and a decrease in skew scattering contribution with thickness. These results will enhance the understanding about the magnetic and transport properties of Co2MnGa thin films of different thicknesses and suggest it to be a promising material for topospintronic applications. [ABSTRACT FROM AUTHOR]

The largest ever set, RotGT-2023, of statistically validated experimental components of rotational g tensors and respective vibrational corrections, has been created. The experimental values were collected from literature data. The vibrational corrections for obtaining equilibrium molecular g values have been calculated at the highest affordable coupled cluster level of theory. The set comprises 278 parameters from 129 molecules, including their isotopologues. Statistical assessment of the data has been performed to exclude unreliable parameters. A benchmarking of two theoretical approximations, based on coupled cluster and density functional theories, has been performed. The determined weighted mean and weighted standard deviations of the relative errors in calculated equilibrium g values are 1.09% and 2.07% for the ae-CCSD(T)/x2c-TZVPPall-s//ae-CCSD(T)/cc-pwCVTZ level. The obtained results can be used for predicting the rotational Zeeman effect, correcting rotational constants in spectroscopic studies and in molecular structure refinements. The latter has been demonstrated on the refinement of the molecular structure of silane SiH4, which resulted in r e se (Si–H) = 1.473 323 1(27) Å. The other tested theoretical protocol, PBE0/x2c-TZVPPall-s//PBE0-D3BJ/def2-QZVPP, showed considerably worse statistical properties. The RotGT-2023 data set and the developed in this work statistical model are recommended for benchmarking of theoretical approximations for calculations of molecular magnetic properties. [ABSTRACT FROM AUTHOR]

L10-MnAl exhibits excellent magnetic properties and could be used as a candidate to fill the gap between hard ferrite and rare-earth based permanent magnet (PM) applications. However, one of the major problems with L10-MnAl is that the structure is metastable and decomposes to other structural phases at higher temperature. Therefore, enhancing the structure stability of L10-MnAl is essential for PM applications. We studied the prospect of improving the structural stability and increasing the uniaxial magnetic anisotropy energy (K u) of the L10-MnAl structure in this work. It is found that C-doping at the 1d interstitial site enhanced the structure stability of the compound. Moreover, Fe substitution on Mn sites shows a significant increase in the uniaxial magnetic anisotropy energy (K u). Therefore, the electronic structure and magnetic properties of L10-ordered Mn1−xFexAlC (x = 0, 0.125, 0.250, 0.375, 0.50, 0.625, 0.75, and 0.87) alloys are investigated by using the first-principles calculations. The results show that x = 0.375 Fe content in the L10-MnAl alloy and 6% doping of C maintained the structural stability and provided a maximum value of K u = 2.13 (MJ/m3), which is 25% higher than for the pristine L10-MnAl, making it suitable for permanent magnet applications. [ABSTRACT FROM AUTHOR]

We report on the thermal and magnetic properties of D y 1 − x S c x N i 2 series compounds (x = 0.1 , 0.3 , 0.5 , and 0.7), which were investigated through a model Hamiltonian including the exchange, Zeeman, and crystalline electric field interactions. We investigated the effect of Sc substitution on the Dy site on the magnetic and magnetocaloric properties of these compounds. Theoretical results were simulated for heat capacity, entropy, and the magnetocaloric effect quantities. Our model reproduced the decrease of the magnetic ordering temperature and of the isothermal entropy change peaks as Sc concentration increases. Our theoretical results were confronted with experimental data from the literature, showing good agreement. [ABSTRACT FROM AUTHOR]

Giant magnetostrictive material (GMM) is well known for its hysteresis behaviors related to multiple influencing factors, such as bias magnetic field and excitation level. This feature greatly challenges the loss prediction of giant magnetostrictive transducers. The existing loss prediction models need further improvement to cover the sensitive magnetic properties of GMM. In this paper, the variations of the iron losses with the operation conditions are interpreted by the variations of the Jiles–Atherton model parameters, and a concise parameter identification procedure with great generalizability is proposed. The iron losses of Terfenol-D under variable excitation levels and the DC biases are further investigated. With the proposed procedure, the introduced eight additional modification parameters for the original Jiles–Atherton model are easy to obtain, and merely a few hysteresis loops of Terfenol-D are involved. An experimental setup is established for further demonstration. Comparisons between the measured and calculated results indicate the effectiveness of the proposed approach. Throughout the bias-excitation space within the frequency range under investigation, the iron losses can be precisely estimated with an acceptable error of less than 5%. [ABSTRACT FROM AUTHOR]

Magnetocaloric properties of TbCrO3 and TmCrO3 are reported and compared with those of the previously reported rare-earth chromites RCrO3 (R = Gd, Dy, Ho, and Er) and other perovskite-type oxides. The samples of TbCrO3 and TmCrO3 in this work were synthesized using a citrate gel combustion technique, and their magnetic properties were investigated and compared with those reported previously on RCrO3 (R = Gd, Dy, Ho, and Er). The Cr3+–Cr3+ ordering temperatures were found to strongly depend on the ionic radii of the rare-earth. By fitting the dc magnetization data with modified Curie–Weiss law including the Dzyaloshinsky–Moriya antisymmetric exchange interaction (D) and the symmetric exchange constant Je, spin canting angles (α) were obtained. In general, α was found to increase with the decreasing ionic radii of R3+ in RCrO3. The magnetocaloric properties investigated included the magnetic entropy change (−ΔS) for a given change in magnetic field (ΔH), the corresponding adiabatic temperature change (ΔTad), and their relative variations (ΔTad/ΔH) and (−ΔS/ΔH). It is observed that for RCrO3, (−ΔS) measured in the vicinity of the ordering temperature of R3+–R3+, varies almost as G2/3 where G is the de Gennes factor. Among RCrO3, GdCrO3 shows the largest value of (−ΔS/ΔH), because of its largest G factor and its magnitudes of (ΔTad/ΔH) and (−ΔS/ΔH) compare well with the reported values for the perovskites GdFeO3 and EuTiO3. These comparisons presented here provide useful information on the potential use of these materials in magneto-refrigeration technology. [ABSTRACT FROM AUTHOR]

We report a large cryogenic magnetocaloric effect stemming from an unconventional borderline first-order magnetic phase transition with negligibly small thermomagnetic hysteresis in a rare-earth-based intermetallic compound PrNdIn. The sample exhibits maximum magnetic field-induced entropy change as large as −10 J/Kg K (for 20 kOe magnetic field change) near the boiling point of oxygen. Magnetocaloric properties of PrNdIn are comparable to those of other known potential magnetocaloric materials with operating temperatures ranging between 50 and 125 K. The magnetic properties of the present sample are qualitatively reminiscent of those of the binary Pr2In and Nd2In, including the emergence of a second low-temperature anomaly in the temperature dependence of magnetization. [ABSTRACT FROM AUTHOR]

Investigating high-performance and stable spintronics devices has been a research hotspot in recent years. In this paper, we employed first-principles methods and Monte Carlo (MC) simulations to explore the structure, electronic, and magnetic properties of monolayer NbSe2, as well as its behavior under carrier concentration modulation. The research on the electronic structure reveals that by introducing an appropriate amount of holes, the material can undergo a transition from metal to a half-metal state, achieving 100% high spin polarization. Investigation of magnetic crystalline anisotropy shows that the magnetic crystal anisotropy energy of 1210 μeV in out-of-plane is beneficial to maintain ferromagnetic order at high temperatures. In addition, doping with suitable carriers can effectively enhance or strengthen the ferromagnetic coupling in NbSe2 so that the magnetization easy axis is shifted. This reveals the potential application prospects of NbSe2 in electronically controlled spintronic devices. Analysis of the Fermi surface shows that both holes and electron doping increase the Fermi velocity of the material. The effect of hole doping is particularly significant, indicating its potential application in Fermi velocity engineering. Under the theoretical framework of the extended two-dimensional Ising model, based on MC simulation, the Curie temperature (TC) of NbSe2 is predicted to be 162 K. The effects of carrier concentration and the magnetic field on the magnetic and thermal properties of monolayer NbSe2 are simulated. The results show that appropriately increasing the hole doping concentration and magnetic field is conducive to obtaining ferromagnetic half-metallic materials with TC higher than room temperature, which provides theoretical support for experimental preparation. [ABSTRACT FROM AUTHOR]

The concept of building logically functional networks employing spintronics or magnetic heterostructures is becoming more and more popular today. Incorporating logical segments into a circuit needs physical bonds between the magnetic molecules or clusters involved. In this framework, we systematically study ultrafast laser-induced spin-manipulation scenarios on a closed system of three carbon chains to which three Ni atoms are attached. After the inclusion of spin–orbit coupling and an external magnetic field, different ultrafast spin dynamics scenarios involving spin-flip and long-distance spin-transfer processes are achieved by various appropriately well-tailored time-resolved laser pulses within subpicosecond timescales. We additionally study the various effects of an external magnetic field on spin-flip and spin-transfer processes. Moreover, we obtain spin-dynamics processes induced by a double laser pulse, rather than a single one. We suggest enhancing the spatial addressability of spin-flip and spin-transfer processes. The findings presented in this article will improve our knowledge of the magnetic properties of carbon-based magnetic molecular structures. They also support the relevant experimental realization of spin dynamics and their potential applications in future molecular spintronics devices. [ABSTRACT FROM AUTHOR]

Chiral molecules have the potential for creating new magnetic devices by locally manipulating the magnetic properties of metallic surfaces. When chiral polypeptides chemisorb onto ferromagnets, they can induce magnetization locally by spin exchange interactions. However, direct imaging of surface magnetization changes induced by chiral molecules was not previously realized. Here, we use magneto-optical Kerr microscopy to image domains in thin films and show that chiral polypeptides strongly pin domains, increasing the coercive field locally. In our study, we also observe a rotation of the easy magnetic axis toward the out-of-plane, depending on the sample's domain size and the adsorption area. These findings show the potential of chiral molecules to control and manipulate magnetization and open new avenues for future research on the relationship between chirality and magnetization. [ABSTRACT FROM AUTHOR]

The topological antiferromagnet γ -FeMn is a fascinating material for studying unconventional magnetic properties and topological transport phenomena though high-quality γ -FeMn has been obtained on the Cu substrate for magnetic research. However, the difficulty of growing single-crystalline γ -FeMn films on insulating substrates has prevented experiments from exactly verifying many theoretical predictions on their transport properties. Ultrathin Cu buffer films have been considered for solving this problem but failed because the crystal quality and thickness of Cu films achieved in previous works do not satisfy the growth buffer criteria for γ -FeMn. In this work, the growth of 5-nm-thick Cu films on SrTiO 3 (001) substrates was studied. It was found that single-crystalline ultrathin Cu films with roughness as low as 1 nm are obtained on the insulating substrate. We subsequently obtained high crystalline quality γ -FeMn films with smooth surface and verified their antiferromagnetism. Finally, two aspects of the influence of Cu films on adjacent films have been analyzed. Our results facilitate the experimental exploration of the fascinating properties of γ -FeMn. [ABSTRACT FROM AUTHOR]

The present study is focused on the investigation at 400 K of the tetragonal-rutile phase of Cr-doped VO2 (CVO) thin films grown by pulsed laser deposition. Synchrotron-based x-ray measurements of both the surface-sensitive total electron yield (TEY) and bulk-sensitive total fluorescence yield (TFY) modes were used to investigate the pristine and Cr-doped VO2 (5%, 10%, 20%, and 30% of atomic weight). The structural analysis and purity of the crystalline phase of the as-deposited films are manifested via grazing incidence x-ray diffraction patterns, which confirm the tetragonal-rutile phase. The purity of the phase is also confirmed by the presence of Eg-mode phonons in the Raman spectra and its deconvolution reflects on the oxygen-mediated electronic/vibrational transitional effect. A clear hysteretic behavior obtained through vibrating sample magnetometry strongly suggests the ferromagnetic interaction in the thin films of CVO. The local-electronic property of the samples is examined using x-ray absorption spectroscopy (XAS) in TEY and TFY modes where the difference in the configured helicity photons resulted in the fine spectra of x-ray magnetic circular dichroism (XMCD). XAS and XMCD measurements performed at V L2,3 and Cr L2,3 edges explicitly demonstrate the ferromagnetism in the thin films of CVO. The strong hybridization between V 3d and Cr 3d states with O 2p states is evident from the spectra of the O K-edge, resulting in the onset of the cation-pair formation V5+–Cr3+, which is ferromagnetic by means of double-exchange interaction. The theoretical calculation of density functional theory made upon Vienna ab initio simulation package suggests that CVO is in a mixed state of a ferromagnetic-insulator and a half-metallic ferromagnet. [ABSTRACT FROM AUTHOR]