Search

We systematically investigate the crystal structure, magnetic properties and magnetocaloric effect (MCE) of antipervoskite compound Zn0.6NFe3.4. There is a ferromagnetic to paramagnetic second-order phase transition to the Curie temperature (TC ~ 140 K), and the saturation magnetization (MS ~ 116.97 emu/g) is expressed at 5 K. The non-hysteresis behavior of the sample's M(H) curves are of great significance of the research and application of its magnetic refrigeration. Therefore, the study of its MCE has obtained the maximum magnetic entropy change ( - Δ S M max ~ 2.21 J/kg K) and the relatively high relative cooling power (~ 207.69 J/kg for ΔH = 50 kOe) around TC. Moreover, due to the advantages of easy preparation, low cost and non-toxic, Zn0.6NFe3.4 can become a magnetic refrigeration material with great application potential. Our research also provides a reference from the study of the MCE of other antiperovskite structure compounds. [ABSTRACT FROM AUTHOR]

Through the magnetic/thermal transport measurements combined with the analyses of magnetocaloric effect and critical behavior of Co3Sn2S2 single crystal, the main results we obtained are as follows: in the case of the magnetic field H//c‐axis, Co3Sn2S2 exhibits the phase‐separation state below Tc in the low‐field region (H < 500 Oe). Tc increases slightly from 174 to 177 K with an increase in H from 100 to 10 kOe. The second‐order magnetic phase transition near Tc and the itinerant ferromagnetism below Tc are identified. The magnetization below Tc matches well with the three‐dimensional Ising model, instead of the mean‐field model. In the case of H//ab, Tc changes between 175 and 178 K with varying H. Noticeably, M above Tc exhibits a small positive value, instead of the null M as commonly expected in the paramagnetic region. An extra phase transition below 166 K is observed. The magnetic transition near Tc seems not to be the second‐order phase transition. All results show a significant characteristic of anisotropic magnetic phase transition for the Co3Sn2S2 single crystal. They support mutually those in previous reports, moreover, some new phenomena are also observed. They also provide the experimental evidences for the deep insight into the magnetic phase–transition behavior of Co3Sn2S2. [ABSTRACT FROM AUTHOR]

In this study, the critical behavior of the Fe-based carbide antiperovskite compound AlC1.1Fe3 has been presented. There is a second-order phase transition and the magnetic state will change from ferromagnetic state to paramagnetic state near Curie temperature. Critical exponents (β, γ, δ) representing different significance of magnetism are obtained by separate classical methods, which are exceedingly agreeable with the mean-field model theory, indicating that magnetic behavior of AlC1.1Fe3 is dominated by long-range ferromagnetic coupling. According to the scaling equation m = f ± (h), the experimental data obtained by the two experimental methods roughly overlap on the two curves, which demonstrates the reliability of these fitting parameters, and the convergence of the parameters also conforms to the mean-field model. Besides, the mutual exchange distance J(r) decreases as r−4.695 due to the competitive Fe–Fe metal bond and Fe–C covalent bond. We suggest that the competition between the localized metal bond magnetic interaction and itinerant covalent bond hybridization should be responsible for the critical behavior of AlC1.1Fe3. [ABSTRACT FROM AUTHOR]

Broadband photodetectors with polarization-sensitive ability have received extraordinary attention for modern optoelectronic devices. Ideal photodetectors should possess high responsivity, fast response, and good stability, which are rare to meet at the same time in one low-symmetric two-dimentional (2D) material. In this work, neodymium diantimonides (NdSb2), a member of light rare-earth diantimonides RSb2 (R = La−Nd, Sm) with low-symmetry structure, is introduced as a fascinating highly anisotropic 2D material for broadband detection (532 nm to 4 µm). The photodetector exhibits a responsivity of 0.49 mA·W−1 with 15 µs response time at 532 nm and highly stable performance under ambient conditions over 8 months. Furthermore, we identify the polarization-sensitive photoresponse of the detector and demonstrate a high anisotropic factor ∼ 1.6. In addition, strong in-plane anisotropy is revealed by anisotropic phonon response and the photodetection mechanism is investigated by scanning photocurrent microscopy measurements. This pioneer work on NdSb2 paves the way for further exploration of 2D RSb2 for high performance polarized photodetectors with fast photothermoelectric response. [ABSTRACT FROM AUTHOR]

A series of Zn-substituted CoCr2O4 spinel powders were prepared by solid-state reaction method. On this basis, the crystal structure and magnetic properties of CoCr2O4 powders were studied. By comparing the X-ray diffraction (XRD) pattern with the CoCr2O4 spinel standard card, it can be seen that the position of the main peak changes with the increase of zinc content and moves to the direction of higher Angle. In other words, with the increase of Zn displacement, the average grain size and lattice parameters also change. The crystal structure and magnetic properties of the materials were studied using the following instruments: scanning electron microscope (SEM) image can clearly see the uniform grain distribution. The chemical valence states of zinc, cobalt, and chromium ions fitted by X-ray photoelectron spectroscopy (XPS) are consistent with those reported in previous literature. The formation of spinel chromite can be clearly seen in the Fourier transformer infrared (FTIR) image. The hysteresis loop at 5 K shows that the saturation magnetization and coercivity decrease with the increase of Zn2+ content. At room temperature (300 K), the hysteresis loops of the five samples are linear. When x = 0.1 and 0.3, ZFC curve shows negative magnetization behavior across the temperature axis. The paramagnetic behavior also confirmed the pure spinel phase shown in the powder XRD profile. [ABSTRACT FROM AUTHOR]

Spin-glass (SG) behavior is observed in the binary nitride ε-Fe2N, which is confirmed through a series of magnetic measurements (Temperature-dependent magnetization M(T), isothermal hysteresis loop M(H), DC magnetization, AC susceptibility, and magnetic relaxation measurements). The strong irreversibility is evidently observed from the curves of zero-field-cooling and field-cooling. The corresponding specific parameters are obtained: the flipping time τ 0 = 1.422 × 10–11 s, the freezing temperature T0 = 9.09 K, and the dynamical exponent zv = 7.183. The typical relaxation behavior of isothermal remanent magnetization (MIRM) shows strong spin frustration in ε-Fe2N. Besides, the electron spin resonance (ESR) measurements distinctly indicate that the coexistence of ferromagnetic (FM) and anti-ferromagnetic (AFM) in the system, which may be the cause of the SG behavior in ε-Fe2N. [ABSTRACT FROM AUTHOR]

The single phase of the spinel ferrite MgGaFeO4 is successfully prepared by the high‐temperature solid‐state reaction. The crystal structure, cation distribution, valence state, and magnetic properties are systematically investigated through various techniques in this work. From the analysis of X‐ray diffraction, the face‐centered cubic structure with the space group Fd3m for the single‐phase sample is obtained. The magnetic hysteresis loops M(H) shows a typical magnetic hysteresis behavior at 5 K, while an obvious paramagnetic behavior can be observed at room temperature. The characteristics of magnetic properties suggest that the intrinsic ferromagnetic (FM) interaction and magnetic frustration are cooperated in the system. The specific divergence and irreversibility in the temperature‐dependent magnetization curves M(T) indicate a typical spin‐glass (SG) behavior, which occurring around the freezing temperature Tf = 40 K. Further analysis of the isothermal remanent magnetization (MIRM) suggests the existence of an intensive magnetic frustration state, which leads to stable residual magnetization without decaying under a long time span. More than that, based on the corresponding fitting parameters (τ0 = 8 × 10−12 s, zv = 6.32 and T0 = 56.2 K), the SG state in the sample is further confirmed. The following detailed analyses reveal that the competitions between antiferromagnetic (AFM) and ferromagnetic (FM) interactions definitely exist in MgGaFeO4, which should be the response to motivate the SG behavior. [ABSTRACT FROM AUTHOR]

Polarized photodetectors have been widely used in military and civilian applications. The investigation of promising two-dimensional materials with low symmetry structures will be of great significance for the development of polarized integrated nanodevices. In this work, chromium thiophosphate (CrPS4), a ternary layered semiconductor with low symmetry puckered structures and unique linear dichroism (LD) conversion behavior is introduced to act as a polarization-sensitive photodetector. Angle-resolved polarized Raman spectra (ARPRS), polarization-resolved photoluminescence (PL) spectra, polarization-resolved absorption spectroscopy (PRAS), and electrical transport measurement systematically indicate intriguing anisotropic optical and electrical properties in 2D (two-dimensional) CrPS4. The photodetector of CrPS4 shows a linear anisotropy ratio of ≈1.33 with 405 nm illumination. This pioneering research not only stimulates interest in the development of novel anisotropic 2D materials but also enriches the family of polarization-sensitive photodetectors. [ABSTRACT FROM AUTHOR]

All samples of CoGa2-xFexO4 (x = 0.0, 0.4, 0.8, 1.2, 1.6) systematically synthesized using a traditional ceramic technology in the present work. Phase purity, crystal structure, valence state distribution, ion occupancy rate, and magnetic properties of the prepared samples are systematically investigated with X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometer measurements. The experimental results exhibited that the Curie temperature (Tc), intrinsic coercivity (Hc), saturation magnetization (Ms), real permeability (µ′), and core loss Pcv performance of Fe ion-doped CoGa2O4 were optimized at the appropriate doping content. Compared with x = 0, the doped sample obtained the relatively high Ms = 85 emu/g and lower Hc is 180 Oe in x = 1.2. Besides, a higher Curie temperature (Tc), a higher real permeability (µ′) value, and a relatively low Pcv value were obtained. Comprehensive experimental results show that the sample possesses a wider range of application under the doping levels of x = 1.2. [ABSTRACT FROM AUTHOR]

We report the Griffiths phase (GP) and transport behavior in the quaternary antiperovskite nitrides Ge1−xSnxNFe3 by a series of systematical magnetic susceptibility and thermoelectric behavior measurements. All the corresponding fitting exponent parameters λGP = 0.852 and 0.854 completely satisfy 0 ≤ λ ≤ 1 in GP regions for Ge0.7Sn0.3NFe3 and Ge0.8Sn0.2NFe3, respectively, indicating the different ferromagnetic concentrations in the system. An observed structural transition from distorted tetragonal structure (I4/mcm) to cubic antiperovskite (Pm3m) with increasing dopants should be responsible for the GP in Ge1−xSnxNFe3, which results in a magnetic phase transition from ferromagnetism (FM) to antiferromagnetism (AFM). Furthermore, the studies of electrical transport properties indicate that the Ge1−xSnxNFe3 series of compounds perform a Fermi liquid behavior at low temperature while the stronger electron‐phonon scatterings are found in the high‐temperature region. In addition, the intensive electron–electron correlation is also determined since much higher value of lattice thermal conductivity κl than the one of electronic thermal conductivity κe. [ABSTRACT FROM AUTHOR]

We report the Griffiths phase (GP) and transport behavior in the quaternary antiperovskite nitrides Ge1−xSnxNFe3 by a series of systematical magnetic susceptibility and thermoelectric behavior measurements. All the corresponding fitting exponent parameters λGP = 0.852 and 0.854 completely satisfy 0 ≤ λ ≤ 1 in GP regions for Ge0.7Sn0.3NFe3 and Ge0.8Sn0.2NFe3, respectively, indicating the different ferromagnetic concentrations in the system. An observed structural transition from distorted tetragonal structure (I4/mcm) to cubic antiperovskite (Pm3m) with increasing dopants should be responsible for the GP in Ge1−xSnxNFe3, which results in a magnetic phase transition from ferromagnetism (FM) to antiferromagnetism (AFM). Furthermore, the studies of electrical transport properties indicate that the Ge1−xSnxNFe3 series of compounds perform a Fermi liquid behavior at low temperature while the stronger electron‐phonon scatterings are found in the high‐temperature region. In addition, the intensive electron–electron correlation is also determined since much higher value of lattice thermal conductivity κl than the one of electronic thermal conductivity κe. [ABSTRACT FROM AUTHOR]

Polycrystalline La0.7Sr0.3MnO3 sample (LSMO) was synthesized by the solid phase reaction; it exhibits the paramagnetic‐ferromagnetic transition at Tc = 362 K at the ambient pressure; it is paramagnetic metallic state above Tc and the ferromagnetic metallic state below Tc. It was observed that the pressure effect depends on the temperature range: (a) In the paramagnetic region, the magnetization M hardly changes with the pressure P, that is, ΔM≈0. There exist the antiferromagnetic (AFM) coupled ferromagnetic clusters in the paramagnetic region, and the pressure enhances the AFM coupling. (b) In the temperature range around Tc, the pressure increases M, that is, ΔM > 0, with the concomitant increase in Tc; the average pressure coefficient dTc/dP is 5.40 K/GPa at P =.74 GPa, much smaller than 15.47 and 15.90 K/GPa for La0.7Ca0.3MnO3 and La0.9Ca0.1MnO3, respectively, due to the different distortion degree of MnO6 octahedra in Ca and Sr doped manganites. (c) In the temperature region below Tc, the pressure reduces M, that is, ΔM < 0. M is determined by the competition between the Mn3+‐O‐Mn4+ double exchange and the interparticle dipolar interaction. The pressure enhances the interparticle dipolar interaction, leading to a significant decrease in magnetization. The resistivity of LSMO exhibits the metallic behavior in the temperature range of 5 K~370 K; it decreases as the applied magnetic field H increases from 0 to 7 T, that is, the magnetoresistance effect which is more significant around Tc. The fitting to the low‐temperature resistivity shows that the applied magnetic field reduces the scattering from the grain boundary, electron, phonon, and magnon, especially reduces the electron‐electron scattering. [ABSTRACT FROM AUTHOR]

In this paper, we report a spin-glass (SG) behavior by comprehensive magnetic measurements in spinel compound ZnCoTiO4. The temperature dependence of DC magnetization exhibits a strong irreversibility under zero field cooled and field cooled processes. At the same time, AC susceptibility measurement reveals that the peak position moves towards high temperature with increasing frequency. These results unanimously indicate that a magnetic frustration behavior has occurred in this system. In addition, the relevant parameters (T0 = 14.4 K, τ0 = 8.3165 × 10−11 s, zν = 4.53) are observed by the data of AC susceptibility measurement, suggesting a typical SG behavior. The magnetic relaxation behavior (MIRM vs. t) further manifests a SG behavior in ZnCoTiO4. Furthermore, the origin of SG behavior in ZnCoTiO4 may be contributed to atomic disorders or the competition between ferromagnetic (FM) and antiferromagnetic (AFM) interactions, or both. [ABSTRACT FROM AUTHOR]

In this paper, we report a spin-glass (SG) behavior by comprehensive magnetic measurements in spinel compound ZnCoTiO4. The temperature dependence of DC magnetization exhibits a strong irreversibility under zero field cooled and field cooled processes. At the same time, AC susceptibility measurement reveals that the peak position moves towards high temperature with increasing frequency. These results unanimously indicate that a magnetic frustration behavior has occurred in this system. In addition, the relevant parameters (T0 = 14.4 K, τ0 = 8.3165 × 10−11 s, zν = 4.53) are observed by the data of AC susceptibility measurement, suggesting a typical SG behavior. The magnetic relaxation behavior (MIRM vs. t) further manifests a SG behavior in ZnCoTiO4. Furthermore, the origin of SG behavior in ZnCoTiO4 may be contributed to atomic disorders or the competition between ferromagnetic (FM) and antiferromagnetic (AFM) interactions, or both. [ABSTRACT FROM AUTHOR]

We report studies of the complex magnetic ordering, pressure-induced magnetic properties, large exchange bias (EB), spin-glass (SG), critical behavior, and electron spin resonance (ESR) in spinel Co2TiO4. The magnetic compensation behavior occurs in the vicinity of the compensation temperature Tcomp ∼ 32.5 K (defined as the susceptibility χZFC = χFC = 0), which can be attributed to the behavior that the magnetization of two bulk sublattices balances each other completely. The nature of this unusual case is demonstrated by the spin direction upon applied field and A–B sublattice (site) coupling. Specifically, the values of exchange integrals JAA and JBB play a crucial role at lower and higher temperatures, respectively. It is prominent that intrinsic coercivity Hcj increases by 168% at a pressure of 1000 MPa, from which we illustrate the antiferromagnetic (AFM) transition based on magnetic hysteresis loops M(H) and temperature dependent magnetization M(T) curves. The SG behavior of Co2TiO4 is confirmed by a series of reliable measurements and fitting parameters (τ0, zv), and a large EB field is also found through the asymmetry in the M(H) curve. Besides, the critical behavior of Co2TiO4 is studied initially in our present work, and the critical exponents (β, γ, and δ) indicate long-range ferromagnetic (FM) coupling accompanied by a short-range interaction in Co2TiO4. [ABSTRACT FROM AUTHOR]

The crystal structure, electromagnetic properties and magnetocaloric effect (MCE) of ternary iron-based ZnFe3N nitride have been investigated systematically. The density of states (DOS) calculation combined with theoretical model analysis suggests that ZnFe3N has a second-order ferromagnetic phase transition process existing in the cubic system. Its saturation magnetization (Ms) is about 108.3 emu/g at 5 K. The maximum values of magnetic entropy change (|ΔSM| = 2.2984 J/kg K) and relative cooling power (RCP = 247.0671 J/kg) are calculated from the measurements at a magnetic field change ΔH = 50 kOe, respectively. [ABSTRACT FROM AUTHOR]

The spin glass (SG) behavior of Ni substituted spinel ferrites having chemical formula Zn 0.8- x Ni x Cu 0.2 Fe 2 O 4 (0 ≤ x ≤ 0.28) has been systematically investigated. By means of zero-field-cooling and field-cooling magnetizations, the strong irreversibility is distinct demonstrated. The measurement results demonstrate a typical SG behavior for 0 ≤ x ≤ 0.28. Antiferromagnetic (AFM) interaction is dominant in the competition between ferromagnetic (FM) and AFM interaction for x = 0. In addition, the freezing temperature of the SG state exhibits a decrease with increasing pressure since the SG state is inhibited. As the substitution of Ni for Zn increase, the interaction of FM gradually is equivalent to the AFM interaction and dominant, while the M S and T C increase which is due to the enhancement of the super-exchange interaction J AB. [ABSTRACT FROM AUTHOR]

A EuZnSb2 antiferromagnetic (AFM) semi metal with a P4/nmm space group (No. 129) is synthesized using the Sb-flux method. The magnetic properties, specific heat, and resistivity of the EuZnSb2 single crystals are analyzed. The magnetic and specific heat properties indicate an antiferromagnetic order of Eu2+ with TN ~ 20 K. The magnetic field is observed to suppress the AFM transition of Eu2+ and the magnetic susceptibility vs. temperature curves exhibit differences when the magnetic field is applied along the ab-plane and c-axis of EuZnSb2 single crystal, reflecting a weak in-plane anisotropy of Eu2+. When the temperature is below 20 K, a spin‒flop transition of the AFM order appears at approximately 1.6 T. The electronic transport measurements indicate that a EuZnSb2 single crystal exhibits metallic properties and an extremely unsaturated positive MR effect. A twofold period of anisotropic magnetoresistance is observed, indicating that the resistivity characteristics correlate with the magnetic field intensity and the angle between the magnetic field direction and the crystallographic axis direction. These studies contribute to enriching the magnetic, specific thermal, and electrical transport properties of EuZnSb2. These results also provide valuable information for further research on other AFM materials. [ABSTRACT FROM AUTHOR]

For soft magnetic materials, especially new intermetallic compounds, some good soft magnetic properties, such as high permeability, low power loss, as well as superior DC-bias properties, will determine their prospects for application. In this paper, we report soft magnetic properties of CuxNFe4−x, prepared by a new synthetic method. Although the saturation magnetization of the samples is slightly lower than that of Fe4N due to Cu doping, various other experimental results clearly provide evidence that the Fe substitution by Cu leads to the optimization and improvement of soft magnetic properties in Fe4N. With increasing Cu content, the permeability increases and power loss reduces from 1064.5 mW/cm3 for x = 0.1 to 679 mW/cm3 for x = 0.5 at H = 8 A/m, f = 1000 kHz. Additionally, the value of DC-bias (μH/μH=0) rises above 82% at H = 100 Oe, implying a superior DC-bias properties. More importantly, with the increases of x content, the value of μH/μH=0 increases and reaches 87% for sample x = 0.5 at H = 100 Oe. The improvement of soft magnetic properties of the Fe-based antiperovskite CuxNFe4−x is encouraging for future applications as functional materials. [ABSTRACT FROM AUTHOR]

W-type ferrite Sr1−xLaxFe22+Fe163+O27 (x = 0.00, 0.05, 0.08, 0.10, 0.13 and 0.15) powders and magnets were prepared via the solid-state reaction in nitrogen. Phase components of the powder samples were examined by X-ray diffraction (XRD). XRD results demonstrated the appearance of pure phase hexagonal crystal structure and calculate the lattice constants c and a, c/a ratio, cell volume (Vcell), X-ray density (dX-ray) and crystallite size (D) parameters according to XRD data. Scanning electron microscopy (SEM) was used to observe the morphology of the magnets. SEM analyses revealed the hexagonal morphology of the ferrites. The magnetic characteristics of magnetic powders were measured by a vibrating sample magnetometer (VSM), and the magnetic characteristics of magnets were also measured by a permanent magnetic measuring equipment. The results indicate that, the synthesized samples with a low coercive force value and a considerable saturation magnetization are best able to make optical read-out of the magnetic storage information in erasable video and audio discs. [ABSTRACT FROM AUTHOR]

In this paper, the effect of adding Permalloy (< 15 µm) on Fe83.5Si7.5B5Cr4 amorphous nanocrystalline magnetic powder (< 50 µm) was studied. The best stress relief annealing temperature were revealed at the same time. The results showed that the addition of Permalloy will significantly affect the soft magnetic properties of Fe-based amorphous nanocrystalline powders. Compared to the Fe83.5Si7.5B5Cr4 amorphous nanocrystalline powder, the saturation magnetization of composite powders obviously increased (by 9.8-17.1%). When Permalloy content was 15 wt%, the sample had the highest effective permeability, which increased by 21.6% (f = 200 kHz). At the same time, the core loss was also reduced by 5.3% (Bm = 40 mT, f = 200 kHz) when Permalloy content was 10 wt.%. In addition, the magnetic powder core had the highest effective permeability and the lowest core loss when the stress relief annealing temperature was set to 773 K. [ABSTRACT FROM AUTHOR]

The Pr, Cu, and Pr75Cu25 were deposited on the sintered NdFeB by magnetron sputtering technology, and the samples were subjected to grain boundary diffusion heat treatment. The magnetic properties, microstructure, temperature stability and bending strength of the magnet were analyzed. Compared with the blank magnet, the grain boundaries of the diffusion magnet increase and enhance the Nd phase and its continuum, thereby isolating the main phase grains and resulting in a stronger magnetic decoupling effect. The coercivity of Pr and Pr75Cu25 diffusion magnets increased from 12.86 kOe to 14.69 kOe and 15.78 kOe, respectively, while the coercivity of diffusion Cu magnets increased from 13.38 kOe to 14.83 kOe. In the temperature range of 20 ~ 120 °C, the reversible temperature coefficients of coercivity (|β|) of diffusion Pr, Cu, and Pr75Cu25 magnets decrease by 0.034%/°C, 0.021%/°C and 0.089%/°C, respectively. Meanwhile, the irreversible flux magnetic loss (Hirr) decreased by 20.96%, 0.94%, and 27.71% respectively. The average bending strength increased by 55.89 MPa, 155.65 MPa, and 130.21 MPa, respectively. [ABSTRACT FROM AUTHOR]