Magnetic Hysteresis Behavior Research Articles

Automated setup for magnetic hysteresis characterization based on a voltage controlled current source with 500 kHz full power bandwidth and 10 A peak-to-peak current.

This paper describes the design of a system for the characterization of magnetic hysteresis behavior in soft ferrite magnetic cores. The proposed setup can test magnetic materials exciting them with controlled arbitrary magnetic field waveforms, including the capability of providing a DC bias, in a frequency bandwidth up to 500 kHz, with voltages up to 32 V peak-to-peak, and currents up to 10 A peak-to-peak. In order to have an accurate control of the magnetic field waveform, the system is based on a voltage controlled current source. The electronic design is described focusing on closed loop feedback stabilization and passive components choice. The system has real-time hysteretic loop acquisition and visualization. The comparisons between measured hysteresis loops of sample magnetic materials and datasheet available ones are shown. Results showing frequency and thermal behavior of the hysteresis of a test sample prove the system capabilities. Moreover, the B-H loops obtained with a multiple waveforms excitation signal, including DC bias, are reported. The proposal is a low-cost and replicable solution for hysteresis characterization of magnetic materials used in power electronics.

Reentrant spin glass ordering in an Fe-based bulk metallic glass

We report the results of the complex susceptibility, temperature, and field dependence of DC magnetization and the nonequilibrium dynamics of a bulk metallic glass Fe40Co8Cr15Mo14C15B6Er2. Solid indication of the coexistence of reentrant spin glass (SG) and ferromagnetic orderings is determined from both DC magnetization and AC susceptibility under different DC fields. Dynamics scaling of AC susceptibility indicates critical slowing down to a reentrant SG state with a static transition temperature Ts = ∼17.8 K and a dynamic exponent zv = ∼7.3. The SG nature is further corroborated from chaos and memory effects, magnetic hysteresis, and aging behavior. We discuss the results in terms of the competition among random magnetic anisotropy and exchange interactions and compare them with simulation predictions.

Magnetic hysteresis and compensation behaviors in spin-1 bilayer Ising model

The hysteresis and compensation behaviors of spin-1 bilayer Ising model on a square lattice is studied within the framework of the effective-field theory with correlation. The effects of Hamiltonian parameters on hysteresis behaviors are discussed in detail. We also obtained the Q-, R-, P-, S- and L-type compensation behaviors in the system. A number of interesting phenomena such as the shape of the hysteresis loops and compensation types have been found. The obtained results are compared with some experimental and theoretical results and found to be in a qualitatively good agreement.

Structural development and magnetic phenomenon in Zn–Cr–Fe multi oxide nano-crystals

The Cr3+ ions doped multi-oxide ZnFe2−xCrxO4 ferrite nanoparticles have been synthesized by chemical co-precipitation method. Site occupancies of Zn2+, Cr3+ and Fe3+ ions were analyzed using X-ray diffraction data and Buerger's method. The effect of the constituent phase variation on the magnetic hysteresis behavior was examined by saturation magnetization which decreases with the increase in Cr3+ content in place of Fe3+ ions at octahedral B-site. Typical blocking temperature (TB) around 90K was observed by zero field cooling and field cooling magnetization study. Room temperature Mössbauer spectra show two paramagnetic doublets (tetrahedral and octahedral sites). The isomer shifts of both doublets decrease whereas quadrupole splitting and relative area of tetrahedral A-site increases with increasing Cr3+ substitution. The dielectric constant (measured on compositions x=0, 0.4, 0.8 and 1.0) increases when the temperature increases as in the semiconductor. This behavior is attributed to the hopping of electrons between Fe2+ and Fe3+ ions with a thermal activation.

Differences of the magnetic hysteresis behaviors in the magnetostructural transformation Mn1−xVxCoGe alloys

The magnetic hysteresis behaviors and the magnetocaloric properties of the Mn1−xVxCoGe (x=0.01 and 0.02) alloys in the heating and cooling runs have been investigated comparatively in the vicinity of the first-order magnetostructural phase transition. The magnetic hysteresis behaviors reveal an evident discrepancy between the heating and cooling processes. The average hysteresis losses estimated from the initial magnetization isotherms M(H) measured upon cooling are much larger than that upon heating. Considering the thermodynamics conditions and the potential barrier of phase transition, we analyzed the possible origin for this discrepancy and discussed the effects on the magnetocaloric properties for these two alloys.

Magnon supersolid and anomalous hysteresis in spin dimers on a triangular lattice

We study the magnetic phase diagram and hysteresis behavior of weakly coupled spin dimers on a triangular lattice using the cluster mean-field method with cluster-size scaling. We find that the magnetization curve has plateaus at 1/3 and 2/3 of the total magnetization, in which local singlet and triplet states form a superlattice pattern. Moreover, if increasing (decreasing) the magnetic field from the 1/3 (2/3) plateau, the Bose-Einstein condensation (BEC) of triplons occurs on the superlattice background, leading to the transition into magnon supersolid phase. We also find that the first-order transition between these solid states and the standard magnon BEC state exhibits an anomalous hysteresis upon cycling the magnetic field; the transition can occur only from solid to BEC, and the system cannot return to the initial solid state in the reverse process.

Dynamic magnetic properties of the kinetic cylindrical Ising nanotube

The nature (time variation) of response magnetizations m(wt) of the kinetic cylindrical Ising nanotube in the presence of a periodically varying external magnetic field h(wt) is studied by employing the effective-field theory (EFT) with correlations as well as the Glauber-type stochastic dynamics. We have determined the time variations of m(wt) and h(wt) for various temperatures, and investigated the dynamic magnetic hysteresis behavior. Temperature dependence of the dynamic magnetizations, hysteresis loop areas and correlations are investigated in order to characterize the nature (first- or second-order) of the dynamic transitions as well as to obtain the dynamic phase transition temperatures. We also present the dynamic phase diagrams in the three different planes and compare the results of the equilibrium and nonequilibrium states. The phase diagrams exhibit dynamic tricritical, isolated critical, multicritical and triple points. The results are in good agreement with some experimental and theoretical results.

Magnetic and electrical properties of CuFe2O4/BaTiO3 bilayer thin films

The magnetic and the electrical properties of CuFe2O4/BaTiO3 thin films grown on highly-textured Pt(111)/TiO2/SiO2/Si(100) substrates were studied. Sintered BaTiO3 and CuFe2O4 pellets prepared by the conventional mixed oxide process were used as targets during deposition by using the ion-beam sputtering and the pulsed laser deposition techniques. The film structure is of a bilayer type, where the BaTiO3 layer lies underneath the CuFe2O4 layer. The CuFe2O4/BaTiO3 film stack was then annealed at a temperature between 700 and 750 °C, followed by either FC (fast-cooling) or SC (slow-cooling) treatment. The ferroelectric and the electrical properties were measured using a ferroelectric test system, a digital multimeter, and an impedance analyzer. The Magnetic hysteresis (M-H) behavior at room temperature was measured using a vibration sample magnetometer (VSM), and the maximum saturation magnetization (M s ) and coercivity (H c ) values were 700 emu/cm3 and 325 Oe, respectively.

Inducing multiple functionalities in ZnS nanoparticles by doping Ni+2 ions

In this study, we propose that it is possible to induce multiple functionalities such as optical activity, electrical conductance and magnetism in single ZnS/Ni nanoparticles and exploit the same by only changing the external stimuli such as magnetic field, wavelength of light, electric field etc. Such type of material finds great significance in the field of electronics as well as in bioimaging. For the purpose, we have synthesized cubic ZnS:Ni2+ nanoparticles (NPs) using a simple wet-chemical method. Synthesized ZnS:Ni2+ NPs had been characterized by X-ray diffraction pattern (XRD) and energy dispersive X-ray (EDX) analysis. The amounts of Ni and Zn in the material were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Morphology of the NPs is studied by transmission electron microscopy (TEM). Optical studies are carried out using UV–visible (UV–Vis) and Photoluminescence (PL) spectroscopies. Quantum efficiency of the material was also computed. The enhancement and quenching of the PL intensity are correlated with the ‘purity of the phase’. It is observed that change in packing of the molecules of the host material directly depended on concentration of dopant ion. The thermal study of the material was carried out using differential scanning calorimetry (DSC) to support the earlier proposition. Magnetic hysteresis behavior was studied using vibrating sample magnetometer (VSM). An interesting phenomenon of defect-induced magnetism was observed, which was enhanced on doping with Ni+2.

WITHDRAWN: An Evaluation of Modern Pottery from Southern Africa as a Magnetic Recorder

AbstractStudies of the recent history of Earth's magnetic field have revealed a rich spatial and temporal structure, but face limitations by a lack of Southern Hemisphere archeomagnetic data. Studies of Iron Age (200‐1850 AD) peoples of southern Africa have revealed a potentially rich source of archeomagnetic information in the form of ceramics (specifically pottery). Additionally, contemporary pottery made with traditional techniques and materials can still be found. Reported here is the first step in addressing whether ancient pottery from southern Africa might faithfully record the geomagnetic field. We analyze contemporary pottery made with traditional techniques and methods. Rock magnetic measurements, including magnetic susceptibility as a function of temperature and magnetic hysteresis behavior, are discussed. Intensity results generated by three common paleointensity methods: Thellier‐ Coe double heating experiments, the multi‐specimen method of Dekkers and Böhnel, and Shaw's method (with and without the corrections of Kono) are compared to the known field at the time of firing. The Thellier‐Coe method reproduces the field (with an accuracy of 1.3 μT), the Shaw technique with the correction approach of Kono overestimates the field by 3.7%. The multispecimen method overestimates the field by 20%, however improvement upon this could be expected given recent improvements to the technique. These values bound the accuracies we can expect when applying the methods to ideal samples, representing a best‐case for dealing with archeological ceramics from southern Africa

Multicritical Dynamic Phase Diagrams and Dynamic Hysteresis Loops in a Mixed Spin-2 and Spin-5/2 Ising Ferrimagnetic System with Repulsive Biquadratic Coupling: Glauber Dynamic Approach

The stationary states of the kinetic mixed spin-2 and spin-5/2 Ising ferrimagnetic system with repulsive biquadratic coupling are examined within a mean-field approach under the presence of a time varying (sinusoidal) magnetic field. We employ Glauber-type stochastic dynamics to construct a set of coupled mean-field dynamic equations, and we solve these equations to find the phases in the system. We also investigate the thermal behavior of the dynamic order parameters to characterize the nature (continuous or discontinuous) of the dynamic phase transitions (DPTs) and obtain the DPT points. The phase diagrams are presented in the reduced magnetic field amplitude and reduced temperature plane, and a comparison is made with the results of other kinetic mixed spin systems. We also study the behavior of the dynamic magnetic hysteresis and investigate the effects of the frequency on hysteresis properties, and we find the results are in good agreement with some previous theoretical and experimental works.

Magnetic properties of MnO nanocrystals dispersed in a silica matrix

Magnetic nanocrystalline MnO particles have been synthesized in a silica glass matrix by the sol–gel method at calcination temperatures up to 1000°C. EPR spectra of 0.1mol% MnO doped silica gel and glasses studied in the temperature range 10–290K show with the exception of those samples calcined at 900 and 1000°C 6-line characteristic Mn(II) hyperfine (HF) lines. Additionally five spin-forbidden doublets have been observed at 100K and below. Small spreads in spin Hamiltonian parameters (D and E) imply that the ligand field environments of Mn(II) ions embedded in the silica glass are nearly uniform. Monotonous decrease in HF linewidth in going from 120°C gel to 800°C calcined glass has been interpreted as the continuous decrease in population of isolated Mn2+ ions in silica glass matrix resulting in the decrease of magnetic dipolar interactions leading to the observed decrease in HF linewidth. XRD and TEM of sample calcined at 1000°C shows the presence of nanocrystals of MnO having orthorhombic crystalline phase and sizes about 10nm. The thermal behavior of magnetization (zero-field-cooled and field-cooled) and magnetic hysteresis of MnO nanocrystals in the 5–300K temperature interval have demonstrated that the MnO nanocrystals display superparamagnetic–ferromagnetic transition at low temperatures. X-band EPR linewidth data plotted versus inverse of temperature (1/T) for samples calcined at 900 and 1000°C (EPR recorded in the vicinity of 0.35T applied field) depict similar transitions.

Dynamic magnetic hysteresis behavior and dynamic phase transition in the spin-1 Blume–Capel model

The nature (time variation) of response magnetization m(wt) of the spin-1 Blume–Capel model in the presence of a periodically varying external magnetic field h(wt) is studied by employing the effective-field theory (EFT) with correlations as well as the Glauber-type stochastic dynamics. We determine the time variations of m(wt) and h(wt) for various temperatures, and investigate the dynamic magnetic hysteresis behavior. We also investigate the temperature dependence of the dynamic magnetization, hysteresis loop area and correlation near the transition point in order to characterize the nature (first- or second-order) of the dynamic transitions as well as obtain the dynamic phase transition temperatures. The hysteresis loops are obtained for different reduced temperatures and we find that the areas of the loops are decreasing with the increasing of the reduced temperatures. We also present the dynamic phase diagrams and compare the results of the EFT with the results of the dynamic mean-field approximation. The phase diagrams exhibit many dynamic critical points, such as tricritical (•), zero-temperature critical (Z), triple (TP) and multicritical (A) points. According to values of Hamiltonian parameters, besides the paramagnetic (P), ferromagnetic (F) fundamental phases, one coexistence or mixed phase region, (F+P) and the reentrant behavior exist in the system. The results are in good agreement with some experimental and theoretical results.

Magnetic properties of nanocrystalline La0.52Sr0.28Mn1.2O3

Phase-pure La0.52Sr0.28Mn1.2O3 manganite nanopowders with average crystallite sizes of 30, 60, and 200 nm have been synthesized using coprecipitation and multiple cold isostatic pressing at 1 GPa. The crystallite size is shown to have a significant effect on the electrical and magnetic properties of the nanopowders: with decreasing particle size, their resistivity rises by several orders of magnitude, their Curie temperature decreases significantly, and the peak in their magnetic susceptibility broadens. The electrical and magnetic properties of powder compacts are compared to those of ceramic samples. The powder compacts show conventional magnetic hysteresis behavior, whereas the ceramics produced by sintering the compacts at 1270 K have an anomalous hysteresis. A mechanism is proposed that accounts for the anomalous hysteresis behavior.

Study of valence band structure of Fe doped anatase TiO2 thin films

We study the structural and electronic properties of Fe doped (4–8 at. %) and undoped TiO2 thin films deposited by pulsed laser deposition on Si(111) substrate. The films grow in single phase anatase structure of TiO2 as revealed by x-ray diffraction and Raman spectroscopy measurements. The Fe doped films reveal room temperature magnetic hysteresis behavior. We have probed the electronic environment of Fe in TiO2 matrix and its coupling to the cations, using photoelectron spectroscopy measurements. Photoelectron spectroscopic studies reveal the ionic state of Fe in TiO2, precluding the formation of Fe metal clusters. Valence band spectra of these films suggest that it primarily consists of O-2p derived state, however, Fe derived state is also observed in Fe doped films. Resonance photoelectron spectroscopy studies indicate that Fe ions are hybridized with Ti3+ defect states.

Structural and magnetic properties of nanocrystalline bismuth manganite obtained by mechanochemical synthesis

We have studied the formation of BiMnO3 (BMO) nanocrystalline perovskite powder produced by high-energy milling of the constituent oxides. The crystal structure and the amount of crystalline and amorphous phases in the powder as a function of the milling time were determined with XRPD using Rietveld refinement. BMO perovskite formed directly from highly activated nano-sized constituent oxides after 240 min of milling and subsequently grew during prolonged milling. The morphology, structure, and chemical composition of the powder were investigated by SEM and TEM. A clear ferromagnetic transition was observed at T C ~66 K for a sample milled for 240 min and increased with milling time. The magnetic hysteresis behavior is similar to that of a soft ferromagnet. The magnetic properties of the obtained BMO powders were found to change as a function of milling time in a manner consistent with variations in the nanocomposite microstructure.

Pentacobalt(ii) cluster based pcu network exhibits both magnetic slow-relaxation and hysteresis behaviour

A pentacobalt(II) cluster based 3D pcu network, [Co(5)(μ(3)-OH)(2)(bpdc)(4)(dabco)(H(2)O)(2)] (bpdc = benzophenone-2,4'-dicarboxylate and dabco = 1,4-diazabicyclo[2,2,2] octane), exhibiting both slow magnetic relaxation and hysteresis behavior, has been hydrothermally synthesized.

The influence of Al substitution on the phase transitions and magnetocaloric effect in Ni 43Mn 46Sn 11− xAl x alloys

The effects of Al substitution on the phase transitions and magnetocaloric effect of Ni 43Mn 46Sn 11− x Al x ( x=0–2) ferromagnetic shape memory alloys were investigated by X-ray diffraction and magnetization measurements. With the increase of Al content, the cell volume decreases due to the smaller radius of Al, and the martensitic transformation temperature increases rapidly, while the Curie temperature of austenitic phase shows a small increase. A large positive and a negative magnetic entropy change were observed near the first-order martensitic transition and the second-order magnetic transition, respectively. The magnetic entropy changes, hysteresis behavior, and refrigerant capacity near the two transitions are compared.

울릉도 해안지역 염기성암의 자기적 성질 연구

울릉도의 해안지역에서 염기성암 시료에 대하여 X-선 형광 분광 분석, M<TEX>$\ddot{o}$</TEX>ssbauer 분광 분석 및 SQUID 분석으로 물리적 특성을 조사하여 화산암의 화학적 조성과 시료 내에 존재하는 Fe의 원자가 상태와 자기적 성질을 연구하였다. 울릉도 해안지역의 염기성암은 알칼리 장석 계열의 광물들이 주 광물로 구성되어 있으며, 적철석인 hematite(<TEX>${\alpha}-Fe_2O_3$</TEX>)을 포함한 총 Fe 화합물의 중량비는 10.6~14.5 wt%의 범위에 있음을 알 수 있었다. M<TEX>$\ddot{o}$</TEX>ssbauer spectrum과 자기이력 곡선을 조사한 결과로 부터 모든 시료들의 자기적 성질이 hematite(<TEX>${\alpha}-Fe_2O_3$</TEX>)에 의한 강자성을 나타내고 있음을 알 수 있었다. 또한 10 K~350 K 온도 범위에서 외부 자기장인 +1 T를 인가하고 온도에 따른 자기화의 변화를 측정한 결과로부터 41 K~60 K 사이의 온도에서 시료들의 자기전이가 나타나고 있음을 알 수 있었다. Magnetic properties of basic rocks samples distributed in the seaside area of Ulleung island were investigated by means of X-ray fluorescence spectroscopy (XRF), M<TEX>$\ddot{o}$</TEX>ssbauer spectroscopy and SQUID magnetometer. We found that samples were typical basic rock which had the total amount of iron compounds varies from 10.6 wt% to 14.5 wt% depending on the different regions by XRF. The M<TEX>$\ddot{o}$</TEX>ssbauer spectra and magnetic hysteresis behaviors of the samples show ferromagnetic properties due to hematite. Also, temperature dependences of magnetization at applied magnetic field of 1 T for samples show magnetic transitions at 41 K~60 K.

Magnetic Mesoflowers: Synthesis, Assembly, and Magnetic Properties

An efficient method to introduce magnetic attributes to highly complex Au mesostructures by overlayer growth is demonstrated. The overlayer is nanostructured in all the cases investigated. A possible mechanism for the reduction of ions on the surface of Au mesoflowers and the consequent formation of hybrid mesoflowers is discussed. We studied the magnetic hysteresis behavior of Au/Ni, Au/Co, and Au/Pt/Ni mesoflowers at room temperature. Compared to the bulk metals, a decrease in saturation magnetization was observed in all the three hybrid magnetic mesoflowers, which may be due to the nanoscale structure. Assemblies of various magnetic mesoflowers extending over hundreds of micrometers on indium tin oxide (ITO) substrates have been made by magnetic field-induced self-assembly. Particles are assembled to form elongated chains, oriented parallel to the direction of the applied magnetic field.