Maximum Magnetic Susceptibility Research Articles

Variation of color of magnetic noise in Er3+ molecular magnets contacting metal surface in ferromagnetic composite

Interaction between single molecule magnets (SMMs) and metal surface is a hot topic promising controllable deposition of SMMs, programmable frequency of magnetic relaxation and addressed reading of information. In this paper, we develop strategy of the Er3+ based SMM functionalization by its penetration inside the arrays of Ferromagnetic Micro Particles (FMPs). We show that predictable residual magnetic field of the FMPs arrays is an effective tool for regulation of the frequency maximum of imaginary magnetic susceptibility. We analyzed color of magnetic noise in respect to physical origin of magnetic relaxation. An additional channel for control over spin noise is formation of chemical bonds between SMM and the FMPs surface. Oxidation of an Er complex transforms 20 ± 5 % of the initial 10-coordinated SMM complex to the 9-coordinated complex with reduced relaxation time. Memorized residual magnetization of the composite material allows one to set desirable relaxation frequency in the individual micronized cells to create a sound frequency register. The proposed compaction of SMMs of different types in ferromagnetic composites provides engineering of the chemically designed spin interface on ferromagnetic surface for spintronics and quantum computing.

Studying the Crucial Physical Characteristics Related to Surface Roughness and Magnetic Domain Structure in CoFeSm Thin Films

This study investigated the effects of varying film thicknesses and annealing temperatures on the surface roughness and magnetic domain structure of CoFeSm thin films. The results revealed that as the film thickness increased, both the crystalline size and surface roughness decreased, leading to a reduction in coercivity (Hc) and improved magnetic contrast performance. Energy-dispersive X-ray spectroscopy (EDS) analysis confirmed the presence of cobalt (Co), iron (Fe), and samarium (Sm) within the thin films. Notably, the 40 nm Co40Fe40Sm20 thin film annealed at 200 °C exhibited lower sheet resistance (Rs) and resistivity (ρ), indicating higher conductivity and a relatively higher maximum magnetic susceptibility (χac) at 50 Hz. These findings suggest that these films are well suited for low-frequency magnetic components due to their increased spin sensitivity. The 40 nm Co40Fe40Sm20 thin film, subjected to annealing at 200 °C, displayed a distinct stripe domain structure characterized by prominently contrasting dark and bright patterns. It exhibited the lowest Hc and the highest saturation magnetization (Ms), leading to a significant improvement in their soft magnetic properties. It is proposed that the surface roughness of the CoFeSm thin films plays a crucial role in shaping the magnetic properties of these thin magnetic films.

Studying the Effects of Annealing and Surface Roughness on Both the Magnetic Property and Surface Energy of Co60Fe20Sm20 Thin Films on Si(100) Substrate

In this study, Co60Fe20Sm20 alloy was employed for sputter deposition onto Si(100) substrate within a high vacuum environment, and subsequent thermal treatment was conducted using a vacuum annealing furnace. Thorough measurements and analyses were carried out to evaluate how various film thicknesses and annealing temperatures affect the material. The investigations encompassed observations of structural and physical properties, magnetic traits, mechanical behavior, and material adhesion. The results from the four-point probe measurements clearly demonstrate a trend of decreasing resistivity and sheet resistance with increasing film thickness and higher annealing temperature. Analysis through atomic force microscopy (AFM) shows that heightened annealing temperature corresponds to decreased surface roughness. Furthermore, when analyzing low-frequency alternating current magnetic susceptibility (χac), it became evident that the maximum magnetic susceptibility value consistently rises with increased film thickness, regardless of the annealing temperature. Through magnetic force microscopy (MFM) observations of magnetic domain images in the films, it became apparent that there was a noticeable reduction in the brightness contrast of the magnetic domains. Furthermore, nanoindentation analysis reveals a clear trend. Elevating the film thickness leads to a reduction in both hardness and Young’s modulus. Contact angles range between 67.7° and 83.3°, consistently under 90°, highlighting the hydrophilic aspect. Analysis of surface energy demonstrates an escalation with increasing film thickness, and notably, annealed films exhibit a substantial surge in surface energy. This signifies a connection between the reduction in contact angle and the observed elevation in surface energy. Raising the annealing temperature causes a decline in surface roughness. To summarize, the surface roughness of CoFeSm films at different annealing temperatures significantly impacts their magnetic, electrical, and adhesive properties. A smoother surface reduces the pinning effect on domain walls, thus enhancing the χac value. Furthermore, diminished surface roughness leads to a decline in the contact angle and a rise in surface energy. Conversely, rougher surfaces exhibit higher carrier conductivity, contributing to a reduction in electrical resistance.

Iron removal from kaolinitic coal gangue via magnetic separation after oxidizing calcination with the crystal structure of kaolinite protected

Iron is a harmful color-staining impurity that degrades the performance of coal gangue (CG) products, and pyrite is the predominant form of iron in kaolinitic coal gangue. In addition, iron extraction from CG as a supplemental iron ore resource is significant for increasing the added value of CG comprehensive utilization. Herein, calcination in a mild oxidizing atmosphere was implemented to enhance the magnetic properties of pyrite for subsequent magnetic separation. The sample was calcined at 300–1000 °C for 30–180 min, and the maximum magnetic susceptibility reached approximately 17 times that of the original ore. The iron recovery rates of the gangue calcined for 60–120 min were increased remarkably to 83.17–83.61%, while the iron recovery rate of the raw gangue was almost zero. After magnetic separation, the Fe2O3 content decreased from 5.58% for the raw gangue to 1.00% for the nonmagnetic products of gangues calcined for 60–120 min. Retention of the strongly magnetic magnetite, which was an intermediate product in the oxidation of pyrite to hematite, enabled the effective removal of iron from the gangue. Additionally, the kaolinite in the iron-removed coal gangue basically maintained its crystal structure.

Effect of Magnesium Treatment on Cleanliness, Microstructure, and Magnetic Properties of Fe–80Ni Permalloy

Cleanliness and microstructure significantly impact the magnetic properties of soft magnetic materials. This study investigates the impact of Mg treatment on the cleanliness, microstructure, and magnetic properties of Fe–80Ni alloy. The content of Mg ranges from 0% to 0.034%. The O and S contents can be reduced to 0.0006% and 0.0011%, respectively, when the content of Mg is 0.027%, and the number of inclusions is reduced. Simultaneously, the primary inclusions are modified to Mg‐containing inclusions. Based on electron backscattered diffraction results, Mg treatment can refine the deformed grain and enhance grain boundary energy after cold rolling. In addition, the grains exhibit enhanced growth after annealing with Mg treatment. Due to the improvement of cleanliness and microstructure, the magnetic properties of Fe–80Ni alloy are enhanced with Mg treatment. With Mg treatment, the coercivity of alloys is reduced, and maximum magnetic susceptibility (χmax) increases to 0.3247 with Mg treatment, while that is 0.1938 without Mg treatment.

The Influence of Annealing and Film Thickness on the Specific Properties of Co40Fe40Y20 Films

Cobalt Iron Yttrium (CoFeY) magnetic film was made using the sputtering technique in order to investigate the connection between the thickness and annealing procedures. The sample was amorphous as a result of an insufficient thermal driving force according to X-ray diffraction (XRD) examination. The maximum low-frequency alternate-current magnetic susceptibility (χac) values were raised in correlation with the increased thickness and annealing temperatures because the thickness effect and Y addition improved the spin exchange coupling. The best value for a 50 nm film at annealing 300 °C for χac was 0.20. Because electron carriers are less constrained in their conduction at thick film thickness and higher annealing temperatures, the electric resistivity and sheet resistance are lower. At a thickness of 40 nm, the film's maximum surface energy during annealing at 300 °C was 28.7 mJ/mm2. This study demonstrated the passage of photon signals through the film due to the thickness effect, which reduced transmittance. The best condition was found to be 50 nm with annealing at 300 °C in this investigation due to high χac, strong adhesion, and low resistivity, which can be used in magnetic fields.

Magnetic susceptibility of a ternary Ising nanoisland

We investigate magnetic properties of a ternary ( 1 / 2 , 1, 3 / 2 ) bilayer Ising nanoisland with an 18-site quadratic structure. By employing exact enumeration, we study the effects of crystal fields, exchange couplings and thermal fluctuations on the magnetic susceptibility and blocking temperature. As a result, we find several scenarios in which a double peak structure in the thermal dependence of the magnetic susceptibility can be observed. In particular, the competition between core–shell antiferromagnetic interactions and the external magnetic field can drive an additional low-temperature maximum in the magnetic susceptibility. In addition, the competition between core–shell couplings and a strong crystal field in the core spins can also provide a scenario in which the magnetic susceptibility shows two maximum. From the magnetic susceptibility maximum at higher temperatures, we estimate the blocking temperature. Surprisingly, we note that an increase in the absolute value of the exchange couplings can reduce the blocking temperature. Moreover, our findings suggest that the mechanism driving the double maxima in the magnetic susceptibility also provides a context in which the increase in the strength of the exchange coupling can lead to a reduction in the blocking temperature. Therefore, our results allow us to describe different scenarios in which double-peak structures in the magnetic susceptibility of nanoparticles can be spotted, also suggesting that these scenarios can favor a reduced blocking temperature. • Magnetism of a mixed-spin (1/2,1,3/2) nanoisland with core–shell structure has been investigated. • Effects of crystal fields and exchange couplings are evaluated. • Thermal dependence of magnetic susceptibility shows a double-peak structure. • Blocking temperature shows non-monotonic dependence on the core–shell couplings.

Processing of the zinc-lead-bearing flotation middlings by sulfidizing roasting with pyrrhotites production by predicted properties

The accumulated amount of lead-zinc ore flotation tailings in the dumps of concentrating plants today can be considered as independent man-made deposits. In addition to their resource value as sources of lead and zinc, as well as associated gold, silver, cadmium, selenium and other metals, tailings are an environmentally hazardous source of heavy metal pollution of ground and surface waters. The environmental hazard of stale tailings is exacerbated by the fact that they occupy large areas that cannot be used for agricultural or other purposes of the national economy. Wastes of flotation enrichment of lead-zinc ores significantly differ from the source material not only in the content of minerals, but also in the degree of oxidation of their surface, fractional composition, and the presence of a significant amount of mineral intergrowths. In view of this, the use of existing flotation technologies is ineffective for obtaining standard lead and zinc concentrates from enrichment tailings. This paper describes the technology that has been developed for processing of zinc and lead-bearing enrichment wastes by sulfidizing roasting followed by magnetic and flotation concentration of cinders. It was found that, as a result of the sulfidizing- pyrrhotizing roasting process, the flotation ability increases for lead compounds and decreases for iron compounds, while the magnetic susceptibility of lower iron sulfides formed during roasting increases. It has been established that sulfidizing takes place with sufficient completeness, and during subsequent flotation, it is possible to extract up to 95% of zinc and up to 80% of lead into sulfide concentrate. These results have a technological advantage in contrast to the other methods that have been used. It was found that at roasting temperatures of 700–800 °C, pyrrhotites have a maximum magnetic susceptibility of 3.75, 5.43 and 2.18 SI units for Fe0.855S, Fe0.888S and Fe0.909S, respectively. Technological recommendations are acceptable for similar raw materials. The research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan Grant №AP08052829.

Pressure effect on the structural, magnetic and thermophysical properties of X12Cr13 martensitic stainless steel prepared by powder metallurgy method

Low carbon (C: 0.03-0.15%) and high Cr contents (Cr: 11-15%) martensitic stainless steel (MSS) is widely used for industrial applications due to its good mechanical properties and corrosion resistance. In this study, we investigated the pressure effect on the structural, magnetic and thermophysical properties of X12Cr13 MSS which was compacted using powder metallurgy method under 400 and 600 MPa pressures and sintered at 1200 °C temperature for an hour under Ar atmosphere. Pressing and sintering processes resulted in increased density of microstructures from 5.84 g/cm 3 to 6.12 g/cm 3 , decreased porosity from 7.58% to 3.39%, increased hardness from 93.24 HB to 110.09 HB (N/ mm 2 ) and decreased carbide particles from 2.65% to 2.13 wt% in the structures. We observed α -Fe, γ -Fe and M 23 C 6 (M: Cr or Fe) phase formations in the structure due to the applied pressure and the sintering process. The magnetic properties of these steels have been investigated as a function of temperature between 300-400 K and applied magnetic field of ±4 T. We observed improved magnetic properties with increasing pressure, and ferromagnetic to paramagnetic phase transition occurred from 300 K to 400 K. While maximum saturation magnetization is found to be 70 emu/g at 300 K for 600 MPa sample, maximum magnetic susceptibility and permeability for 600 MPa sintered sample are recorded as 17.13 and 1.08 m 3 /kg, respectively. Also, the maximum specific heat capacity and enthalpy are recorded as 1.85 J/g °C and 536.05 J/g (at 579 °C temperature) on the sample compacted on the 600 MPa pressure, respectively. • X12Cr13 MSS samples were prepared by P/M method at 400 MPa and 600 MPa. • 600 MPa pressing and 1200 °C sintering enhanced physical and magnetic properties • MSS prepared at 600 MPa exhibits 110.09 HB hardness and 6.12 g/cm 3 density. • The maximum saturation magnetization found to be 70 emu/g at RT for 600 MPa sample. • The 600 MPa sample provided 536.0 J/g heat storage capacity at 579°C.

Theoretical investigation of the magnetic properties of ferromagnetic CrI3 monolayer

The CrI3 monolayer is the first ferromagnetic two-dimensional material experimentally discovered and the study of its properties is a hot topic. First-principles calculations and experimental measurements show that the CrI3 monolayer is a typical S=3/2 localized magnetic system. In the present work, we investigated the intrinsic magnetic properties of CrI3 monolayer based on the anisotropic Heisenberg model and using the double-time Green’s function method. The Hamiltonian parameter values of CrI3 monolayer are estimated theoretically based on the experimental Curie temperature of CrI3 monolayer and the experimental magnetic parameters of CrI3 bilayers. The spontaneous magnetization and zero-field susceptibility are calculated, and the critical behaviors of the system are analyzed. We observe that the maximum magnetic susceptibility value is sensitive to the isotropic exchange parameter and external magnetic field, but almost independent of anisotropic strengths.

Significance of Granulometric Composition and Physicochemical Properties for Interpreting the Lake Grand Sedimentation

Abstract —The paper is concerned with a study of the slope deposits being weathering products of rhyolites and their tuffs in the vicinity of Lake Grand (northern Okhotsk area). The samples were divided into grain size fractions of 2500, 250, 140, 100, 63, 40, 20, and 1 μm. Analysis for major and trace elements and mineralogical and petrophysical studies were performed for each fraction. It is shown that a decrease in the fraction size is accompanied by the enrichment of the sediments with Al2O3, Fe2O3, TiO2, MgO, Y, Rb, Ni, and paramagnetic minerals and by an increase in LOI. The fine fractions are characterized by low contents of SiO2 and Na2O and high values of CIA, PIA, and Rb/Sr. The maximum magnetic susceptibility, saturation magnetization, and contents of CaO, Sr, and Zr are established in the fractions of 40 μm. The values of magnetic susceptibility, Js, and Jrs decrease in passing from the fractions of 40 μm to the fractions of 1 μm, whereas the values of Bc and Bcr increase. A specific feature of these fractions is high paramagnetic susceptibility and the presence of lepidocrocite. The qualitative composition of ferrimagnetic minerals is the same for the slope deposits and lacustrine sediments. In passing from coarse fractions to fine ones, the contents of quartz and K-feldspar decrease, and the contents of muscovite, biotite, chlorite, and kaolinite increase. The distribution of petromagnetic and geochemical characteristics in the Lake Grand sediments of varying grain size is similar to that in the slope deposits. The complex characteristics of the lacustrine sediments that formed in cold and warm periods are consistent with the distribution of these parameters in various fractions of deluvium and colluvium. Moreover, the fine-grained material acquired specific geochemical, mineralogical, and petrophysical properties when being on the slopes. Comparison of the SiO2/TiO2 and Fe2O3/TiO2 ratios of the slope deposits and lacustrine sediments makes it possible to identify the intervals of biogenic and chemogenic sedimentation in water basins.

Magnetic fabrics as strain markers in folded soft-sediment layers

We exploit the potential of magnetic fabrics acting as strain markers in folded layers, by analysing an exceptionally well-exposed, recent (<1 kyr) slump horizon in unlithified lake deposits within the Dead Sea basin. The ∼3-m-long folded soft-sediment layer, together with an underlying basal detachment, and an ‘undeformed’ reference layer are extensively sampled (n = 97) for an anisotropy of magnetic susceptibility (AMS) analysis. This analysis reveals deformation fabrics within the folded layer which are significantly different from fabrics detected in the ‘undeformed’ layer. The maximum magnetic susceptibility axes (K1) show a hinge-parallel orientation, and the minimum magnetic susceptibility axes (K3) show a trail of orientations directed eastward parallel to the direction of downslope slumping toward the depocenter of the basin. In terms of shape of the AMS, samples from the ‘undeformed’ layer are oblate, while the majority of samples from the fold backlimb are oblate to neutral, and those from the forelimb and hinge zones are more prolate. We postulate that the deformation shown by the AMS analysis approximates well to sections through the strain ellipsoid in the folded layer, suggesting that magnetic fabrics serve as strain markers that are invisible to the naked eye. The deformation fabrics are created by particles moving relative to one another and reorganising during hydroplastic deformation. Particles physically rotate in the hinge zone, resulting in shortening of the intermediate axes and creation of more prolate shapes. The combination of two types of fabrics (deposition and deformation) in the hinge zones increases the intensity of the lineation due to the intersection of the primary and secondary fabrics (foliations). Based on the dense sampling scheme, we produce GIS-based interpolation maps that show the spatial distribution of the AMS parameters in the folded layer. These maps are compared to data from classical strain analyses, providing a benchmark for combining traditional structural methods and AMS analyses in studying folding and soft-sediment deformation.

Reconstruction of subglacial depositional conditions based on the anisotropy of magnetic susceptibility: an example from Dębe (central Poland)

ABSTRACTThe analysis of low‐field anisotropy of magnetic susceptibility (AMS) was used to reconstruct the subglacial deposition conditions during the Main Stadial of the Odranian Glaciation (MIS 6) in till deposits from a site in Dębe (central Poland). Based on the AMS parameters, six till beds were identified (intervals 1–6). The declination of the maximum magnetic susceptibility axis (k1) indicates that the ice sheet was moving in from the northwest. The obtained results confirm the thesis about the preferred direction of ice‐sheet transgression during the Odranian Glaciation (MIS 6) in this part of Poland. This interpretation is also confirmed by data obtained from measurements of the long axis of clasts, which agree with the orientation of k1. Based on the AMS results, a significant part of the profile was deformed through simple shear and direct interaction of the ice sheet with the underlying sediment (beds 2–5). The lowest part of the till (bed 6) may have been deposited on a southeast‐trending slope or post‐depositional deformed by uneven loading of the ice cover. The upper part of the profile (especially in interval 1) could be deposited with an impact of pore water.

Updating the significance and paleoclimate implications of magnetic susceptibility of Holocene loessic soils

Mass specific magnetic susceptibility variation with depth along soil profiles developed on loess parent material is one of the most frequently used physical parameter in local, regional and global correlations of loess deposits. It is also utilized as a paleo-precipitation proxy, defined either as absolute difference between susceptibilities of the enhanced B-horizon and parent loess C-horizon; or relative enhancement, using ratios of magnetic parameters. In the present study we compare and analyze the applicability of various approaches in establishment of the empirical relationships between pedogenic magnetic enhancement of Holocene soils from Bulgarian lower Danube area, published data from cCentral and Eastern Europe, and the Chinese loess, and climate parameters – mean annual precipitation (MAP) and mean annual temperature (MAT). Unlike previous studies, which compile data from soils, developed on various parent materials, using maximum magnetic susceptibility of the B-horizon and mean of the C-horizon, we strictly utilize soils, developed on loess material only and consider minimum susceptibility signal in the underlying loess unit. The data analysis shows that minimum magnetic susceptibility of the parent loess exhibits strong relation to climate’s parameters as well. We show that by using minimum magnetic susceptibility of the C-horizon to correct for the detrital input, pedogenic enhancement shows significant multiple correlation with both MAP and MAT. This relationship is different for Chinese and European sites but it is not retained for sites, located at low river terraces, Black sea coast and soils having increased coarse silt and sand content. Grouping the sites according to present day vegetation cover reveals the presence of uniform linear relationship between pedogenic susceptibility enhancement and climate parameters mostly for locations with steppe vegetation, while mixed steppe-forest and forest sites reveal more scattered and steeper relation to MAT and MAP variations.

Effect of milling on structure and magnetism of nanocrystalline La0.7-xBixSr0.3MnO3 (x = 0.35, 0.40) manganites

Polycrystalline bulk samples of La0.7-x BixSr0.3MnO3 (x = 0.35 and 0.40) manganites have been subjected to high energy planetary ball milling to prepare nanoparticles by using the top-down approach. A significant drop in the particle size has been observed with an increase in milling time. The high temperature magnetic transitions get broader and suppressed while the low temperature maxima in magnetic susceptibility overshadows the high temperature transition. The field dependent magnetization studies describe the competitive coexistence of antiferromagnetic (AFM) and ferromagnetic (FM) interactions in x = 0.35, whereas for x = 0.40, the magnetic ground state is dominantly AFM. The magnitude of magnetization reduces with milling, which could be explained by core-shell model. Detailed analysis of X-ray diffraction, neutron diffraction, and magnetization studies are presented to understand the role of Bi3+ as well as particle size on structure and magnetism.

Interpreting Inverse Magnetic Fabric in Miocene Dikes From Eastern Iceland

AbstractAnisotropy of Magnetic Susceptibility (AMS) is a valid tool to investigate magma flow direction within dikes. However, geometrically inverse magnetic fabric characterized by maximum magnetic susceptibility axis (kmax) perpendicular to the dike wall may complicate the interpretation of flow trajectories. To better understand the nature of this fabric, we present a multiscale study on 19 dikes (383 samples) in the Miocene Alftafjordur volcanic system (Iceland), where 80% of the samples show a geometrically inverse magnetic fabric. We carried out (1) AMS measurements at different magnetic fields and temperatures, along with Anisotropy of Anhysteretic Remanent Magnetization (AARM) analysis; (2) hysteresis loops and FORC diagrams; (3) thin section analysis; (4) structural fieldwork. A variable Ti‐content (0.1 &lt; x &lt; 0.6, Fe3‐xTixO4) titanomagnetite is the main magnetic carrier, and the contribution of the paramagnetic elongated crystals to the magnetic fabric is negligible. Single domain is not the prevailing domain state of the magnetic particles, suggesting that its occurrence cannot be the main cause for the inverse fabric. AMS analysis at different fields and temperatures along with AARM allow us to exclude any mineral phase change of the titanomagnetite across the dike. Nevertheless, kmax is parallel to a diffuse horizontal column‐like fracture pattern perpendicularly oriented with respect to the dike strike. This suggests that the Ti‐magnetite mineral orientation during dike cooling was affected by the fracture network progressively developing columnar basalts. This study demonstrates that the interpretation of AMS data on old and deep volcanic bodies is not straightforward and observations at different scales are required.

Temperature dependence of the Kondo resonance in the photoemission spectra of the heavy-fermion compounds YbXCu4(X=Mg,Cd,andSn)

We report a temperature-dependent study of Kondo resonance in the heavy-fermion compounds $\mathrm{Yb}X{\mathrm{Cu}}_{4}$ with $X=\mathrm{Mg}$, Cd, and Sn. A sharp peak of the ${\mathrm{Yb}}^{2+}\phantom{\rule{4pt}{0ex}}4{f}_{7/2}$ state has been observed in photoemission spectra, and its energy position in the limit of zero temperature is in agreement with the energy scale of the Kondo temperature ${T}_{\mathrm{K}}$. The peak develops in the form of a dispersionless peak with large spectral weight at ${T}_{\mathrm{coh}}$ well below ${T}_{\mathrm{K}}$. The onset temperature of the robust Kondo state is comparable to the temperature at a local maximum in magnetic susceptibility. This nontrivial development of changes in the Kondo resonance at ${T}_{\mathrm{coh}}$ demonstrates the formation of the coherent heavy-fermion state.

Crystal structure and magnetism in theS= 1/2 spin dimer compound NaCu2VP2O10

The crystal structure of the spin dimer magnet NaCu2VP2O10 was determined using single-crystal X-ray diffraction and electron diffraction. NaCu2VP2O10 displayed a non-centrosymmetric orthorhombic C2221 structure with a = 6.13860 (10) Å, b = 14.4846 (3) Å and c = 8.2392 (2) Å. The layered structure comprised CuO4 plaquettes, VO6 octahedra and PO4 tetrahedra. A pair of CuO4 plaquettes formed Cu2O6 structural dimers through edge sharing. The Cu-Cu network formed a distorted puckered-layer structure with pseudo-one-dimensional characteristics. Maximum magnetic susceptibility was observed at ∼60 K and NaCu2VP2O10 became non-magnetic upon further cooling. The spin gap between the spin-singlet non-magnetic ground state and triplet excited state was estimated to be 43.4 K. Thus, NaCu2VP2O10 was assumed to be an alternating chain system with a singlet ground state of dimer origin. The V5+ ions in the VO6 octahedra showed large off-centre displacements along the [110] direction in the primitive perovskite structure, which were attributed to the pseudo-Jahn-Teller distortion of d 0 transition metals.

Spin transmission in IrMn through measurements of spin Hall magnetoresistance and spin-orbit torque

Understanding the transport of spin current in antiferromagnetic materials is indispensable to develop antiferromagnetic spintronic devices. In this work, we study the spin current transmission through an antiferromagnetic IrMn insertion layer in a W/IrMn($t$)/CoFeB structure by measuring the spin Hall magnetoresistance (SMR) and spin-orbit torque (SOT). The temperature dependences of SMR and SOT effective fields indicate that the spin current transmission reaches its maximum at the N\'eel temperature of IrMn. The enhancement is ascribed to the increase in the interfacial spin mixing conductance, which is related to the maximum magnetic susceptibility of the IrMn layer at the N\'eel temperature. The spin transmission decreases monotonically as a function of the IrMn thickness, which is different from the case with an insulating antiferromagnetic NiO insertion layer in previous works. In addition, we found that the spin transmission through an antiferromagnetic IrMn layer is independent of the exchange bias orientation. Our results suggest that the spin current transmission through the IrMn layer (from W layer to CoFeB layer) is mainly mediated by spin-polarized electrons rather than magnons, which is likely due to the absence of the effective excitation of magnons in the IrMn layer by the spin-polarized current.

Magnetic Susceptibility of Ferromagnetic Alloy Material Co (1-x) Ni (x) Nanocube and Nanosphere Models

A hard disk is a data storage medium composed of a thin layer of magnetic material. Hard drives take advantage of the characteristics of magnetic materials that are stable to heat and have sensitivity to magnetic fields. One of the best materials to use a thin layer ferromagnetic on a hard disk is CoNi alloy. Hard drives with larger storage capacities require magnetic materials with high magnetic susceptibility values and Curie temperatures to obtain the best magnetic properties. The magnetic susceptibility of alloy ferromagnetic material Co (1- x) Ni (x) nanocube and nanosphere is calculated using vampire-based micro magnetic simulation. The research was conducted using a literature review on the parameters of the CoNi alloy material, and then it was simulated in the vampire program. The data generated from the simulation are magnetic susceptibility (1/tesla) and temperature (K). The spectrum of the magnetic susceptibility graph that shifts to the right as the Ni (x) composition decreases, it is assumed that the higher Curie temperature is produced. Otherwise, The increase in Ni (x) composition causes the magnetic susceptibility spectrum to shift to the left, with the Curie temperature's predicted value getting minor than the other. The nanocube-shaped material has a higher susceptibility value than the nanosphere-shaped material in terms of each Ni (x) composition variation at its maximum magnetic susceptibility.