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We report on the low temperature magnetic behavior of an epitaxially grown multilayer formed by 32 repetitions of a nominal period corresponding to 1 monolayer (ML) Co and 16 ML Ag. The study of the magnetic properties was based on the measurement of the temperature dependencies of the dc magnetization upon field cooling (FC) and zero field cooling (ZFC) and of the ac field real and imaginary parts of the susceptibility. From our results we conclude about the occurrence of i) a well-defined bilayers stacking sequence matching the nominal one, ii) a discontinuous growth in the Co layers resulting on close-to-monodisperse, spherical Co nanoparticles having an average diameter of 1.6 nm, iii) a frequency dependent peak in the temperature dependence of the real part of the ac susceptibility exhibiting a per decade relative temperature variation of 4.5 x 10−2, iv) an applied dc field, Hdc, variation of the temperature at which the irreversibility is detected in the FC/ZFC curves corresponding to the Almeida-Thouless prediction, and v) a critical behavior characterized by a glass-transition temperature slightly below the peak temperatures observed at low frequency in the temperature dependence of the ac susceptibility and a dynamic scaling exponent in the range of the values usually obtained for spin glass systems. From our results we conclude that i) our sample experiences a superspin-glass/paramagnetic phase transition, ii) the interactions mediating the spin glass freezing process are the dipolar ones taking place among the Co particles (creating fields at the average interparticle distance of the order of 8 x 105 A/m) which provide competitiveness that combined with the reduced amount of disorder built-in the Co layers results on frustration. [ABSTRACT FROM AUTHOR]

We report a strong variation of the magnetic properties and of the antiphase boundaries (APBs) density of Fe3O4(001) epitaxial thin films grown on thin Fe(001) and Cr(001) buffer layers on a MgO(001) substrate in comparison with similar magnetite films grown directly on MgO(001). The magnetization of the Fe/Fe3O4 and Cr/Fe3O4 bilayers presents a more squared hysteresis loop and reach saturation at much lower magnetic field (∼10–15 kOe) than the Fe3O4 thin films of same thickness, which hardly saturate at 70 kOe. The magnetization of the magnetite layers has been estimated on both the Fe- and Cr-based samples and a value close to that of the bulk Fe3O4 has been obtained, which points to the magnetic saturation of the Fe3O4 layer induced by the metallic buffers. Transmission electron microscopy has been used to investigate the possible structural origin of this phenomenon studying the APB network of Fe3O4 in the three types of samples. The calculation of the average domain size reveals that the APB density in the bilayers is substantially reduced in comparison with their counterparts without buffer. The domain sizes obtained in Fe and Cr samples are similar, which points to a structural origin probably due to the strain caused by the lattice misfit between the buffers and the magnetite. A lower APB density statistically reduces the influence of the antiferromagnetic interactions existing across some of the boundaries, achieving the saturation of the Fe3O4 layer at much lower magnetic fields. [ABSTRACT FROM AUTHOR]

We report a strong variation of the magnetic properties and of the antiphase boundaries (APBs) density of Fe3O4(001) epitaxial thin films grown on thin Fe(001) and Cr(001) buffer layers on a MgO(001) substrate in comparison with similar magnetite films grown directly on MgO(001). The magnetization of the Fe/Fe3O4 and Cr/Fe3O4 bilayers presents a more squared hysteresis loop and reach saturation at much lower magnetic field (∼10–15 kOe) than the Fe3O4 thin films of same thickness, which hardly saturate at 70 kOe. The magnetization of the magnetite layers has been estimated on both the Fe- and Cr-based samples and a value close to that of the bulk Fe3O4 has been obtained, which points to the magnetic saturation of the Fe3O4 layer induced by the metallic buffers. Transmission electron microscopy has been used to investigate the possible structural origin of this phenomenon studying the APB network of Fe3O4 in the three types of samples. The calculation of the average domain size reveals that the APB density in the bilayers is substantially reduced in comparison with their counterparts without buffer. The domain sizes obtained in Fe and Cr samples are similar, which points to a structural origin probably due to the strain caused by the lattice misfit between the buffers and the magnetite. A lower APB density statistically reduces the influence of the antiferromagnetic interactions existing across some of the boundaries, achieving the saturation of the Fe3O4 layer at much lower magnetic fields. [ABSTRACT FROM AUTHOR]

An extensive investigation on the magnetism of Gd5(SixGe1-x)4 compounds which stabilize in the Gd5Si4-type structure is here presented, focusing on the Gd5Si4 and Gd5Si2Ge2 compositions. Through Arrott plot analysis, the temperature dependencies of the spontaneous magnetizations are retrieved and the magnetic interaction coefficients (Jexch) are estimated. The obtained Jexch value for Gd5Si4 is 15% higher than that of Gd5Si2Ge2. Such enhancement cannot be attributed to a magneto-volume coupling only, being mainly associated with the magnetic polarization of the (Si,Ge)-(Si,Ge) interslab connections. The critical exponents were estimated (δ=3.1 and 2.9, γ=1.01 and 1.06, β=0.48 and 0.56, and n=0.67 and 0.63 for Gd5Si4 and Gd5Si2Ge2, respectively) demonstrating that both compositions belong to the same universal class. This conclusion is reinforced by the construction of a universal logarithmic scaling plot of the M(H) isothermal curves. Hence, we conclude that the magnetism of the Gd5Si4-type structure compounds is simply dominated by long range ferromagnetic interactions. This contrasts to other Gd5(SixGe1-x)4 compositions where a strong competition antiferro versus ferromagnetic interactions and short versus long range order are observed. Finally, the Gd5Si4 composition has shown a reduction of 50% on the magnetic entropy change maxima when compared with the Gd5Si2Ge2 compound studied, despite its higher magnetic interaction coefficient value. [ABSTRACT FROM AUTHOR]

In this work, we report a systematic study of the influence of film thickness on the structural and magnetic properties of epitaxial thin films of Pr2−δNi1−xMn1+xO6−y (PNMO) double perovskite grown on top of two different (001)-SrTiO3 and (001)-LaAlO3 substrates by RF magnetron sputtering. A strong dependence of the structural and magnetic properties on the film thickness is found. The ferromagnetic transition temperature (TC) and saturation magnetization (Ms) are found to decrease when reducing the film thickness. In our case, the thinnest films show a loss of ferromagnetism at the film-substrate interface. In addition, the electronic structure of some characteristic PNMO samples is deeply analyzed using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) measurements and compared with theoretical simulations. Our results show that the oxidation states of Ni and Mn ions are stabilized as Ni2+ and Mn4+, thus the ferromagnetism is mainly due to Ni2+-O-Mn4+ superexchange interactions, even in samples with poor ferromagnetic properties. XMCD results also make evident large variations on the spin and orbital contributions to the magnetic moment as the film's thickness decreases. [ABSTRACT FROM AUTHOR]

Cylindrical magnetic nanowires are promising materials that have the potential to be used in a wide range of applications. The versatility of these nanostructures is based on the tunability of their magnetic properties, which is achieved by appropriately selecting their composition and morphology. In addition, stochastic behavior has attracted attention in the development of neuromorphic devices relying on probabilistic magnetization switching. Here, we present a study of the magnetization reversal process in multisegmented CoNi/Cu nanowires. Nonstandard 2D magnetic maps, recorded under an in-plane magnetic field, produce datasets that correlate with magnetoresistance measurements and micromagnetic simulations. From this process, the contribution of the individual segments to the demagnetization process can be distinguished. The results show that the magnetization reversal in these nanowires does not occur through a single Barkhausen jump, but rather by multistep switching, as individual CoNi segments in the NW undergo a magnetization reversal. The existence of vortex states is confirmed by their footprint in the magnetoresistance and 2D MFM maps. In addition, the stochasticity of the magnetization reversal is analysed. On the one hand, we observe different switching fields among the segments due to a slight variation in geometrical parameters or magnetic anisotropy. On the other hand, the stochasticity is observed in a series of repetitions of the magnetization reversal processes for the same NW under the same conditions. [ABSTRACT FROM AUTHOR]

This work presents the evolution of morphological, structural and magnetic properties of amorphous Fe-Ni wire-like nanochains caused by thermal oxidation. The initial Fe1−xNix samples (x = 0.75; 0.50; 0.25) were prepared through the magnetic-field-induced synthesis, and then they were heated in dry air at 400 °C and 500 °C. These treatments led to two competing simultaneous processes occurring in the investigated samples, i.e., (i) a conversion of amorphous material into crystalline material, and (ii) their oxidation. Both of them strictly affected the morphological and structural properties of the Fe-Ni nanochains which, in turn, were associated with the amount of iron in material. It was found that the Fe0.75Ni0.25 and Fe0.50Ni0.50 nanochains were covered during thermal treatment by the nanoparticle oxides. This coverage did not constitute a good barrier against oxidation, and these samples became more oxidized than the Fe0.25Ni0.75 sample which was covered by oxide nanosheets and contained additional Ni3B phase. The specific morphological evolutions of the Fe-Ni nanochains also influenced their saturation magnetizations, whereas their coercivities did not vary significantly. The obtained results constitute an important source of information for future application of the thermally treated Fe-Ni nanochains which could be applied in the energy storage devices or catalysis. [ABSTRACT FROM AUTHOR]

Platelet shaped strontium hexaferrite (SrFe12O19) crystallites were hydrothermally synthesized in an autoclave to study the effect of (a) Fe/Sr molar ratio, (b) choice of base NaOH/KOH and (c) base concentration. The influence of these parameters on the final product is evaluated with regards to phase composition, structure and magnetic properties. Rietveld refinements were performed on powder x-ray diffraction (PXRD) data to determine the phase composition, structural changes, crystallite sizes, and preferred orientation, while the magnetic properties were measured using a vibrating sample magnetometer. When NaOH is used as the base, the samples consist mostly (>95 wt.%) of SrFe12O19 up to the same molar ratio of Fe/Sr = 8, independent of the concentration of the base. In contrast, when using KOH, the phase composition depends on both the molar ratio of Fe/Sr and the concentration of KOH. High concentrations of Sr2+ and OH− (Fe/Sr = 1 and OH−/NO3− = 4) result in the growth of wide crystallites (>400 nm). The thickness of the crystallites are in all cases around 40 nm causing the crystallites to have an anisotropic shape, which can align without applying an external magnetic field. In the case of KOH as base instead of NaOH, an expansion of the unit cell is observed, which can be attributed to K+ substituting Sr2+ in the structure. This is corroborated by increasing microstrain when increasing the KOH/NO3− ratio. Variations in the observed coercivity may be attributed to substitution of Sr2+ by K+. The present study illustrates that meticulous control of all reaction parameters and a meticulous analysis of the crystal structure is key for preparing and understanding hard-magnetic SrFe12O19. [ABSTRACT FROM AUTHOR]

Fe–Ni nanoparticles are attractive candidates for magnetic cores of transformers and inductors that are operated at high frequencies. When applying Fe–Ni nanoparticles in magnetic cores, particle size must be controlled to enhance magnetic properties. A two-step synthetic method can be useful for fabricating size-controlled Fe–Ni nanoparticles. In the first step, Ni nanoparticles are synthesized by reducing Ni (II) acetylacetonate in oleylamine (OA) with trioctylphosphine (TOP). Thereafter, Fe (III) acetylacetonate is reduced and Fe atoms diffuse into the preformed Ni nanoparticles in OA. The size of the Fe–Ni nanoparticles depends on that of the Ni nanoparticles. However, no studies have conducted extensive investigations of their synthesis and magnetic properties with various particle sizes. Here, we attempted particle-size-controlled synthesis of Fe–Ni nanoparticles and investigated their magnetic properties. The particle size of the Fe–Ni nanoparticles was varied between 13.1. and 20.5 nm by varying the size of Ni nanoparticles. The saturation magnetization (Ms) gradually reduced with the decrease in particle size because of the increased amount of oxidized surface atoms and phosphides. Coercive forces (Hc) also decreased as the particle size decreased to 15 nm because of the increased effect of superparamagnetism, while the Hc greatly increased with the particle size reduction below 14 nm because of the ferromagnetism exhibited by the Fe layer owing to undiffused Fe atoms. Thus, using this synthetic method, Fe–Ni nanoparticles with a size of approximately 15 nm can be produced, which have a minimum Hc and are the most appropriate for magnetic cores. [ABSTRACT FROM AUTHOR]

Summary: The growth of cobalt nanopatterns (NPs) using focused electron‐beam induced deposition (FEBID) for localised magnetic studies is presented. The initial FEBID products are shown to be polycrystalline and form hetero‐structured core‐shell NPs through surface oxidation. Off‐axis electron holography is performed to reconstruct their morphology, thickness profile and image their individual magnetic vortex domain states. In situ annealing to 400°C promoted migration of the Co‐overspray to grow the Co NPs and improved their crystallinity through coarsening, as well as induced diffusion of embedded carbon out of their surface. It is found that the change in their morphology and chemical instability under heating restricts their suitability for examining thermally induced magnetic variations. Lay Description: In this paper, electron microscopy is used to deposit magnetic cobalt nanopatterns and characterise the effect of in‐situ heating on their chemistry, structure and magnetic properties. The electron beam of the secondary electron microscope is used to dissociate an injected precursor gas near the SiN membrane substrate of in‐situ transmission electron microscopy (TEM) chips and locally deposit the elemental Co in circular patterns ∼ 90 nm in diameter. TEM reveals formation of a Co‐oxide shell and embedding of carbon from the precursor gas during growth. The technique of electron holography is used to image the magnetism of the core‐shell Co / Co‐oxide nanopatterns, which are shown to exhibit magnetic vortex states. In‐situ annealing results in migration of the Co overspray to increase their height and carbon diffusion from their surface, as well as change in their original magnetic state through change of orientation. It is found that the change in the morphology and chemistry of Co nanopatterns under heating limits their use for studying the effect of temperature on their magnetism in isolation. [ABSTRACT FROM AUTHOR]

Thin films of [Co(0.3 nm)/Ni(0.6 nm)]4, 10 multilayers (MLs) stack were deposited on Si and glass substrates using DC magnetron sputtering. The magnetic stack layers were deposited under various conditions such as (i) without using any under layer (referred as-prepared film) (ii) with Cu under-layer (iii) with in situ annealing of Ta/Cu under-layer (iv) with in situ along with post annealing of overall magnetic stack. The as prepared [Co(0.3 nm)/Ni(0.6 nm)]4 films deposited on Si as well as on glass substrate exhibit perpendicular magnetic anisotropy (PMA) as per magnetization measurements at room temperature. Inserting Cu under layer to this magnetic stack helps to enhance the coercivity (HC), saturation magnetization (MS) and the squareness [MR/MS] of the films in comparison to as-prepared MLs. Thin films of MLs with in-situ annealing of Ta/Cu, further enhance the value of MS and Sq in comparison to as-prepared and with Cu-under layer MLs. Even though the HC, MS and squareness [MR/MS] of M-H loop of post annealed films are comparable to the films prepared under other three conditions, the PMA was observed only in the latter case. Additionally, on increasing the number of magnetic bi-layers of the stack from 4 to 10 i.e. [Co (0.3 nm)/Ni (0.6 nm)]10, it is observed that the magnetic property parameters such as HC, MS and Sq were enhanced along-with exhibiting perpendicular magnetic anisotropy (PMA). The observation of PMA in these films may be due to the growth of Cu along (111) direction and Co/Ni (111) crystalline orientation, as demonstrated by XRD pattern and the topography analyses by AFM. [ABSTRACT FROM AUTHOR]

Cubic spinel CoCr2O4 has recently attained attention due to its multiferroic properties. However, the Co site substitution effect on the structural and magnetic properties has rarely been studied in thin film form. In this work, the structural and magnetic properties of Co1–xNixCr2O4 (x= 0, 0.5) epitaxial thin films deposited on MgAl2O4 (100) and MgO (100) substrates to manipulate the nature of strain in the films using pulsed laser deposition (PLD) technique are presented. The epitaxial nature of the films was manifested through x-ray diffraction (XRD), reciprocal space mapping (RSM) and Rutherford backscattering spectrometry (RBS) measurements. Raman measurements revealed a disappearance of characteristic A1g and F2g modes of the CoCr2O4 with increase in the Ni content. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM) studies show a modification of the surface morphology upon Ni substitution. Magnetic measurements disclose that the ferrimagnetic Curie temperature (TC) of the CoCr2O4 in thin film grown on MgAl2O4 (100) and MgO (100) substrates were found to be 100.6 ± 0.5 K and 93.8 ± 0.2 K, respectively. With Ni substitution the TC values were found to be enhanced to 104.5 ± 0.4 K for MgAl2O4 (100) and 108.5 ± 0.6 K for MgO (100) substrates. X-ray photoelectron spectroscopy (XPS) suggests Cr3+ oxidation states in the films, while Co ions are present in a mixed Co2+/Co3+ oxidation state. The substitution of Ni at Co site significantly modifies the line shape of the core level as well as the valence band. Ni ions are also found to be in a mixed 2+/3+ oxidation state. O 1s core level display asymmetry related to possible defects like oxygen vacancies in the films. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate the magnetic properties and the ground state phase diagrams of the double perovskite La2NiMnO6 using the Monte Carlo simulations (MCS). Design/methodology/approach: In this work, the authors propose a Hamiltonian modeling this compound, described by an Ising model, with different exchange coupling interactions J11, J12 and J22 between the only magnetic atoms Ni and Mn. Findings: Starting with the ground state phase diagrams, the authors present and discuss the stable configurations in different physical parameter planes. On the other hand, the authors present the investigation of the magnetic properties and the magnetization behaviors of the magnetic susceptibilities, as a function of temperature, crystal field, the exchange coupling interactions and the Zeeman energy. To complete this study, the authors illustrate the dependency of the total magnetizations for the hysteresis loops of the double perovskite La2NiMnO6 compound. This study is done for fixed values of temperature, the exchange coupling interactions and crystal field. Originality/value: The authors modeled the different physical parameters of the double perovskite La2NiMnO with a Hamiltonian describing the system. At T=0K, the authors discussed the ground state phase diagrams of different physical parameters planes. For non-null temperature values, the authors studied the magnetic behavior of the double perovskite La2NiMnO using MCS under the metropolis algorithm. The authors expect that the results of these simulations can provide some important keys for the experimental research and technology applications of the double perovskite La2NiMnO6 in the future. [ABSTRACT FROM AUTHOR]

Multifunctional materials having simultaneous electrical and magnetic assembling have been attempted by numerous researchers for next-generation electronic appliances. Among such materials, rare earth metals containing double perovskites, such as La2BB′O6 (B = Ni, B′ = Mn) are the utmost studied materials. In this review, we have summarized various physicochemical aspects of La2NiMnO6 such as crystal structure, electrical, magnetic, and magneto-transport behavior from earlier studies under several experimental conditions. Magnetic field and temperature effects on magnetoelectric and electronic behavior of this material are described. We discuss how the morphology in the form of bulk phase, thin layer, and nanoparticles affect such physicochemical properties of this material. We also highlighted the role of cation order–disorder at 'B' sites and the probability of the resulting numerous electronic behavior in this type of material and expectation on basic understanding of Ni–O–Mn electronic, as well as magnetic properties. The prospective applications of this material over conventional substances in solar cells, electric tunable devices, biomolecular and gas sensing technologies are also ascribed. The motivation of the present review is to sum up all such behaviors of La2NiMnO6 to find its possible applications in new areas of material research and the directions of future works. Highlights: La2NiMnO6 double perovskite exhibits simultaneous electric and magnetic orderings Crystal structure, magneto-electric, and transport nature affect the functionality of La2NiMnO6 Bulk phase, thin layer, and nanoparticles morphology affect the physical property of La2NiMnO6 La2NiMnO6 holds solar cell, electric tunable device, biomolecular and gas sensing applications [ABSTRACT FROM AUTHOR]

The magnetic and magnetocaloric properties of Ho5Si4 have been investigated. The compound undergoes a second order ferromagnetic transition at 76 K (TC) and a spin reorientation transition at about 15 K. The temperature dependencies of heat capacity data measured in various magnetic fields corroborate the second order ferromagnetic character of the transition at TC. For a field change (ΔH) of 50 kOe, the maximum values of isothermal magnetic entropy change (ΔSM) and adiabatic temperature change (ΔTad) are -14.8 J kg-1 K-1 (114 mJ/cm3 K) and 6.1 K, respectively. From the first principles calculations the TC of Ho5Si4 is estimated to be 78 K and the maximum value of ΔSM is estimated to be -12.6 J kg-1 K-1 for ΔH=50 kOe [ABSTRACT FROM AUTHOR]

LaCaMnO compounds with the crystallite size of D = 45-200 nm were synthesized by utilizing the solid-state reaction and mechanical ball milling methods. The reduction of the crystallite size ( D) resulted in the decrease of both T and magnetization, broadening of the phase transition region, and appearance of Griffiths phase features in the materials. The temperature dependence of saturation magnetization ( M), the variations of the coercivity ( H), and the deviation of magnetization from expected Bloch's law T for these samples were also investigated. Based on the core-shell model, the core diameter and the nonmagnetic shell thickness for the samples were determined. [ABSTRACT FROM AUTHOR]

• Indium chemical substitution is promising for tuning and for unveiling magnetocaloric atomic scale behaviour. • Independently of the In substitution on Gd5Si1.2Ge2.8 (by Si, Ge, and Gd), In is insoluble in the magnetocaloric 5:4 phase. • Indium promotes and segregates into the 5:3 phase leading to a change of Si/Ge ratio on the 5:4 phase. • In substitution promotes: atomic disorder, unit cell expansion and a reduction of Gd5Si1.2Ge2.8 magnetocaloric effect. [Display omitted] Chemical substitution is one of the most efficient tools to tune and optimize magnetic and magnetocaloric properties of the giant magnetocaloric materials. In particular, Indium substitutions could be useful both for tuning properties of these interesting intermetallic materials and to unveil their local-scale behavior across the magnetostructural transition via hyperfine techniques. Hence, in order to investigate the effect of Indium additions on the crystal structure, micro-structure, magnetic and magnetocaloric properties, a series of In-containing samples derived from the base Gd 5 Si 1.2 Ge 2.8 stoichiometry were prepared. The major findings are that while In is insoluble in the 5: 4 phase, it will instead promote the emergence of the impurity 5: 3 phase and segregates into this phase. Hence, In leads to major crystallographic changes, which enhance atomic disorder and disrupt the Si to Ge ratio in the 5: 4 phase. Subsequently, a higher 5: 4 unit cell volume and a lower magnetic ordering temperature are found in the In-substituted samples. Finally, the magnetocaloric properties of the In-substituted samples reveal a detrimental effect on the maximum magnetic entropy change. [ABSTRACT FROM AUTHOR]

Our recent studies of the crystal structures, phase transitions, and magnetic properties of intermetallic compounds R5M4 (R = rare earths; M = Si, Ge) are reviewed briefly. First, crystal structures, phase relationships, and magnetic properties of several 5:4 compounds, including Nd5Si4−xGex, Pr5Si4−xGex, Gd5−xLaxGe4, La5Si4, and Gd5Sn4, are presented. In particular, the canted spin structures as well as the magnetic phase transitions in Pr5Si2Ge2 and Pr5Ge4 investigated by neutron powder diffractions and small-angle neutron scattering are reviewed. Second, the crystal structures and magnetic properties of the most studied compounds Gd5(Si,Ge)4 are summarized. The focus is on the parent compound Gd5Ge4, which is an amazing material exhibiting magnetic anisotropy, angular dependent spin-flop transition, metastable magnetic response, Griffiths-like phase, thermal effect under pulsed fields, antiferromagnetic and ferromagnetic resonances, pronounced effects of impurities, and high-field induced magnetic transitions. [ABSTRACT FROM AUTHOR]

The first-order phase transition in Gd5Si2Ge5 is sensitive to both magnetic field and pressure. It may indicate that the influences of the magnetic field and the pressure on the phase transition are virtually equivalent. Moreover, theoretical analyses reveal that the total entropy change is almost definite at a certain Curie temperature no matter whether the applied external field is a magnetic field or a pressure. The entropy change curve can be broadened dramatically under pressure, and the refrigerant capacity is improved from 284.7 J/kg to 447.0 J/kg. [ABSTRACT FROM AUTHOR]

The magnetic and transport properties of pulsed laser-deposited Co100−x–Cux thin films were tailored through their nano-morphology and composition by controlling for the deposition geometry, namely normal or oblique deposition, and their Cu content. All films were composed of an amorphous Co matrix and a textured growth of Cu nanocrystals, whose presence and size d increased as x increased. For x = 50, all films were superparamagnetic, regardless of deposition geometry. The normally deposited films showed no in-plane magnetic anisotropy. On the contrary, controllable in-plane uniaxial magnetic anisotropy in both direction and magnitude was generated in the obliquely deposited films. The magnetic anisotropy field Hk remained constant for x = 0, 5 and 10, Hk ≈ 35 kAm−1, and decreased to 28 and 26 kAm−1 for x = 20 and 30, respectively. This anisotropy had a magnetostatic origin due to a tilted nano-sheet morphology. In the normally deposited films, the coercive field Hc increased when x increased, from 200 (x = 0) to 1100 Am−1 (x = 30). In contrast, in obliquely deposited films, Hc decreased from 1500 (x = 0) to 100 Am−1 (x = 30) as x increased. Activation energy spectra corresponding to structural relaxation phenomena in obliquely deposited films were obtained from transport property measurements. They revealed two peaks, which also depended on their nano-morphology and composition. [ABSTRACT FROM AUTHOR]

The paper presents studies of microstructure, magnetic and corrosion properties of the Gd58Ge20Si22, Gd56Ge20Si22Co2, Gd56Ge20Si22Ti2 and Gd56Ge20Si22Cr2 (at.%) alloys after isothermal heat treatment at 1450 K for 2 h. The structure investigations of the produced materials performed by X-ray diffraction show the presence of Gd5Ge2Si2-type phase in all investigated samples. DC and AC magnetic measurements confirmed that the Curie temperature depends on the chemical composition of the produced alloys. From M(T) characteristics, it was found that the lowest Curie point (TC = 268 K) was estimated for the Gd58Ge20Si22 sample, whereas the highest value of the Curie temperature (TC = 308 K) was for the Gd56Ge20Si22Cr2 alloys. Moreover, the GdGeSi alloy without alloying additions shows the highest magnetic entropy change |ΔSM| = 15.07 J⋅kg−1⋅K−1 for the maximum magnetic field of 2 T. The maximum |ΔSM| measured for the Gd56Ge20Si22 with the addition of Co, Ti or Cr for the same magnetic field was obtained in the vicinity of the Curie point and equals to 2.92, 2.73 and 2.95 J⋅kg−1⋅K−1, respectively. Electrochemical studies of the produced materials for 60 min and 55 days exposure in 3% NaCl solution show that the highest stability and corrosion resistance were exhibited the sample with added of Ti. [ABSTRACT FROM AUTHOR]

Focused electron beam induced deposition (FEBID) is a direct-write nanofabrication technique able to pattern three-dimensional magnetic nanostructures at resolutions comparable to the characteristic magnetic length scales. FEBID is thus a powerful tool for 3D nanomagnetism which enables unique fundamental studies involving complex 3D geometries, as well as nano-prototyping and specialized applications compatible with low throughputs. In this focused review, we discuss recent developments of this technique for applications in 3D nanomagnetism, namely the substantial progress on FEBID computational methods, and new routes followed to tune the magnetic properties of ferromagnetic FEBID materials. We also review a selection of recent works involving FEBID 3D nanostructures in areas such as scanning probe microscopy sensing, magnetic frustration phenomena, curvilinear magnetism, magnonics and fluxonics, offering a wide perspective of the important role FEBID is likely to have in the coming years in the study of new phenomena involving 3D magnetic nanostructures. [ABSTRACT FROM AUTHOR]

Magnetic structures have attracted a great interest due to their multiple applications, from physics to biomedicine. Several techniques are currently employed to investigate magnetic characteristics and other physicochemical properties of magnetic structures. The major objective of this review is to summarize the current knowledge on the usage, advances, advantages, and disadvantages of a large number of techniques that are currently available to characterize magnetic systems. The present review, aiming at helping in the choice of the most suitable method as appropriate, is divided into three sections dedicated to characterization techniques. Firstly, the magnetism and magnetization (hysteresis) techniques are introduced. Secondly, the visualization methods of the domain structures by means of different probes are illustrated. Lastly, the characterization of magnetic nanosystems in view of possible biomedical applications is discussed, including the exploitation of magnetism in imaging for cell tracking/visualization of pathological alterations in living systems (mainly by magnetic resonance imaging, MRI). [ABSTRACT FROM AUTHOR]

Abstract: In this work we report detailed measurements of the electrical resistivity ρ(T), thermopower S(T) and magnetization M(T) of Er5Si4 near the structural and magnetic phase transitions. These transitions are well decoupled, with the structural transition occurring at T S =190K (on cooling) and the magnetic transition occurring at T C ∼30K. The large thermal hysteresis occurring in the structural transition demonstrates its first-order nature being accompanied with a strong variation ΔS/S essentially due the change in the number of carriers. Our magnetic and transport measurements below the magnetic phase transition suggest the presence of weak ferromagnetism. [Copyright &y& Elsevier]

We have performed a detailed study on the structure and magnetic properties for Co2FeSi (CFS) alloy films deposited on the MgO(0 0 1) substrates with or without a Cr buffer layer. With the increase of CFS thickness, the structure ordering degree increases, leading to an improved biaxial magnetic anisotropy. Nevertheless, in spite of the reduced lattice misfit between MgO and CFS, XRD results reveal that the insertion of a 2.5 nm thick Cr layer could give rise to the loss of CFS ordering, which has been ascribed to the interfacial diffusion of Cr atoms caused by thermal annealing. As the Cr buffer thickness is increased more than 10 nm, it is found that the chemically ordered CFS structure reappears, showing a weak four-fold symmetry. Nevertheless, as compared to the CFS films without a Cr buffer, the biaxial magnetic anisotropy rotates by 45°, with two magnetic easy axes transforming from the directions of MgO〈1 1 0〉/CFS〈1 0 0〉 to MgO〈1 0 0〉/CFS〈1 1 0〉. We consider that the observed orientation transition of biaxial magnetic anisotropy results from the competition between the Cr/CFS interfacial contribution and the intrinsic bulk CFS contribution. Our results provide a better understanding of the evolution of crystalline structure and in-plane magnetic anisotropy with increasing the CFS and Cr layer thicknesses, which will be helpful for designing advanced spintronic devices. [ABSTRACT FROM AUTHOR]