La3+ doped yttrium iron garnet films have been grown on (111) oriented gadolinium gallium garnet substrates via Liquid phase epitaxy technique as a basic material for ISHE device fabrication. Pt as a material with a large spin hall angle was used as a spin detection layer. We investigated the dependence of the spin pumping effect on the power and frequency of the excitation microwaves in La:YIG/Pt bilayers by measuring the ISHE voltage. We demonstrated that the area under the ISHE curve(SISHE) across a wide power range had a nearly linear correlation with the input microwave power (Pin). The parameter SISHE can be used to describe the spin current energy in a Pt layer which can be a useful parameter for a microwave rectifier.

Magnetic skyrmions are particle-like, topologically protected magnetization entities that are promising candidates for information carriers in racetrack-memory schemes. The transport of skyrmions in a shift-register-like fashion is crucial for their embodiment in practical devices. Recently, we demonstrated experimentally that chiral skyrmions in Cu2OSeO3 can be effectively manipulated by a magnetic field gradient, leading to a collective rotation of the skyrmion lattice with well-defined dynamics in a radial field gradient. Here, we employ a skyrmion particle model to numerically study the effects of resultant shear forces on the structure of the skyrmion lattice. We demonstrate that anisotropic peak broadening in experimentally observed diffraction patterns can be attributed to extended linear regions in the magnetic field profile. We show that topological (5-7) defects emerge to protect the six-fold symmetry of the lattice under the application of local shear forces, further enhancing the stability of proposed magnetic field driven devices.

van der Waals (vdW) magnetic materials show promise in being the foundation for future spintronic technology. The magnetic behavior of Fe2.7GeTe2 (FGT), a vdW itinerant ferromagnet, was investigated before and after proton irradiation. Proton irradiation of the sample was carried out at a fluence of 1×1018 cm-2. The magnetization measurements revealed a small increase of saturation magnetization (Ms) of about 4% upon proton irradiation of the sample, in which, the magnetic field was applied parallel to the c-axis. X-ray photoelectron spectroscopy for pristine and irradiated FGT revealed a general decrease in intensity after irradiation for Ge and Te and an increase in peak intensity of unavoidable surface iron oxide. Furthermore, no noticeable change in the Curie temperature (TC =152 K) is observed in temperature dependent magnetization variation. This work signifies the importance of employing protons in tuning the magnetic properties of vdW materials.

Single-phase multiferroic materials have attracted considerable attention among scientists, due to the strong drive in industry towards device miniaturization, addition of new functionalities, etc. Currently, most of the discovered materials have at-least one ferroic order active only at low temperatures, thereby hindering their induction into practical devices. κ-Al2O3-type AlxFe2-xO3 (x-AFO) oxides belong to a new class of metastable multiferroic compounds (space group: Pna21), with relatively high Curie temperatures. The current work investigates the effect of thin film deposition conditions on the ferroelectric and ferrimagnetic properties of Al0.5Fe1.5O3 (0.5-AFO). Substrate temperature and oxygen partial pressure during deposition were found to be the critical parameters in obtaining high quality films. Optimizing the deposition conditions of 0.5-AFO enabled observation of both ferroelectricity and ferrimagnetism at room temperature.

Traditional synthesis of high-performance bulk ferrites include complex sintering procedures where temperature and soak times to obtain high densities and excellent magnetic properties. Most ferrites must be sintered at hundreds degree centigrade approaching or surpassing 1000oC, and for YIG (yttrium iron garnet), the sintering temperature should be approximately 1450°C. The high sintering temperatures limit the applications of ferrites, for example, the low temperature co-sintering of ceramics with silver electrodes and/or ground planes. For decades, researchers have explored the use of ion-doping, sintering aids, and microstructural refinement. Here, we study the optimization of the sintering profile including multiples temperature and soak times for doped Bi-YIG simples. The results show an improvement in soft magnetic and gyromagnetic properties attributed to the homogenization of grain size and morphology.

Thin films of insulating Ti1−xNixO2 (x = 0.00, 0.05, 0.10, and 0.15) are synthesized by the spray pyrolysis technique. All the films are seen to crystallize into polycrystalline anatase phase of TiO2. However, weak signature of the NiTiO3 phase is also observed for the films having higher Ni ion concentration. Optical absorption analysis suggests nonmonotonous band gap decrease from 3.67 to 3.59 eV with respect to added concentration of Ni ions unto ‘x’ = 0.10 in the TiO2 matrix. The presence of ferromagnetic ordering at room temperature in Ni incorporated TiO2 films is revealed by M–H measurements. Calculated values of saturation magnetization indicate that the observed ferromagnetism is not due to the presence of Ni clusters or segregation of other ferromagnetic phase. Electrically insulating nature of the films suggests that the observed FM ordering is most probably due to the ferromagnetic interaction between bound magnetic polarons which formed due to the creation of oxygen vacancies or defects.

Strong strain-mediated magnetoelectric (ME) coupling in magnetic/ferroelectric heterostructures has great potential for different high-frequency multiferroic devices. In this article, we present the most recent progress in integrated multiferroic devices. Integrated magnetic tunable inductors with a wide operation frequency range, integrated nonreciprocal bandpass filters with dual magnetic and electric-field tunability based on magnetostatics surface waves, and novel radio-frequency nanomechanical ME resonators with pico-Tesla sensitivity for direct current magnetic fields are presented. Finally, a new antenna miniaturization mechanism, acoustically actuated nanomechanical ME antennas, which can successfully miniaturize the size by 1–2 orders, is introduced. With the advantages of high magnetic field sensitivity, highest antenna gain among all nanoscale antennas at similar frequency, integrated capability with complementary metal oxide semiconductor technology, and ground-plane immunity from metallic surfaces and the human body, ME antennas have a bright future for biomedical applications, wearable antennas, and the Internet of Things due to their unique and particular properties.

Strong magnetoelectric (ME) coupling realized in magnetic/ferroelectric multiferroic heterostructures provides great potential for different integrated multiferroic devices for sensing, power, RF, and µ-wave electronics. Here, we present the most recent progress on new integrated multiferroic devices including novel integrated magnetic tunable inductors with a wide operation frequency range; integrated nonreciprocal bandpass filter with dual H- and E-field tunability based on magnetostatics surface waves; dual H- and E-field tunable RF bandpass filters with nanomechanical ME resonators; RF nanomechanical ME resonators with pico-Tesla DC magnetic fields sensitivity; a new antenna miniaturization mechanism, acoustically actuated nanomechanical ME antennas, which successfully miniaturize the magnitude in 1-2 orders with the advantages of the high magnetic field sensitivity, highest antenna gain within all nanoscale antennas at the similar frequency, and ground plane immunity on the metallic surface and the human body.

The magnetism and microstructure of Cr25Ni35Nb and Cr35Ni45Nb alloy tubes after 5 years of service were investigated in this paper. The saturation magnetization of the Cr25Ni35Nb alloy tube in the thickness direction is more than 20 emu/g, and the tube becomes ferromagnetic. The inner and outer walls of Cr35Ni45Nb alloy tubes also become ferromagnetic. But the saturation magnetization of the Cr35Ni45Nb alloy tubes approaches to zero in the center zone. The primary carbides M7C3 and NbC are changed into M23C6 and G phase at the outer region of the furnace tube. However, the M23C6-type carbides were replaced by carbon-rich carbides M7C3 at the carburization zone. Cr-depleted zones are formed at the inner and outer walls of the furnace tubes owing to oxidation. Carburization and oxidation reduce the Cr content of the matrix. Accordingly, the saturation magnetization is very high at the carburization zone and Cr-depleted zone. The magnetism of Cr25Ni35Nb and Cr35Ni45Nb alloy tubes has a high correlation with the Cr content of the matrix. Carburization and oxidation are the main reasons that make the paramagnetic ethylene pyrolysis furnace tube change to ferromagnetic.

In this project, we described the production of chrysin-loaded L-phenyl alanine (Phe)-coated iron oxide magnetic nanoparticles (chrysin@Phe@IOMNs). chrysin@Phe@IOMNs were characterized by X-ray diffraction, thermogravimetric analysis, fourier transform infrared spectroscopy, vibrating sample magnetometer, and transmission electron microscopy techniques. Next, hemocompatibility and biocompatibility of Phe-coated IOMNs were determined by hemolysis and MTT assays on HFF-2 and HEK-293 cell lines, respectively. Finally, the anticancer activity of chrysin@Phe@IOMNs was examined on MCF-7 cell line. The outcomes direct that as-prepared nanocarriers are nontoxic and biocompatible and also chrysin@Phe@IOMNs are appropriate for chrysin delivery and other hydrophobic therapeutic agents.

In Part I, equal channel angular extrusion (ECAE) was demonstrated as a novel, simple-shear deformation process for producing bulk forms of the low ductility Fe–Co–2V (Hiperco 50A®) soft ferromagnetic alloy with refined grain sizes. Microstructures and mechanical properties were discussed. In this Part II contribution, the crystallographic textures and quasi-static magnetic properties of ECAE-processed Hiperco were characterized. The textures were of a simple-shear character defined by partial {110} and 〈111〉 fibers inclined relative to the extrusion direction, in agreement with the expectations for simple-shear deformation textures of BCC metals. These textures were observed throughout all processing conditions and only slightly reduced in intensity by subsequent recrystallization heat treatments. Characterization of the magnetic properties revealed a lower coercivity and higher permeability for ECAE-processed Hiperco specimens relative to the conventionally processed and annealed Hiperco bar. The effects of the resultant microstructure and texture on the coercivity and permeability magnetic properties are discussed.

This article discusses recent studies of on-chip integration of a plasmonic isolator on a Si substrate and a hybrid isolator on an InP substrate. The key characteristics of the plasmonic isolator are reviewed and future prospects are discussed. A method to enhance the magneto-optical figure of merit (FOM) and reduce the propagation loss of a surface plasmon in order to realize the proposed design of the plasmonic isolator is described. One hundred percent enhancement of the FOM and 20× reduction of propagation loss in the optimized ferromagnetic plasmonic structure are experimentally demonstrated.

Ga2−xFexO3 (GFO) bulks with x from 0.7 to 1.3 have been fabricated using the classic solid-state route. The structural, optical, and magnetic properties have been investigated systematically. X-ray diffraction spectra and FULLPROF profile fitting indicate that GFO bulks belong to the orthorhombic structure with the space group Pc21n. Phase separation appears at the Fe content of x = 1.3. The optical bandgap decreases almost linearly with the increase of iron content, which means that the bandgap of GFO bulks can be controlled by adjusting the Fe content in the samples. The magnetic property measurements suggest that GFO is ferromagnetic, and the magnetic properties are enhanced compared with other reported works, exhibiting the application in ferromagnetic semiconductors devices.

Magnetocaloric heat pumps (MHPs) use the solid-state magnetocaloric effect (MCE) to move heat from cold to hot using an intermediate heat-transfer fluid. Work input is required to drive the MCE via a change in a magnetic field. Work input is also required to drive the heat-transfer fluid flow. Thus design of a MHP involves the coupling of materials, magnetics, heat transfer, and fluid flow. We discuss design principles and operational devices that have brought this technology toward technical feasibility, and the approaches to overcome remaining hurdles to commercial feasibility.

The fundamentals and applications of ferroic materials—ferromagnetic, ferroelectric, and ferroelastic—are common subjects discussed in just about every graduate course related to functional materials. Looking beyond today’s traditional uses, such as in permanent magnets, capacitors, and shape-memory alloys, there are worthwhile and interesting questions common to the caloric properties of these ferroic materials. Can ferroic materials be used in a cooling cycle? Why are these materials susceptible to external fields? Which combination of properties is required to make some of them suitable for efficient cooling and heat pumping? We address these questions in this introduction to ferroic cooling, which comprises magnetocaloric, electrocaloric, elastocaloric and barocaloric approaches and combinations thereof (i.e., multicalorics). These are addressed in greater detail in the articles in this issue.

Harvesting energy from otherwise wasted resources has been intensively investigated as a promising technology especially for enabling the deployment of autonomous wireless-sensor networks for the Internet of Things. Multi-stimulus energy harvesting, simultaneously from different energy sources, provides an attractive opportunity to amplify the power density of harvesters, thereby extending their potential for self-powered devices. In this article, we review recent and ongoing research efforts aimed at enhancing the energy-harvesting performance of magnetoelectric (ME) composite harvesters employing dual stimuli, mechanical vibrations, and magnetic fields. After a brief introduction to vibration, magnetic field, and dual-mode energy harvesting, we survey the key materials utilized for ME energy harvesting. We then focus on progress in this area and discuss relevant ideas to realize electromechanical and magnetoelectric coupling for harvesting energy from mechanical vibrations and magnetic fields simultaneously. We provide perspectives and future directions as well.

In this work, we study the hard-magnetic properties and its influence on the microstructure of MnBi-based glass-coated microwires obtained by Taylor-Ulitovsky process, as well as their magnetic and thermal dependence in the range of 200 K-360 K. We obtained glass-coated microwires pieces trough of the Taylor-Ulitovsky process. Glass-coated microwires exhibited the formation of Low-Temperature Intermetallic Phase (LTIP)-MnBi, as confirmed by scanning electron microscopy (SEM). Energy Dispersive Spectroscopy (EDS) elemental chemical composition analysis showed LTIP regions interspersed within Bi- and Mn-rich areas. Magnetic properties were determined by vibrating sample magnetometry (VSM), for which a considerable intrinsic coercivity field (iHc) up to 6000 Oe at 360 K, together with a saturation magnetization (Ms) of 57.49 emu/cm3. Therefore, this combination of properties renders LTIP is a promising precursor with potential for applications at high temperatures.

The use of nanostructured materials for enzyme immobilization is an active field of research due to its large surface area and the new emergent properties derived from its size. The present work is focused on the synthesis of magnetic nanoparticles for the adsorption of cysteine-proteolytic enzymes extracted from Bromelia antiacantha Bertol (Bromeliaceae) fruit. The results show that enzyme adsorption is highly dependent on the temperature and pH. The biocatalyst activity increased up to 40 %, once immobilized onto the magnetic nanoparticles. In addition, they can be recovered using a magnet allowing them to be reused up to 5 cycles with a marginal loss (5 %) of the initial activity.

Anomalous Hall effect was observed at room temperature in MOCVD-grown GaGdN from a (TMHD)3Gd source, which can contain oxygen in its organic ligand. GaN, and GaGdN grown using a Cp3Gd precursor which does not contain oxygen only showed the ordinary Hall effect. This indicates that oxygen could have a role in magnetic properties of GaGdN. The relationship between the anomalous Hall conductivity and longitudinal conductivity indicated that metallic conduction, hopping of carriers, and scattering-independent mechanisms are likely responsible for the ferromagnetism. However, this still requires further clarification.

This article provides a personal guided tour of multiferroic materials, from their early days as a theoretical curiosity, to their position today as a focus of worldwide research activity poised to impact technology. The article begins with the history of, and the answer to, the question of why so few magnetic ferroelectric multiferroics exist, then gives a survey of the mechanisms and materials that support such multiferroicity. After discussing the tremendous progress that has been made in the magnetoelectric control of magnetic properties using an electric field, some unusual applications of multiferroics in high-energy physics and cosmology are outlined. Finally, the most interesting open questions and future research directions are addressed.