Barium hexaferrite/muscovite heteroepitaxy with mechanically robust perpendicular magnetic anisotropy

Recent advances in the design and development of magnetic storage devices have led to an enormous interest in materials with perpendicular magnetic anisotropy (PMA) property. The past decade has witnessed a huge growth in the development of flexible devices such as displays, circuit boards, batteries, memories, etc. since they have gradually made an impact on people’s lives. Thus, the integration of PMA materials with flexible substrates can benefit the development of flexible magnetic devices. In this study, we developed a heteroepitaxy of BaFe12O19 (BaM)/muscovite which displays both mechanical flexibility and PMA property. The particular PMA property was characterized by vibrating sample magnetometer, magnetic force microscopy, and x-ray absorption spectroscopy. To quantify the PMA property of the system, the intrinsic magnetic anisotropy energy density of ~2.83 Merg cm−3 was obtained. Furthermore, the heterostructure exhibits robust PMA property against severe mechanical bending. The findings of this study on the BaM/muscovite heteroepitaxy have several important implications for research in next-generation flexible magnetic recording devices and actuators.

Thrust characteristics of compact high-voltage pulsed plasma thruster utilizing liquid propellant

In this work, we present the results on thrust performance of 0.5 kg sub-joule pulsed plasma thruster prototype based on a high-voltage transformer with magnetic storage capable of work at frequency of 400 Hz. The discharge unit is made of ferroelectric ceramics with an option for utilizing liquid propellant. In case of vacuum oil as a propellant, we obtained values of thrust of ~ 80 nN·s per discharge and 33 μN·s for 400 pulses in 1 second.

Synthesis, structure and electromagnetic properties of FeCoAl/C nanocomposites

Magnetic nanoparticles play an important role in rapidly developing advanced branches of science and industry, e.g. fabrication of magnetic storage media, synthesis of ferromagnetic liquids, medicine and chemistry. One problem faced in the usage of magnetic nanoparticles is their high chemical activity leading to oxidation in air and agglomeration. The chemical activity of magnetic nanoparticles stems from the contribution of their large specific surface to volume ratio. Carbon coating of nanoparticles reduces the interaction between nanoparticles. FeCoAl/C metal-carbon nanocomposites have been synthesized using IR pyrolysis of polymer/metal salt precursors. The effect of synthesis temperature (IR heating) in the range from 500 to 700 °C on the structure and composition of the nanomaterials has been studied. We show that the forming particles are the FeCoAl ternary solid solution with a FeCo based bcc lattice. An increase in the synthesis temperature from 500 to 700 °C leads to an increase in the coherent scattering region of three-component nanoparticles from 5 to 19 nm. An increase in the aluminum content from 20 to 30% relative to Fe and Co results in an increase in the size of the nanoparticles to 15 nm but this also entails the formation of a Co based solid solution having an fcc lattice. An increase in the nanocomposite synthesis temperature and a growth of the relative Al content as a result of a more complete carbonization and the structure-building effect of metals reduce the degree of amorphousness of the nanocomposite carbon matrix and lead to the formation of graphite-like phase crystallites having an ordered structure. The effect of synthesis temperature and relative content of metals on the electromagnetic properties (complex permittivity and permeability) of the synthesized nanocomposites has been studied. Synthesis conditions affect the radio absorption properties of the nanocomposites, e.g. reflection loss (RL) in the 3–13 GHz range.

Exchange Bias Effect in LaFeO3: La0.7Ca0.3MnO3 Composite Thin Films

Composite thin films arouse great interests owing to the multifunctionalities and heterointerface induced physical property tailoring. The exchange bias effect aroused from the ferromagnetic (FM)–antiferromagnetic (AFM) heterointerface is applicable in various applications such as magnetic storage. In this work, (LaFeO3)x:(La0.7Ca0.3MnO3)1−x composite thin films have been deposited via pulsed laser deposition (PLD) and the exchange bias effect was investigated. In such system, LaFeO3 (LFO) is an antiferromagnet while La0.7Ca0.3MnO3 (LCMO) is a ferromagnet, which results in the exchange bias interfacial coupling at the FM/AFM interface. The composition variation of the two phases could lead to the exchange bias field (HEB) tuning in the composite system. This work demonstrates a new composite thin film system with FM-AFM interfacial exchange coupling, which could be applied in various spintronic applications.

Current Progress of Magnetoresistance Sensors

Magnetoresistance (MR) is the variation of a material’s resistivity under the presence of external magnetic fields. Reading heads in hard disk drives (HDDs) are the most common applications of MR sensors. Since the discovery of giant magnetoresistance (GMR) in the 1980s and the application of GMR reading heads in the 1990s, the MR sensors lead to the rapid developments of the HDDs’ storage capacity. Nowadays, MR sensors are employed in magnetic storage, position sensing, current sensing, non-destructive monitoring, and biomedical sensing systems. MR sensors are used to transfer the variation of the target magnetic fields to other signals such as resistance change. This review illustrates the progress of developing nanoconstructed MR materials/structures. Meanwhile, it offers an overview of current trends regarding the applications of MR sensors. In addition, the challenges in designing/developing MR sensors with enhanced performance and cost-efficiency are discussed in this review.

Manipulation of Magnetization Reversal by Electric Field in a FePt/(011)PMN-PT/Au

Electric field manipulation of magnetism and 180° magnetization reversal are crucial for realizing magnetic storage devices with low-power consumption. Here, we demonstrate that electric-field manipulation of magnetic anisotropy rotation is achieved by the strain-mediated magnetoelectric effect in a Fe50Pt50/(011)0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3/Au. The remanent magnetization and magnetic coercivity of the Fe50Pt50 film exhibit an obvious response with the change of the electric fields. Moreover, the reversible in-plane 180° magnetization reversal can be controlled by alternating on or off the electric field under a small bias magnetic field. These results suggest a promising application for realizing magnetoelectric random access memory (MeRAM) devices with low-power consumption.

Minimization of the Electric Energy in Systems Using Ultra-High Density Magnetic Storage

We present an optimization of the thickness of the magnetic layers that serve to record the information of the daily need in order to minimize the useful electrical energy. The study provides details on the energy activation and distribution of the energy barriers in the samples of thickness . We find that distribution of the energy barriers , its distribution width , the real activation field are lowest in the sample of thickness , hence this sample allows to use less electrical energy for information recording.