Paving Spin-Wave Fibers in Magnonic Nanocircuits Using Spin-Orbit Torque

published_or_final_versio

A Novel Bar-Shaped Magnetic Shielding for Magnetoresistive Sensors in Current Measurement on Printed Circuit Boards

Session PF: Materials for Applications, abstract no. PF-02This paper presents the study of a novel bar-shaped magnetic shielding for magnetoresistive (MR) sensors in current measurement on printed circuit boards (PCB). The main physical principles of the shielding effect were studied by using the analytical model of magnetic flux concentration. Finite element analysis (FEA) simulations were used to simulate the shielding effects with changing geometrical parameters of the bar-shaped magnetic shielding. The dependences of the shielding effect on the parameters of length, width and thickness were analyzed. It shows that these parameters are critical for designing magnetic shielding. This new concept of magnetic shielding for MR sensors in current measurement on PCB was experimentally tested and verified in a laboratory setup. The experimental results verify the feasibility and effect of this novel magnetic shielding for MR sensors.published_or_final_versio

Performance Optimization of Spin-Torque Microwave Detectors with Material and Operational Parameters

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Skyrmion Domain Wall Collision and Domain Wall-Gated Skyrmion Logic

preprin

Effect of synthesis conditions on the physiochemical properties of lauric acid coated magnetite nanoparticles

Magnetic iron oxide nanoparticles have attracted broad interests in many biomedical areas, such as magnetic resonance imaging (MRI) contrast enhancement, magnetic hyperthermia, magnetic bio-sensing, and cell labeling [1]. To avoid nanoparticle aggregation and enhance their colloidal stability, carboxylate surfactants are widely used as coating materials to form steric repulsions between nanoparticles [2]. Lauric acid is one of the classical carboxylate materials, and is already approved for use in pharmaceuticals and food industry, which makes it a very promising coating material for nanoparticles in biomedical application. [3] Various methods, like mechanical milling, microemulsion, co-precipitation, thermal decomposition, etc., have been widely attempted to prepare nanoparticles. However, it is reported that the synthesis route has great impact on the properties of nanoparticle products, such as aluminium oxide nanoparticles, cobalt ferrite nanoparticles, and so on [4, 5]. Therefore, it is worthwhile to investigate the effects of different synthesis methods on the properties of lauric acid coated magnetic iron oxide nanoparticles. The research outcome can enable the synthesis of magnetic nanoparticles with desired features. Here, lauric acid coated iron oxide nanoparticles (LAIONPs) were prepared through two methods, co-precipitation and thermal decomposition. The products were characterized by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), dynamic light scattering (DLS), thermo gravimetric analysis (TGA), and vibrating sample magnetometry (VSM). The iron-oxide-core average size could be tuned from 9 nm (CP-1), 11 nm (CP-2) to 13 nm (CP-3) by using different stirring speed of 1200 rpm, 800 rpm, and 400 rpm, respectively in co-precipitation experiments, while the core average size could be adjusted from 7 nm (TD-1), 11 nm (TD-2) to 17 nm (TD-3) by following different heating process in thermal - ecomposition experiments. (Fig. 1) The nanoparticles obtained through thermal decomposition (LAIONPs-TD) showed more uniform sizes and morphologies than the ones got from co-precipitation (LAIONPs-CP). Higher mass ratio of lauric acid in TD samples than CP samples, as indicated in TGA results (Fig. 2a and 2b), implies higher surface cover density of lauric acid surfactant on LAIONPs-TD than LAIONPs-CP. All the six LAIONPs samples exhibited superparamagnetic behavior at room temperature (Fig. 2c and 2d). The saturated magnetization (Ms) of LAIONPs increased as the particle size increased. Such a trend can be observed in the samples obtained through co-precipitation (CP-1, 54 emu/g; CP-2, 58 emu/g; and CP-3, 63 emu/g) and also in the samples obtained through thermal decomposition (TD-1, 53 emu/g; TD-2, 64 emu/g; TD-3, and 78 emu/g). For the LAIONPs with similar average core size of 11 nm, Ms value of TD-2 obtained by thermal decomposition (64 emu/g) was higher than CP-2 obtained by co-precipitation (58 emu/g). As shown in Fig. 2e, in colloidal solution with solvent of chloroform, smaller mean hydrodynamic sizes and narrower hydrodynamic size distributions were observed on IONPs-TD samples, compared with IONPs-CP samples. This work revealed the influences of two different synthesis methods on the core size, morphology, hydrodynamic size, surfactant coating mass ratio, and magnetic behavior of the final products. Our comparative study provides insights into the influence of synthesis conditions on the geometrical and magnetic properties of lauric acid coated iron oxide nanoparticles.postprin

A Novel Approach for Fault Location of Overhead Transmission Line with Non-Contact Magnetic Field Measurement

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Broadband point measurement of transient magnetic interference in substations with magnetoresistive sensors

This journal issue contain selected papers from the Asia-Pacific Data Storage Conference (APDSC'13)Electromagnetic interference (EMI) in substations can be an obstacle for the development of the Smart Grid. This challenge is particularly critical since more and more secondary systems are transferred from control rooms to switching yards in modern power systems. Thus, it is important to develop a tool that can properly characterize and evaluate the EMI level. This paper introduces a novel broadband point measurement technology for evaluating the effect of transient magnetic field (TMF) on secondary systems in substations. The received disturbance level is defined for the victim circuit and the evaluation approach is proposed. The effect of sensor size on the measurement of TMF is explained and illustrated with numerical simulation, indicating the importance of point measurement. The designed measurement system was tested and the TMF caused by charging traveling wave in a 110-kV substation was characterized. Our results show that the TMF may produce significant effect on the secondary systems in a substation, and thus it is important to have the capability to evaluate the interference level.published_or_final_versio

Injection locking of spin-torque nano-oscillators

This journal issue contain selected papers from the Asia-Pacific Data Storage Conference (APDSC'13)We demonstrated the phase locking of a spin-torque oscillator (STO) to an alternating current (ac) using macrospin and micromagnetic simulations. We found that the locking properties of both approaches agree with each other. The phase difference between the STO and the injected ac stabilizes at ∆φ ≈ 90° and is not sensitive to the initial phase difference, which provides potential application of STO for microwave generation.published_or_final_versio

Magnetism in clean energy and environment

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Overhead High-Voltage Transmission-Line Current Monitoring by Magnetoresistive Sensors and Current Source Reconstruction at Transmission Tower

Session PF: Materials for ApplicationsThis paper proposes a novel current monitoring technology based on magnetic field sensing at a transmission tower for overhead high-voltage transmission lines (HVTLs), which can accurately measure phase current parameters in real time. This technology is based on the phenomenon that the magnetic field distribution at the top level of a transmission tower can reflect the operation states of the transmission lines including current amplitude and phase angle imbalances. A current source reconstruction method based on stochastic optimization strategy was developed to reconstruct the electrical parameters from the magnetic field emanated by the overhead transmission lines. This concept of current monitoring by magnetic field sensing and current source reconstruction was experimentally implemented and verified in our laboratory setup. A typical model of 500 kV three-phase transmission lines was simulated to further corroborate this technology. The reconstruction results for the 500 kV transmission lines verify the feasibility and practicality of this novel current monitoring technology based on magnetic field sensing at the top of a transmission tower for monitoring overhead transmission lines.published_or_final_versio