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The current-driven magnetization switching in CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) with various free layer materials including synthetic structure was studied in this paper. The MTJ films were deposited on SiO2/Si substrates using RF magnetron sputtering. The tunnel magnetoresistance (TMR) ratios and current-voltage (I-V) characteristics of the the MTJs were measured at room temperature...
A detailed characterization and analysis of the microwave properties of a set of nanogranular (Fe0.7Co0.3)71B22Ni7 films under an applied magnetic dc field ranging from 0 to 45 kA/m is presented. A full microwave characterization of the films is performed up to 20 GHz using a vector network analyzer (VNA) connected to a matched microstripline or coplanar waveguide, loaded with the films. The evolution...
The domain wall dynamics during magnetization reversal process of glass-coated amorphous Fe77.5Si7.5B15 bistable microwire was considered. Its domain structure deriving from the magnetoelastic and shape anisotropies consists of an axial single domain and two closure domain structures at the ends, plus an outer radial-helical shell in its surface. This articles report the measured domain wall velocities,...
Amorphous Fe73.5Cu1Nb3Si15.5B7 ribbons that are 2 mm wide and 20 mum thick were prepared by the continuous stress annealing-Joule heating (CSA-JH) method in air under tensile stresses of 50 to 175 MPa. Processing parameters such as the supplied current density and the moving velocity were varied. The ribbons were annealed at various conditions, and the relationship between the developed anisotropy...
The aim of this paper is to investigate FeCuSiBNb nanocrystalline microwires as an alternative to amorphous Co-based high-permeability microwires. The anisotropy is determined through static characterization from 20degC to 250degC using a VSM (Vibrating Sample Magnetometer). The properties are comparable in term of softness, but are superior in terms of saturation magnetostriction and thermal stability...
In this study, we investigated that both magnetic switching and tunneling magnetoresistance (TMR) ratio of MTJs with the NiFeSiB free layer. The junctions were fabricated by a photolithographic patterning procedure and ion beam etching. A magnetic field of 100 Oe was applied during deposition to induce the uniaxial magnetic anisotropy in ferromagnetic layer.The NiFeSiB layers were used to substitute...
Summary form only given. This paper focuses on the possibility of direct casting miniature NdFeB-based bulk permanent magnets in different three-dimensional shapes for various applications, with amorphous structure followed by subsequent optimal annealing. Nd3Dy1Fe66Co10B20 bulk nanocomposite permanent magnets in form of rods with diameters ranging from 0.5 to 0.8 mm have been prepared by devitrification...
Thick NdFeB films have been prepared by triode sputtering with a deposition rate of 20 mum/hour. Films were deposited on either "cool" substrates or onto substrates heated in the range 300-500degC and then annealed at 750degC for 10 minutes. Magnetic characterisation was carried out at room temperature with an extraction magnetometer in fields of up to 10 T. Microstructures were observed...
In this paper, the microstructure and magnetic properties of the Fe3B/(Pr,Tb)2Fe14B nanocomposite permanent magnets obtained from melt-spun powders with composition of Pr4.2Tb0.3Fe78B17.5 by applying spark plasma sintering (SPS) was discussed. Since the magnetic properties such as remanence (Br) and coercivity (Hci) will deteriorate dramatically due to excessive grain growth during sintering process...
In this report, the magnetic microstructures of the melt-spun(Fe0.55Pt0.45)78Zr2B20 and (Fe0.55Pt0.45)78Zr4B18 in as-quenched state were investigated by Lorentz microscopy and electron holography. The in-plane component of the magnetic flux was visualized by analyzing the phase shift of the electrons traversing the specimen by using the Fourier transform for digital holograms. An ex situ observation...
For toggle MRAM, the free layer is a synthetic antiferromagnet (SAF) that must have specific magnetic properties such as: low magnetostriction, a repeatable saturation field (Hsat) that can be adjusted within a specific range, and a well-defined and reproducible intrinsic anisotropy axis. The results from fully-functional Mb-scale MRAM circuits using CoFeB SAF free layers optimized for toggle switching...
In this paper, the authors have reported a new directional coupler for the cellular phones with an operating frequency of 0.8-2 GHz, which consisted of a coupled microstrip structure with an amorphous CoFeB magnetic thin film and a polyimide dielectric film.
FeCuNbSiB amorphous microwires with average diameter about 40 mum were fabricated by a specially designed melted quench facility. Anneal treatment at T=673K for 1 hour had been carried out for amorphous wires to obtain nanocrystalline grains with average grain diameter of 34 nm. Then, the heat treated microwires were cut into short fibers, the length and diameter ratio was about 2. The composite samples...
The soft under layer (SUL) is used to improve write head filed strength, field gradient and read-back signal in perpendicular magnetic media. In this study, four type SUL structures were fabricated. Samples were post-annealed and cooled to room temperature under magnetic field along radial direction. VSM, MFM and Guzik spin stand were used to analyze the magnetic properties, domain structure and noise...
In this work, we fabricated multi-component pseudobinary TbxDy0.7-xPr0.3(Fe0.9B0.1)1.93 system and their epoxy-bonded composites and their magnetic hysteresis loops and magnetostrictive properties for x varying within the anisotropy minimization region of 0.16-0.25 was studied.
A cantilevered actuator is fabricated in this study by sputter deposition using amorphous Fe72Si14B14 as the magnetostrictive material. The displacement of the cantilever is observed with applying the magnetic field of 10 kA/m to the width direction of the cantilever. Results show that the displacement of the cantilever increased with decreasing substrate thickness, and has a peak value at the thickness...
In this study, we investigated the TMR effects in CoFeB/MgO/Heusler alloys (Co2FeSi and Co2MnSi) magnetic tunnel junctions. Both Co2FeSi and Co2MnSi heusler alloys have half-metallic band structure and high Curie temperature of 1200K and 985K, respectively. Moreover, the lattice mismatch between the Heusler alloys and MgO barrier is relatively small, which indicates that the highly textured Heusler...
In this report, we will demonstrate that by simply using a bilayer capping layer of Ru/Ta instead of usually used Ta, the switching field, as well as distribution of switching fields, of magnetic tunnel junctions (MTJ) can be considerably reduced. Two samples with the same MTJ stack of Ta/PtMn/SAF-pinned/AlOx/CoFeB(2 nm) (bottom to top) but capped by different metal layers of Ta and Ru/Ta, correspondingly,...
Increasing the frequency of electro-magnetic devices has been continuously pushing magnetic materials to operate over several GHz ranges.The permeability measurement of magnetic thin films were performed by both a broadband CPW and a network analyzer (0.1 -20 GHz) and Ryowa permeameter based on a single turn strip loop. The CPW was designed to have near 50Omega impedance, matching the network analyzer...
Amorphous and nanocrystalline Fe-based alloys are technologically important materials due to their good magnetic properties and low cost. However, the appearances of the alloys obtained by melt spinning and sputtering techniques are limited to ribbon and strip, film, wire, and powders, which largely restricts their applications in many engineering devices in which big size and arbitrary shape are...
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