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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...
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...
New bio-detection methods based on giant magnetoresistance (GMR) or tunneling magnetoresis-tance (TMR) sensors and magnetic nanoparticles are attracting much attention due to their high sensitivity and low cost. In literature, signal to noise ratio (SNR) is often used to estimate detection limit. However, because the actual bio-signal is obtained by differentiating signals before and after biological...
All-metallic giant magnetoresistive (GMR) sensors in a current-perpendicular-to-plane (CPP) geometry are attractive candidates for future high-density recording sensors due to their low intrinsic resistance. With increasing recording density the cross-sectional area of CPP sensors (such as TMR or GMR sensors) must also decrease, resulting in a rapid increase in sensor impedance unless the RA product...
This article presents experiments on the magnetic characterisation of quaternary Heusler alloys for spintronic applications. In this work, polycrystalline Co2Cr1-XFeXAl (CCFA), Co2Cr1-XVXAl (CCVA) and Co2V1-XFeXAl (CVFA) bulk alloys were prepared by arc melting for mictrostructural, magnetic, and spin polarised properties. Magnetic measurements were carried out using VSM and SQUID magnetometry. Material...
We have fabricated tunnelling magnetoresistance (TMR) devices based on an epitaxial layer of NiMnSb grown almost lattice matched on (In,Ga)As, an aluminium oxide barrier and a CoFe counter electrode. The devices show a TMR of 14% at low temperature and 8% at room temperature. The as-grown NiMnSb layer exhibits a strong uniaxial anisotropy, which leads either to a clean spin valve signal with layers...
Tunneling magnetoresistive (TMR) head are promising device for high storage density of 100 Gbit/in magnetic recording head. Structure of TMR recording head is different from typical giant magnetoresistive (GMR) spin-valve read head. It is essential to understand the electrostatic discharge (ESD) effect on TMR device behavior and its impacts on device characterization. In this paper, we reported several...
The behavior of spiral flow structures along the trailing edges of the E-block arm has been investigated under increasing airflow velocities. These coherent structures in the flow are commonly believed to be closely associated with the flow induced vibrations on the E-block arms. The experiments showed that vortex shedding is detected in a HDD model when the motor speed is as low as 1200 rpm. A turbulent...
The use of tunneling magneto-resistive (TuMR) head, at low temperature, has bad read/write characteristics for the disk regions with high data transfer rate. To prevent the bit error rates (BERs) degradation at low temperature, a solution which can quickly increase temperature more than specific value is proposed. A random seeking method with heater is operated to rapidly increase the rising speed...
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...
The authors study the dielectric breakdown (DB) in low resistance, underoxidized Mnlr/CoFe/AlOx/CoFe magnetic tunnel junctions (MTJs) and show that the breakdown occurred at localized spots of the barrier where large concentration of oxygen vacancies exist. They also show the dependence of the tunneling magnetoresistance (TMR) on the applied current of a 1x1 mum2 MTJ with (30 s)+(30 s)+5 oxidation...
Orange-peel coupling (OPC) is a common problem when magnetic tunnel junctions (MTJs) are used to detect low magnetic fields. OPC acts as an anisotropy field to reduce the sensitivity of the free layer to small magnetic fields. We have have found that pre-oxidation of the bottom Co electrode in MJTs very effectively suppresses OPC.
This paper investigates the relationship between the tunneling magnetoresistance (TMR) ratio and the structure of MgO-based MTJs with crystallized CoFeB layers by annealing having CoFe/Ru/CoFeB synthetic ferrimagnet (SF) pin layers with varying Ru spacer thicknesses (tRu). When annealing temperature Ta is lower than 325degC, the Ta dependences of the TMR ratio are similar among all the MTJs. However,...
In this paper, we have fabricated and studied the bias dependence of magnetic tunnel junctions based on a CoFeB / MgO / CoFeB tri-layer structure. These structures exhibit TMR ratios as high as 236% at room temperature. Furthermore, we have observes a weakened dependence of TMR on bias voltage in these structures, with the MR ratio decaying to one half of the zero-bias value at an applied voltage...
This paper aims to investigate the magnetic and electrical properties of magnetic tunnel junctions with MgO barriers. The magnetoresistance of the junction is measured at 0.4 V. Results show a magnetoresistance of almost the same values at varying radical oxidation time and Mg thickness. It is also confirmed in this study that the MgO formed by radical oxidation of Mg shows high magnetoresistance...
Both theoretical and experimental studies of the epitaxial Fe/MgO/Fe(001) trilayers have shown new spin dependent tunnelling processes due to the conservation of the (001) crystallo-graphic orientation in the entire stack. In addition the MgO barrier acts as a spin filter : the tunnelling electrons are more or less attenuated in the barrier as a function of their symmetry. The very high tunneling...
This article discusses the TMR, tunneling resistance, and I-V characteristic in FeCo/MgO/FeCo MTJs with various FeCo/MgO interface state by using wedged-film deposition technique.
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