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The very small and dense SDT memory cells arrays can be achieved with SDT memory cells in which the information is stored in the direction of the IrMn low blocking temperature. To demonstrate the durability and stability of the written IrMn antiferromagnetic pinning, a variety of test were conducted. For simplicity in fabrication, the test were conducted with just spin valve cells rather SDT cells...
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...
Exchange bias (EB) refers to the shift of the hysteresis loop, typically observed in exchange interacting ferromagnetic (FM)-antiferromagnetic (AFM) materials. During the last decades, EB properties have been extensively investigated, mainly in thin films, due to their technological applications in magnetic random access memories and magnetoresistive read heads based on spin valves or tunnel junctions...
This paper presents the first quantitative evaluation of the pinned uncompensated spin (UCS) density on the scale of single grains obtained from high lateral resolution magnetic force microscopy. All measurements presented were performed on one ferromagnetic-antiferromagnetic (FM/AFM) multilayer sample that contained a Co/Pt multilayer as ferromagnetic layer and CoO as an AFM layer. TEM of the CoO...
The formation of a parallel magnetic domain wall in the ferromagnetic (FM) Fe layer in Fe/FeF2 systems and antiferromagnetic (AF) FeF2 and MnF2 in Ni/FeF2 and Co/MnF2 bilayers as well as the magnetization reversal of uncompensated Fe interfacial moments in positively and negatively biased Ni/FeF2 was studied. Combining X-ray magnetic circular (XMCD) and linear dichroism (XMLD) measurements allows...
In the present study element specific magnetic hysteresis (ESMH) loops for Mn-Ir/Co-Fe bilayers with different chemical ordering of Mn-Ir layer by XMCD technique is determined.
In this study, PtMn nanoparticles were synthesized via a chemical method. After post-annealing at the temperature range of 500~700degC, different grain sizes were obtained. It was found the coercivity, measured at 5 K, decreased with increasing grain size. The exchange-bias was also observed at 5 K under a field-cooling process. The particle size and composition of as-synthesized PtMn nanoparticles...
In this paper, the antiferromagnetic (AF) NiMn exchange coupled-CoFe films exhibit excellent soft magnetic behaviors with very strong anisotropy at 90deg of the pinning direction is discussed. This led to very high ferromagnetic resonance frequency (FMR) up to 10 GHz with high permeability. These antiferromagnetic exchange coupled multilayers offer new and promising issues for magnetic microwave applications.
Phase-change memory devices, such as DVD media, have been growing rapidly due to their high capacity recording. The mechanism of the recording is based on the phase-change between the crystalline phase and the amorphous phase, and the two phases are recognized by the difference in their reflectivities. In analogy with such conventional phase-change memory materials, here a phase-change magnetic memory...
In this study, the formation of L12-Mn3Rh and L12-Mn3Ru phases were examined, in accordance with the recipe of L12-phase formation for Mn-Ir. The exchange biasing properties of the bilayers with these L12 phases were investigated.
This study investigates the exchange bias for Co2Cr0.6Fe0.4Al (CCFA) thin films epitaxially grown on MgO buffer layers. The CCFA/Ru/Co90Fe10 (CoFe) trilayers exchange biased with an IrMn layer through the CoFe/IrMn interface is investigated. Antiferromagnetic coupling was well established for all the CCFA/Ru/CoFe trilayers with tCCTA of between 2.5 and 4.0 nm and thus confirming that the CCFA/Ru/CoFe...
In this study, the growth of epitaxial (001) Co50Fe50/IrMn bilayers by using the epitaxial Cu underlayers on Si substrates, instead of the previously reported MgO substrates is demonstrated using dc magnetron sputtering. The highly conductive Cu underlayers can be used as bottom leads in magnetic tunneling junctions (MTJs). In addition, the anisotropy constants and the magnetization reversal mechanism...
The interaction of an antiferromagnet with a ferromagnet can establish a unidirectional anisotropy, which is referred to as an exchange bias. This paper presents a numerical simulations based on a simple coherent rotation model, which imply that the initial irreversibilities observed between the first and second hysteresis loop are driven by the symmetry of the antiferromagnet. The availability of...
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...
The double sintering ceramic technique is used in this study to synthesize the spinel oxide system, CuAlxCrxFe2-2xO4, with compositions x=0.0,0.2-0.8. The lattice constants of the ferrites show samples exhibiting single-phase spinel structures as determined by X-ray diffraction. Magnetic properties (e.g. hyperfine interactions, magnetic structure and cation distribution in the antiferromagnetically...
In this work, we report a study of the temperature dependence of magnetotransport properties for a series of [AF-LCMO (7.6nm)/F-LCMO (tF)]N superlattices. Superlattices of F-LCMO and AF-LCMO layers were grown on (001)-oriented SrTiO3 substrates via a high-pressure dc sputtering process. The modulation period have been experimentally derived from X-ray diffraction measurements, confirming that for...
In this paper, the potential for new device materials and insight into the effects of some of the different iron oxide forms on exchange bias with NiFe (Permalloy) was discussed. The iron-oxides have significantly different magnetic properties. Thin film bilayers were deposited using a dual ion-beam deposition technique that produced an antiferromagnetic iron-oxide layer composition that ranged from...
The authors study the effect of the interface on the coercivity Hc and the exchange field Hex in CoFe/IrMn systems by comparing the contribution of the interfacial area and the ferromagnetic layer thickness. It is shown that the exchange field only depends on the intrinsic coupling at the interface and thermal effects. By increasing activation temperature TACT, the amount of antiferromagnetic material...
In this study the exchange anisotropies of (001) oriented Mn1-xPtx/NiFe epitaxial bilayers were investigated, and found that the bilayer exhibit both strong 1-and 4-fold anisotropies, which was hard to be understood by a simple single spin model. Thus, XMCD (X-ray magnetic circular dichroism) measurements has been carried out to insight the magnetism of Mn and Fe or Co at the interface of Ni80Fe20...
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