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T Yang - One of the best experts on this subject based on the ideXlab platform.
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A study of Exchange Coupling in NIFE/NIMN bilayers
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2000Co-Authors: T Yang, Chunlin ChaiAbstract:The effects of annealing time and temperature on the Exchange Coupling between ferromagnetic (FM) NiFe and antiferromagnetic (AFM) NiMn layers prepared by magnetron sputtering were systematically studied. With both increasing annealing temperature and annealing time, the interfacial Exchange Coupling energy J(ex) showed an initial increase followed by a decrease. Magnetic measurement and X-ray diffraction (XRD) analysis revealed that the evolution of J(ex) should be attributed to the competing of paramagnetic (PM)-AFM phase transition and the interdiffusion across the interfaces caused by annealing. It can be deduced that overannealing, including both too long annealing time and too high annealing temperature, is detrimental to the interfacial Exchange Coupling. It was also shown that the Exchange Coupling between NiFe and NiMn layers was thermally very stable. PACS: 75.50 (C) 2000 Elsevier Science S.A. All rights reserved.
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Exchange Coupling and thermostability in NiFe/NiMn bilayers
Journal of Physics D, 1999Co-Authors: T YangAbstract:The effects of annealing time and temperature on the Exchange Coupling between ferromagnetic NiFe and antiferromagnetic NiMn layers prepared by magnetron sputtering were systematically studied. With both increasing annealing temperature and annealing time, the Exchange Coupling energy Jex, derived from Exchange Coupling field Hex and saturation magnetization MS, showed an initial increase followed by a decrease. Due to the reduction of MS resulting from the interdiffusion across the interfaces during annealing, there is a slight difference between the way Jex varies with annealing temperature and annealing time and the way Hex varies. From the evolution of Jex, it can be deduced that over annealing, including both annealing for too long time and at too high a temperature, is detrimental to the interfacial Exchange Coupling. The Exchange Coupling between NiFe and NiMn layers was very stable within an environmental temperature ranging from room temperature to about 210 °C. The Exchange path was checked and the distribution of blocking temperature Tb was estimated.
Hiroaki Muraoka - One of the best experts on this subject based on the ideXlab platform.
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Optimizing Dual-Layer Recording Using Antiferromagnetic Exchange Coupling
IEEE Transactions on Magnetics, 2018Co-Authors: Simon John Greaves, Tadahiro Kikuchi, Yasushi Kanai, Hiroaki MuraokaAbstract:Selective recording on media with two discrete recording layers is complicated by magnetostatic interactions between the layers. Introducing antiferromagnetic Exchange Coupling can compensate for these interactions to some extent. This paper investigates the effect of the antiferromagnetic Exchange Coupling strength in a dual-layer medium and shows that the recording performance can be improved when the antiferromagnetic Exchange Coupling is optimized.
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SNR improvement by intergranular Exchange Coupling in CGC perpendicular magnetic recording media
Journal of Magnetism and Magnetic Materials, 2008Co-Authors: J. Yasumori, Hiroaki Muraoka, Katsuya Miura, Yoshiaki Sonobe, Koichi WagoAbstract:Effect of intergranular Exchange Coupling in coupled granular and continuous (CGC) perpendicular media was investigated in terms of improvement of signal-to-noise ratio (SNR). The Exchange Coupling improves SNR and byte error rate (BER); however, it tended to widen the magnetic track width (MWW) of a track. That degradation is of concern for the CGC media. This paper discusses intergranular Exchange Coupling in CGC media to optimize track density and linear density to achieve high areal density.
C. A. R. Sá De Melo - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Exchange Coupling through superconductors: A trilayer study
Physical Review B, 2000Co-Authors: C. A. R. Sá De MeloAbstract:The possibility of magnetic Exchange Coupling between two ferromagnets (F) separated by a superconductor (S) spacer is analyzed using the functional integral method. For this Coupling to occur three prima facie conditions need to be satisfied. First, an indirect Exchange Coupling between the ferromagnets must exist when the superconductor is in its normal state. Second, superconductivity must not be destroyed due to the proximity to ferromagnetic boundaries. Third, roughness of the F/S interfaces must be small. Under these conditions, when the superconductor is cooled to below its critical temperature, the magnetic Coupling changes. The appearance of the superconducting gap introduces a new length scale (the coherence length of the superconductor) and modifies the temperature dependence of the indirect Exchange Coupling existent in the normal state. The magnetic Coupling is oscillatory both above and below the critical temperature of the superconductor, as well as strongly temperature-dependent. However, at low temperatures the indirect Exchange Coupling decay length is controlled by the coherence length of the superconductor, while at temperatures close to and above the critical temperature of the superconductor the magnetic Coupling decay length is controlled by the thermal length.
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MAGNETIC Exchange Coupling IN FERROMAGNET/SUPERCONDUCTOR/FERROMAGNET MULTILAYERS
Physical Review Letters, 1997Co-Authors: C. A. R. Sá De MeloAbstract:The possibility of magnetic Exchange Coupling between two ferromagnets ({ital F}) separated by a superconductor ({ital S}) spacer is analyzed using the functional integral method. For this Coupling to happen three basic conditions need to be satisfied. First, an indirect Exchange Coupling between the ferromagnets must exist when the superconductor is in its normal state. Second, superconductivity must not be destroyed due to the proximity to ferromagnetic boundaries. Third, roughness of the F/S interfaces must be small. The appearance of the superconducting gap causes a reduction of the indirect Exchange Coupling existent in the normal state. This reduction is temperature dependent, being weaker near the critical temperature and stronger at zero temperature. {copyright} {ital 1997} {ital The American Physical Society}
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Magnetic Exchange Coupling through a superconductor
Journal of Applied Physics, 1997Co-Authors: C. A. R. Sá De MeloAbstract:The magnetic Exchange Coupling between two ferromagnets separated by a superconducting spacer is analyzed. An indirect Exchange Coupling between the ferromagnets is assumed to exist when the superconductor is in its normal state. As the superconductor is cooled off below its critical temperature, the magnetic Coupling changes. The appearance of the superconducting gap causes a reduction of the indirect Exchange Coupling existent in the normal state. This reduction occurs within a length scale controlled by the coherence length of the superconductor. The reduction of the Coupling is temperature dependent, being weaker near the critical temperature and stronger at zero temperature. In addition, the change in critical temperature of the superconductor due to proximity to ferromagnets is discussed.
B. Lengsfield - One of the best experts on this subject based on the ideXlab platform.
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Exchange Coupling optimization on CoPtCrO perpendicular media
2003 IEEE International Magnetics Conference (INTERMAG), 2003Co-Authors: Y. Ikeda, K. Takano, N. Supper, Hao Do, Y. Sonobe, B. LengsfieldAbstract:In this paper, medium noise and Exchange Coupling correlation have been investigated by changing the oxygen ratio in the sputter gas. To determine the amount of intergranular Exchange Coupling in this media, the experimental results were modeled using numerical simulation.
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Exchange Coupling optimization on CoPtCrO perpendicular media
IEEE Transactions on Magnetics, 2003Co-Authors: Y. Ikeda, K. Takano, N. Supper, Hoa Do, B. LengsfieldAbstract:CoPtCrO is an ideal system to study the influence of Exchange on the performance of granular perpendicular media. By changing the oxygen ratio during the deposition process, loop shape and thus inter-granular Exchange can be controlled. Noise measurements show there is an optimum Exchange Coupling which reduces the total media noise in the system. Numerical simulations using the experimental media parameters were found to reproduce the measured loop shapes and noise behavior. The optimization of Exchange Coupling was found to be a key factor in the design of low noise CoPtCrO perpendicular media.
Hartmut Zabel - One of the best experts on this subject based on the ideXlab platform.
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Tunability of the interlayer Exchange Coupling
Journal of Physics D, 2002Co-Authors: V. Leiner, Kurt Westerholt, Björgvin Hjörvarsson, Hartmut ZabelAbstract:The effect of the interlayer Exchange Coupling on the ordering temperature of ultrathin magnetic layers has been explored for two systems: Ho/Y and Fe/V superlattices. In both cases, the Exchange Coupling can be modified and eventually removed by the introduction of hydrogen into the mediating non-magnetic spacer layer. In case of Ho/Y we observed a drastic drop of the Ho Neel temperature from 105 K for coupled Ho blocks of 10 monolayer thickness to 65 K for isolated or uncoupled Ho blocks. In Fe/V superlattices, the incorporation of hydrogen changes the strength and sign of the Exchange Coupling constant. Again, we observed that the ordering temperature clearly depends on the strength of the Exchange Coupling in both the antiferromagnetically and the ferromagnetically coupled range of the phase diagram.
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Exchange Coupling in magnetic superlattices
Third International Conference on Thin Film Physics and Applications, 1998Co-Authors: Hartmut ZabelAbstract:Artificial magnetic superlattices composed of successive ferromagnetic and paramagnetic layers have received much attention in recent years due to their scientific and technological relevance. While the strength of the Exchange Coupling and the oscillation period depend on the details of the Fermi surfaces involved, the overall features appear universal. More complex Couplings are observed for magnetic superlattices with chromium spacer layer. This is due to the intrinsic spin density wave of Cr. Extensive synchrotron and neutron scattering experiments have now unraveled the Neel- state of thin Cr layers and proximity effects between Fe and Cr, elucidating the mutual interdependence of Cr spin structure and Fe Exchange Coupling. In Co/Cr superlattices the structural mismatch between hcp Co and bcc Cr adds another complexity, which affects strongly the magnetic anisotropy. Both, the current status and understanding of the Exchange Coupling in Fe/Cr(001) and Co/Cr(001) superlattices is briefly reviewed here.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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Oscillatory Exchange Coupling in Co/Cu(111) superlattices.
Physical Review B, 1993Co-Authors: A. Schreyer, K. Bröhl, J. F. Ankner, Charles F. Majkrzak, Th. Zeidler, P. Bödeker, Naoto Metoki, Hartmut ZabelAbstract:By probing the magnetisation profile of high-quality molecular-beam-epitaxy-grown Co/Cu(111) superlattices with spin-polarised neutron reflectivity (SPNR), we have observed a coherent antiferromagnetic spin structure and confirm that this Coupling behavior sensitively depends on the Cu sparer thicknesses. We present magneto-optical Kerr-effect data from which the oscillation period of the Exchange Coupling can be determined to be about 9 A, consistent with theory and the SPNR data. With these results we confirm the existence of an oscillatory Exchange Coupling in this controversial system
