Interlayer coupling in Co/Os multilayers

doi:10.1016/0304-8853(93)91209-P

Journal of Magnetism and Magnetic Materials

Volume 121, Issues 1–3, 2 March 1993, Pages 306-308

https://doi.org/10.1016/0304-8853(93)91209-P Get rights and content

Abstract

Antiferromagnetic interlayer coupling is determined from hysteresis loop measurements for Co/Os multilayers with Os thickness varying from 4 to 36Å. We found two maxima of antiferromagnetic coupling, which is consistent with an oscillatory behavior with a period of approximately 15Å: this is significantly larger than the period observed for interlayers of Ru, which has a very similar band structure and a topologically equivalent Fermi surface.

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Cited by (8)

Interlayer exchange coupling in multilayered Co/Os
2012, Journal of Magnetism and Magnetic Materials
Citation Excerpt :
It has been shown that the measured oscillation period of IEC in a Co/Os multilayer was 15 Å [7], which is unique in 3d, 4d and 5d transition metals, where the general trend for oscillation periods is in the range 9–12 Å [41,42]. For this reason we use both the QW model and RKKY theory in addition to ab-initio total energy calculation to study the IEC in Co/Os multilayer and trilayer to confirm our finding about the presence of the short period oscillation in Os with 9–10 Å in addition to the long one of 15 Å which is detected experimentally [7]. According to the Phase Accumulation Model (PAM) we can predict the energy for QW states [43].
We have studied the interlayer exchange coupling (IEC) in Co/Os_n/Co in trilayer geometry using the quantum well (QW) model, RKKY theory in the framework of ab-initio total energy calculation. Also we have used the phase accumulation model (PAM) to describe the thickness dependence of QW states energies. We predict the presence of a short period oscillation in Os with 3.5–4 ML in addition to the long one of 7 ML which has been measured experimentally. Our results of PAM relate the oscillation periods of 6.29 ML and 3.69 ML to $\bar{Γ} (k_{| |} = 0)$ and $\bar{M} (k_{| |} \neq 0)$ direction, respectively. On the other hand, using our calculated Fermi surface including spin–orbit coupling of bulk Os we identified the two periods as the spanning vectors at $Γ$ -centered nested electron surfaces e₉, 6.86 ML for long period, and inner hole ellipsoid h₇, 3.80 ML for short period. These periods are very comparable to those periods of 6.8 ML and 3.7 ML obtained by RKKY-fitting of the IEC. The principal behavior of the IEC found experimentally is reproduced by the theory. We have found in our calculations of IEC in the multilayer geometry Co_m/Os_n a shift of the AF coupling peaks when we varied the thickness of the FM layers which might be interpreted as due to QW interactions.
Chapter 1 GMR in Metallic Multilayers - A Simple Picture
2008, Handbook of Metal Physics
The basic physics related to the giant magnetoresistance (GMR) effect is tied to the fact that the electron spin takes two different values (say up and down) and, when traveling through magnetized materials, one type of spin might encounter a resistance that is different from that experienced by the other. Thin metallic multilayers became the proving ground for the GMR effect because their magnetizations could be altered with some ease, especially in a sandwich structure. In this chapter, details can be found about the GMR effect, its discovery and history, magnetic recording as well as other related phenomena. This chapter discusses magnetoresistance, magnetic recording, perpendicular recording and future storage technology, and a historical perspective of GMR. There is a discussion about qualitative arguments including quantum well (QW) approach and spin-polarized quantum well states. There is discussion on growth related issues and measuring interlayer coupling, GMR in magnetic sensors, biquadratic coupling. The chapter also discusses selected multilayer systems—Co/Cu (001), multilayers grown on Fe whiskers, Fe/Cr system, multilayered alloys, and nanowires. There are details on scattering of electrons, magnetic tunnel junctions, and half-metallic systems. An introduction to the GMR effect has been provided. Some applications, such as magnetic recording, sensors, and multilayered nanowires are discussed briefly and with vivid examples. A picture of how the magnetic exchange interaction gets transmitted through the spacer layer is provided using quantum well ideas from elementary quantum mechanics. In addition, various related experimental systems are discussed and compared to theoretical calculations.
Chapter 1 Interlayer exchange coupling in layered magnetic structures
2001, Handbook of Magnetic Materials
Since the discovery of antiferromagnetic type interlayer coupling between two ferromagnetic layers across a non-ferromagnetic spacer layer in 1986 numerous sample systems with many different material combinations and structural properties have been investigated. Here we give a critical review of the research on coupling phenomena. Sample preparation and measurement techniques will be discussed as well as physical pictures that allow a theoretical description of bilinear and biquadratic coupling. Experimental results are presented with emphasis on the dependence of the coupling on the nature of the interlayer material.
Interlayer exchange coupling
1999, Journal of Magnetism and Magnetic Materials
The extensive research done on interlayer exchange coupling in transition metal multilayers has resulted in a deep understanding of this coupling and a remarkable agreement between theoretical results and measurements. The coupling between two magnetic layers separated by a non-magnetic spacer layer is mediated by the electrons of the spacer layer. The coupling, which oscillates in sign as a function of the thickness of the spacer layer, is closely related to the well-known RKKY interaction between magnetic impurities. Due to the existence of many high-quality measurements, it has been much more fully developed theoretically than the interaction between impurities. Theory predicts that the periods of the oscillatory coupling should depend on critical spanning vectors of the Fermi surface belonging to the spacer-layer material. There is remarkable agreement for the measured periods and those predicted from the Fermi surfaces. There is also substantial agreement between theory and experiment on the strength of the coupling. This review presents the comparison between theory and experiment in some detail.
Interlayer exchange coupling
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Interlayer exchange coupling and giant magnetoresistance in magnetic multilayers
1996, Acta Physica Polonica A

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Interlayer coupling in Co/Os multilayers

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