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Major hysteresis loops of the F/NM/F/AF structure are classified according to the magnetization process, with the assumption of coherent rotation for each F component and antiferromagnetic coupling between the two F layers. Magnetic stable states of the system as well as specific reversal modes of magnetization during each stage of the major hysteresis cycle are studied in detail based on energetics analysis, in the whole range of exchange bias field and interlayer antiferromagnetic coupling strength. The analysis shows 12 different types of major hysteresis loops for this system and is confirmed by simulation. Strategies to determine key material parameters for the F/NM/F/AF structure from major hysteresis loops are proposed and illustrated by numerical simulation. The research shows a subtle tuning of the magnetization process in the F/NM/F/AF structure, collectively by exchange biasing and interlayer antiferromagnetic coupling. Practically, this serves as a theoretical grounding for the identification of root causes of failure in the product analysis of GMR (giant magnetoresistance) sensors. [ABSTRACT FROM AUTHOR]

A very thin Cu (~1 nm) buffer layer on Si(110) is enough to induce [Ni.sub.80][Fe.sub.20]/[Fe.sub.60][Mn.sub.40] (111) epitaxial growth. The film surface roughness increases with increasing Cu thickness's. The crystallinity improves as the Cu buffer thickness increases. The uniaxial anisotropy of the pinned [Ni.sub.80][Fe.sub.20] was greatly enhanced in the samples with thick Cu ([is greater than] 10 nm). This reflects the great effect of film crystallinity on exchange anisotropy. Index Terms--Crystallinity, Cu buffer layer, epitaxial growth, exchange anisotropy.

Complementary nature of coercivity enhancement and exchange bias in a ferro-antiferromagnet (F-AF) exchange coupled system with arbitrary configuration refers to the relation Hsw0-=Ms/χin,max, with Ms being the saturation magnetization of the F part, Hsw0- being the field at which the F magnetization starts to be unstable, applied opposite to the stable direction of the F magnetization in the absence of external field, and χin,max being the maximal initial susceptibility, for which the field is applied perpendicular to that stable direction. This relation is a special case of a more general result for a single domain particle, proved in this paper. In a F-AF system, when the F magnetization behaves coherently, the effect of F-AF coupling can be absorbed into the anisotropy of the F part and the system can be treated as a single domain in an external field. [ABSTRACT FROM AUTHOR]

A circuit with two long parallel micron size wires was fabricated by photolithography to calibrate magnetic force microscopy (MFM) tips. The tip phase shift increased as the tip scan height decreased. With the tip scan height kept constant, a linear relationship was found between the current amplitude and the phase shift of the tip at the center position of the two wires separation. The estimated magnetic moment of the tip was one order larger than its nominal value. The results imply that with better control over the fabrication process, the micron size straight wires can be used to calibrate MFM tips. [ABSTRACT FROM AUTHOR]

The effect of interface roughness on exchange bias for NiFe/FeMn bilayers is investigated for polycrystalline films and epitaxial films. Three different systems were investigated: polycrystalline Ta (10 nm)/Ni[sub 80]Fe[sub 20] (10nm)/Fe[sub 50]Mn[sub 50] (20 nm) films on oxygen plasma-etched Si(100) or Cu/H–Si(100) and epitaxial Ni[sub 80]Fe[sub 20] (10nm)/Fe[sub 60]Mn[sub 40] (20 nm) films on Cu/H–Si(110). For films grown on plasma-etched substrates, as the etching time is increased, film roughness increases up to 12 nm. For the polycrystalline films grown on ultrathin Cu underlayers, x-ray diffraction shows the fcc (111) texture is greatly reduced as the thickness is increased. The epitaxial Cu/Si(110) buffer layer induces fcc (111) epitaxial growth and modifies the interface morphology. The dependence of exchange bias on roughness for each set of samples is explained in terms of a competition between the interfacial exchange coupling and the af uniaxial anisotropy. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Discusses a study which investigated the epitaxial growth and magnetic properties of a ferro-antiferromagnetic exchange bilayers. Review of related literature; Materials and methodology used; Results and conclusions.

Abstract: Si1−x Mn x diluted magnetic semiconductor films were deposited on p-type Si(100) substrate by radio frequency magnetron sputtering method. Post thermal annealing was performed in an argon atmosphere at 1073K for 300s and at 1473K for 120s. The as-grown sample exhibits ferromagnetism at room temperature. Ferromagnetism is enhanced after annealing treatment. High resolution transmission electron microscopy shows that only Mn4Si7 compound formed in all samples. X-ray diffraction patterns and Fast Fourier Transform image indicate Mn atoms incorporated into Si lattice upon annealing. X-ray absorption fine structure suggests the formation of substitutional–tetrahedral interstitial Mn–Mn and tetrahedral interstitial–substitutional–tetrahedral interstitial Mn–Mn–Mn complexes in the 1473K annealed sample, which possesses the strongest ferromagnetism. [Copyright &y& Elsevier]

Abstract: Si1−x Mn x diluted magnetic semiconductor films were deposited on the p-Si (100) single crystal wafer using magnetron sputtering method. Post-rapid thermal annealing treatments were performed at temperatures of 700 °C, 800 °C, and 900 °C in an argon atmosphere for approximately 5 min. Alternating gradient magnetometer, scanning electron microscope, atomic force microscope, X-ray diffraction and X-ray absorption near-edge structure spectra were employed to characterize magnetic properties and structure of the as-grown and annealed films. The films were about 2.8 μm thick and the RMS roughness of the surface was about 5–10 nm. All samples exhibit ferromagnetism at room temperature and the saturation magnetization reaches at the maximum value for the sample annealed at 700 °C. The silicide MnSi1.7 was observed in the annealed samples. X-ray absorption near-edge structure spectra indicated that Mn atoms preferred to occupy substitutional or interstitial sites instead of precipitating to form silicide when annealing at 700 °C. It is inferred that the observed ferromagnetism is attributed to the interstitial and substitutional Mn dimers, which existed mostly in the sample annealed at 700 °C. The weaker ferromagnetism of the 900 °C annealed sample was closely related to the increased content of Mn4Si7 compound. [Copyright &y& Elsevier]