Dissertations, diploma thesis, thesis and examination papers in institutes for anthropology 1993

Editor, The

doi:10.1127/anthranz/52/1994/357

Cited by 7 publications

(8 citation statements)

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“…Hence we may assume that the exchange coupling between the grains is weakened or even interrupted. EDX-microbeam analysis has shown the content of Ga and Nb within this intergranular region is twice as large as that in the matrix grains [19]. It is therefore suggested that, in this case, the grains are coupled only by the much weaker long-range dipolar stray fields.…”

Section: Nanocrystalline Magnetsmentioning

confidence: 86%

“…As in the case of the mechanically alloyed magnet of figure 5, this remanence enhancement is attributed to the exchange coupling between the grains. Figures 7 and 8 give a comparison of the high-resolution transmission electron microscopy photographs [19], showing a singlephase nanostructure for the stoichiometric alloy and a twophase nanostructure for the alloy with additives. Whereas in the first case the grain boundaries appear to connect the neighbouring grains without any intergranular layer, namely, with exchange coupling, in the other case we observe a second phase between the grains of width 2 nm, which seems to be amorphous.…”

Section: Nanocrystalline Magnetsmentioning

confidence: 99%

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Micromagnetism and microstructure of hard magnetic materials

Kronmüller

Fischer

Seeger

et al. 1996

J. Phys. D: Appl. Phys.

160

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High-performance magnetic materials are based on outstanding intrinsic magnetic properties and optimized microstructures and alloy compositions. The interactions between these three parameters in general are rather complex and cannot be treated explicitly by the theory of micromagnetism. Instead numerical methods have to be applied in order to determine the characteristic properties of hysteresis loops. Within the framework of computational micromagnetism (nanomagnetism) using the finite-element method the coercive fields of different types of grain ensembles have been determined. In the case of nanocrystalline composites the roles of grain size, exchange and dipolar coupling between grains will be discussed in detail. It is shown that, in sintered magnets, large coercivities require magnetic de-coupling between the grains, whereas regions with exchange coupling reduce the coercive field drastically, but, however, increase the remanence. Nanocrystalline composite materials with remanence enhancement and high coercivities are shown to require soft grains with diameters of twice the wall width of the hard magnetic phase. For an amount of 50% -Fe coercivities of , a remanence of 1.5 T and an energy product of are expected. A quantitative analysis of the numerical results for and the remanence leads to logarithmic dependences on grain size.

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Section: Nanocrystalline Magnetsmentioning

confidence: 86%

Section: Nanocrystalline Magnetsmentioning

confidence: 99%

Micromagnetism and microstructure of hard magnetic materials

Kronmüller

Fischer

Seeger

et al. 1996

J. Phys. D: Appl. Phys.

160

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show abstract

“…In the wide band limit ln g R (t, λ) can be calculated analytically also for an energy-independent transmission probability which differs from one [14].…”

Section: Perfect Transmissionmentioning

confidence: 99%

Full counting statistics for noninteracting fermions: exact finite-temperature results and generalized long-time approximation

Schönhammer

2009

J. Phys.: Condens. Matter

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Abstract. Exact numerical results for the full counting statistics (FCS) of a onedimensional tight-binding model of noninteracting electrons are presented at finite temperatures using an identity recently published by Abanov and Ivanov. A similar idea is used to derive an explicit expression for the cumulant generating function for a system consisting of two quasi-one-dimensional leads connected by a quantum dot in the long time limit, generalizing the Levitov-Lesovik formula for two single channel leads to systems with an arbitrary number of transverse channels.

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“…A video camera (JVC TK-C1481BEG, JVC, Japan) was installed on the microscope and connected to a PC by a frame grabber card (HaSoTec GmbH, Rostock, Germany). A home-made software package [18,19] was developed for automatic control of the microscope, the piston pumps and the image processing. The video images and films were evaluated by correlation analysis of digital grey patterns with a shifting reference window [20,21] using ARAMIS Software (GOM mbH, Braunschweig, Germany) or the image processing program Analysis 3.1 (SIS Soft Imaging System GmbH, Münster, Germany).…”

Section: Accepted Manuscriptmentioning

confidence: 99%