Narrow Results

The electronic structures of Co/Cu interface have been calculated by first-principles method based on local spin density approximation. Models 3Co/xCu (x=1-8 monolayers) with different Cu layer thickness are investigated. The results show that the oscillation of the density of states near the Fermi surface with the Cu spacer thickness has been observed and the period of oscillation is about 6 atom layers, which has a good agreement with the corresponding experiments. We also discuss the spin polarization and magnetic resistance with the change of Cu layers thickness. Further analysis shows majority spin states near the Fermi surface played a key role in giant magnetoresistance (GMR).

Based on the previous semi-classical model, we have performed calculation of the giant magnetoresistance (GMR) as a function of the thickness of the top/bottom or center ferromagnetic layers and the non-magnetic layer in dual spin valves. Our results are in good agreement with that reported in experiment, i.e., a GMR maximum is observed when the thickness of the top/bottom magnetic layer is at 20 ~ 40 Å; the GMR value decreases monotonically with the increase of the non-magnetic layer thickness. By considering the "pin-hole" effect, the variation of GMR versus the thickness of the center magnetic layer is also found to be consistent with the experimental result. These calculations will be helpful in the design of high-quality spin-valve structures.

Advances in magnetoresistive type sensors provide a new technique for nondestructive evaluation of metal structures. Giant magnetoresistive and giant magnetoimpedance sensors provide high sensitivity and reduced size with GMI sensors also adding capabilities of high frequency range of measurements. Being produced with thin film processing techniques, the manufacturing cost of these sensors is low. An example is considered of detecting defects in printed circuit boards. System details and experimental results are provided. Computational modeling validation is introduced based on finite element as well as method of moments analysis.

Using atomistic Monte Carlo simulations, we investigated the impact of the interface on the structural properties of iron and copper (Fe/Cu) magnetic multilayers grown by Voronoi diagram. Interest in magnetic multilayers has recently emerged as they are shown to be promising candidates for magnetic storage media, magneto-resistive sensors and personalized medical treatment. As these artificial materials show large differences in properties compared to conventional ones, many experimental and theoretical works have been dedicated on shedding light on these differences and tremendous results have emerged. However, little is known about the influence of the interfaces on magnetic layers. Using numerical approaches, we show that the structure of each layer depends on its thickness and the interface morphology. The Fe and Cu layers can adopt either the body-centered-cubic (bcc) or face-centered-cubic (fcc) structure, while the interface can assume amorphous, bcc, fcc, or a mixture of bcc and fcc structures depending on the layer thicknesses. These results are in good agreement with the experiments. They could be helpful in understanding effects such as giant magneto-resistance from the structural perspective.