## Magnetotransport effects of ultrathin Ni80Fe20 films probed in situ

2010
##### Authors
Schmidsfeld, Alexander von
Journal article
##### Published in
New Journal of Physics ; 12 (2010). - 013001
##### Abstract
We investigated the magnetoresistance of Permalloy (Ni80Fe20) films with thicknesses ranging from a single monolayer to 12 nm, grown on Al2O3, MgO and SiO2 substrates. Growth and transport measurements were carried out at 80K in UHV. Applying in-plane magnetic vector fields up to 100mT, the magnetotransport properties were ascertained during growth. With increasing thickness the films exhibited a gradual transition from tunnelling magnetoresistance to anisotropic magnetoresistance. This corresponds to the evolution of the film structure from separated small islands to a network of interconnected grains, as well as the film s transition from superparamagnetic to ferromagnetic behaviour. Using an analysis based on a theoretical model of island growth, we found that the observed evolution of the magnetoresistance in the tunnelling regime originated from changes in the island size distribution during growth. Depending on the substrate material, significant differences in the magnetoresistance response in the transition regime between tunnelling magnetoresistance and anisotropic magnetoresistance were found. We attributed this to an increasingly pronounced island growth, and to a slower percolation process of Permalloy when comparing growth on SiO2, MgO and Al2O3 substrates. The different growth characteristics resulted in a markedly earlier onset of both tunnelling magnetoresistance and anisotropic magnetoresistance for SiO2. For Al2O3 in particular the growth mode results in a structure of the film containing two different contributions to ferromagnetism, which lead to two distinct coercive fields in the high thickness regime.
530 Physics
##### Cite This
ISO 690KRZYK, Stephen, Alexander von SCHMIDSFELD, Mathias KLÄUI, Ulrich RÜDIGER, 2010. Magnetotransport effects of ultrathin Ni80Fe20 films probed in situ. In: New Journal of Physics. 12, 013001. Available under: doi: 10.1088/1367-2630/12/1/013001
BibTex
@article{Krzyk2010Magne-5044,
year={2010},
doi={10.1088/1367-2630/12/1/013001},
title={Magnetotransport effects of ultrathin Ni80Fe20 films probed in situ},
volume={12},
journal={New Journal of Physics},
author={Krzyk, Stephen and Schmidsfeld, Alexander von and Kläui, Mathias and Rüdiger, Ulrich},
note={Article Number: 013001}
}

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<dcterms:abstract xml:lang="eng">We investigated the magnetoresistance of Permalloy (Ni80Fe20) films with thicknesses ranging from a single monolayer to 12 nm, grown on Al2O3, MgO and SiO2 substrates. Growth and transport measurements were carried out at 80K in UHV. Applying in-plane magnetic vector fields up to 100mT, the magnetotransport properties were ascertained during growth. With increasing thickness the films exhibited a gradual transition from tunnelling magnetoresistance to anisotropic magnetoresistance. This corresponds to  the evolution of the film structure from separated small islands to a network of interconnected grains, as well as the film s transition from  superparamagnetic to ferromagnetic behaviour. Using an analysis based on a theoretical model of island growth, we found that the observed evolution of the magnetoresistance in the tunnelling regime originated from changes in the island size distribution during growth. Depending on the substrate  material, significant differences in the magnetoresistance response in the transition regime between tunnelling magnetoresistance and anisotropic magnetoresistance were found. We attributed this to an increasingly  pronounced island growth, and to a slower percolation process of Permalloy when comparing growth on SiO2, MgO and Al2O3 substrates. The different growth characteristics resulted in a markedly earlier onset of both tunnelling magnetoresistance and anisotropic  magnetoresistance for SiO2. For Al2O3 in particular the growth mode results in a structure of the film containing two different contributions to ferromagnetism, which lead to two distinct coercive fields in the high  thickness regime.</dcterms:abstract>
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Yes