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arXiv · 1311.1439

Magnetoresistance of granular Pt-C nanostructures close to the metal-insulator-transition

Fabrizio Porrati·Roland Sachser·Michael Huth
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Abstract

We investigate the electrical and magneto-transport properties of Pt-C granular metals prepared by focused-electron-beam induced deposition. In particular, we consider samples close to the metal-insulator-transition obtained from as-grown deposits by means of a low- energy electron irradiation treatment. The temperature dependence of the conductivity shows a lnT behavior with a transition to square root of T at low temperature, as expected for systems in the strong-coupling tunneling regime. The magnetoresistance is positive and is described within the wave-function shrinkage model, normally used for disordered system in the weak-coupling regime. In order to fit the experimental data spin-dependent tunneling has to be taken into account. In the discussion we attribute the origin of the spin-dependency to confinement effects of Pt nano-grains embedded in the carbon matrix.

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Fabrizio Porrati, Roland Sachser, Michael Huth. 2013-11-06. Magnetoresistance of granular Pt-C nanostructures close to the metal-insulator-transition. https://arxiv.org/abs/1311.1439

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