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# Search results

97 records were found.

## Raman imaging and electronic properties of graphene

Graphite is a well-studied material with known electronic and optical properties. Graphene, on the other hand, which is just one layer of carbon atoms arranged in a hexagonal lattice, has been studied theoretically for quite some time but has only recently become accessible for experiments. Here we demonstrate how single- and multi-layer graphene can be unambiguously identified using Raman scattering. Furthermore, we use a scanning Raman set-up to image few-layer graphene flakes of various heights. In transport experiments we measure weak localization and conductance fluctuations in a graphene flake of about 7 monolayer thickness. We obtain a phase-coherence length of about 2 $\mu$m at a temperature of 2 K. Furthermore we investigate the conductivity through single-layer graphene flakes and the tuning of electron and hole densities v...

## Analytic Model for the Energy Spectrum of a Graphene Quantum Dot in a Perpendicular Magnetic Field

Comment: 4 pages, 3 figures

## Graphene quantum dots in perpendicular magnetic fields

Comment: 5 pages, 4 figures, submitted to pss-b

## Spin States in Graphene Quantum Dots

We investigate ground and excited state transport through small (d = 70 nm) graphene quantum dots. The successive spin filling of orbital states is detected by measuring the ground state energy as a function of a magnetic field. For a magnetic field in-plane of the quantum dot the Zemann splitting of spin states is measured. The results are compatible with a g-factor of 2 and we detect a spin-filling sequence for a series of states which is reasonable given the strength of exchange interaction effects expected for graphene.

## Transport through a strongly coupled graphene quantum dot in perpendicular magnetic field

Comment: 6 pages, 4 figures

## Coulomb Gap in Graphene Nanoribbons

We investigate the density and temperature-dependent conductance of graphene nanoribbons with varying aspect ratio. Transport is dominated by a chain of quantum dots forming spontaneously due to disorder. Depending on ribbon length, electron density, and temperature, single or multiple quan- tum dots dominate the conductance. Between conductance resonances cotunneling transport at the lowest temperatures turns into activated transport at higher temperatures. The density-dependent activation energy resembles the Coulomb gap in a quantitative manner. Individual resonances show signatures of multi-level transport in some regimes, and stochastic Coulomb blockade in others.

## Transport in a three-terminal graphene quantum dot in the multi-level regime

Comment: 12 pages, 6 figures

## Operating a phase-locked loop controlling a high-Q tuning fork sensor for scanning force microscopy

Comment: 10 pages, 8 figures

Comment: 4 pages

## Phase coherent transport in a side-gated mesoscopic graphite wire

Comment: 5 pages, 4 figures