119 research outputs found
Transport Gap in Suspended Bilayer Graphene at Zero Magnetic Field
We report a change of three orders of magnitudes in the resistance of a
suspended bilayer graphene flake which varies from a few ks in the high
carrier density regime to several Ms around the charge neutrality point
(CNP). The corresponding transport gap is 8 meV at 0.3 K. The sequence of
appearing quantum Hall plateaus at filling factor followed by
suggests that the observed gap is caused by the symmetry breaking of the lowest
Landau level. Investigation of the gap in a tilted magnetic field indicates
that the resistance at the CNP shows a weak linear decrease for increasing
total magnetic field. Those observations are in agreement with a spontaneous
valley splitting at zero magnetic field followed by splitting of the spins
originating from different valleys with increasing magnetic field. Both, the
transport gap and field response point toward spin polarized layer
antiferromagnetic state as a ground state in the bilayer graphene sample. The
observed non-trivial dependence of the gap value on the normal component of
suggests possible exchange mechanisms in the system.Comment: 8 pages, 5 figure
Field induced quantum-Hall ferromagnetism in suspended bilayer graphene
We have measured the magneto-resistance of freely suspended high-mobility
bilayer graphene. For magnetic fields T we observe the opening of a field
induced gap at the charge neutrality point characterized by a diverging
resistance. For higher fields the eight-fold degenerated lowest Landau level
lifts completely. Both the sequence of this symmetry breaking and the strong
transition of the gap-size point to a ferromagnetic nature of the insulating
phase developing at the charge neutrality point.Comment: 7 pages, 5 figure
Coexistence of electron and hole transport in graphene
When sweeping the carrier concentration in monolayer graphene through the
charge neutrality point, the experimentally measured Hall resistivity shows a
smooth zero crossing. Using a two- component model of coexisting electrons and
holes around the charge neutrality point, we unambiguously show that both types
of carriers are simultaneously present. For high magnetic fields up to 30 T the
electron and hole concentrations at the charge neutrality point increase with
the degeneracy of the zero-energy Landau level which implies a quantum Hall
metal state at \nu=0 made up by both electrons and holes.Comment: 5 pages, 6 figure
Global transcriptional response of Saccharomyces cerevisiae to the deletion of SDH3
<p>Abstract</p> <p>Background</p> <p>Mitochondrial respiration is an important and widely conserved cellular function in eukaryotic cells. The succinate dehydrogenase complex (Sdhp) plays an important role in respiration as it connects the mitochondrial respiratory chain to the tricarboxylic acid (TCA) cycle where it catalyzes the oxidation of succinate to fumarate. Cellular response to the Sdhp dysfunction (i.e. impaired respiration) thus has important implications not only for biotechnological applications but also for understanding cellular physiology underlying metabolic diseases such as diabetes. We therefore explored the physiological and transcriptional response of <it>Saccharomyces cerevisiae </it>to the deletion of <it>SDH3</it>, that codes for an essential subunit of the Sdhp.</p> <p>Results</p> <p>Although the Sdhp has no direct role in transcriptional regulation and the flux through the corresponding reaction under the studied conditions is very low, deletion of <it>SDH3 </it>resulted in significant changes in the expression of several genes involved in various cellular processes ranging from metabolism to the cell-cycle. By using various bioinformatics tools we explored the organization of these transcriptional changes in the metabolic and other cellular functional interaction networks.</p> <p>Conclusion</p> <p>Our results show that the transcriptional regulatory response resulting from the impaired respiratory function is linked to several different parts of the metabolism, including fatty acid and sterol metabolism.</p
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