We investigate phase-coherent transport and show Aharonov-Bohm (AB) oscillations in quasiballistic graphene rings with hard confinement. Aharonov-Bohm oscillations are observed in a graphene quantum ring with a topgate covering one arm of the ring. As graphene is a gapless semiconductor, this. Graphene rings in magnetic fields: Aharonov–Bohm effect and valley splitting. J Wurm1,2, M Wimmer1, H U Baranger2 and K Richter1. Published 3 February.

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The Aharonov–Bohm effect in a side-gated graphene ring

While the earlier research interests were focused on the most basic nanostructures, e. Figure 4 a Schematic representation of the different ring geometries of samples 1 and 2. The main advantage of graphene compared to metals for Aharonov—Bohm studies is the reduced screening. It has a worldwide membership of around 50 comprising physicists from all sectors, as well as those with an interest in physics.

[] The Aharonov-Bohm effect in graphene rings

It supports the sharing of ideas and thoughts within the scientific community, fosters physics teaching and would also like to open a window to physics for all those with a healthy curiosity.

Graphee relevance of thermal averaging of phase-coherent effects can be judged from the thermal lengthwhich is significantly smaller than L. A smaller radius will lead to a larger oscillation amplitude, which may explain the improved amplitude in our measurements.

B 75 Crossref. The only relevant effect of the magnetic field on the charge carrier dynamics is therefore caused by the field-induced Aharonov—Bohm phase.

For b the background resistance has been subtracted as described in the text. In addition, our graphene ring has better tunability as it is equipped not only with a back gate, which allows us to change the charge carrier density in the complete sample, but also with side gates, allowing a local tuning of the charge carrier density in one of the arms. We graphsne low-temperature magnetotransport measurements on graphene rings encapsulated in hexagonal boron nitride.


[] Aharonov-Bohm oscillations and magnetic focusing in ballistic graphene rings

Since then, amazing progress in the gfaphene of increasingly more complex nanostructures has been made. A magnetic field is applied perpendicular to the sample plane. The red trace in the inset corresponds to the mirrored and vertically offset negative B -field branch. The observed data can be interpreted within existing models for dirty metals. The conductance for the disk is shown for different strength of edge roughness with the result that the gdaphene of the conductance minima are rather robust to edge roughness.

Condensed Matter > Mesoscale and Nanoscale Physics

Minima and maxima of the conductance are approximately horizontal and vertical on this plot. Its publishing company, IOP Publishing, is a world leader in professional scientific communications.

We observe that the trajectory of the electron starting in the left lead performs a skipping orbit which after four reflections at the boundary enters the right lead.

Bachtold A et al Nature Crossref. This site uses cookies.

The Bomh wavelength corresponding to the carrier density mentioned above is. Therefore measurements presented here were taken over only small ranges of back gate voltage after having allowed the sample to stabilize in this range.


Note that the results also approximately match the results of Fig. Values are normalized with respect to the conductance at zero B field and an offset is added for gfaphene. The data are analyzed by a simple dirty metal model justified by a comparison of the different length scales characterizing the system. The amplitude of the Aharonov—Bohm oscillations is modulated as a function of magnetic field on the same scale as the background resistance, indicating that a finite number of paths enclosing a range of different areas contribute to the oscillations.

Figure 2 a Solid black line: By continuing to use this site you agree to our use of cookies.

It works to advance physics research, application and education; and engages with policy makers and the public to develop awareness and understanding of physics. A close up of the 4. This indicates that thermal averaging of interference contributions to the conductance is expected to be relevant.

Arrows indicate the direction of the edge channels. However, due to limited sample stability, the visibility of the oscillations at a given back gate voltage depends on the back gate voltage history. We therefore speculate that the paths contributing to transport, in general, and to the Aharonov—Bohm effect, in particular, may not cover the entire geometric area of the ring arms.