Students: Alexei Zubarev *and Camelia Sold**

*Faculty of Physics, University of Bucharest

**Faculty of Physics, West University of Timisoara

Coordinators***: D. Kolesnikov, V. Katkov

***Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna

Carbon nanostructures

Graphene Nanotubes Graphene pillars

Nanotubes propertiesNanotubes have a very broad range of electonic, thermal, and structural properties that change depending on the different kinds of nanotube (defined by its diameter, length, and chirality, or twist). To make things more interesting, besides having a single cylindrical wall (SWNTs), nanotubes can have multiple walls (MWNTs)--cylinders inside the other cylinders. Currently, the physical properties are still being discovered and disputed.

Electrons in nanotubesThe behavior of electrons is descibed by the Dirac equation:

Nanotubes under magnetic field

Magnetic flux:

Dirac equations for ΨT=(Ψ1 ,Ψ2) have the following form:

Magnetic barrier

Rotational deformation

α

Rotational deformation is equivalent to magnetic field

ResultsTransmission in function of rotational deformation: T(α)

L=10 , 5, 2, 1

Metallic channel

Secondary channel

m = 0

L = 0.05, 0.5, 1, 2

m = 1

Results

E = 0.01, 0.5, 0.7, 1

The transmission dependence on deformation for different energies

Transmission value doesn’t depend significantly on energy

The transmission dependence on deformation if we rotate only the centre of the nanotube

The secondary channels don’t influence significantly the value of transmission

m = 0

m = -1

m = 1

Conclusions Transmission doesn’t depend significantly on energy Transmission decreases when the nanotube length

increases For the main channel, transmission decreases sharply

when deformation (magnetic field) increases For the main channel, transmission depends only on

the total deformation For the secondary channel (electrons with positive m),

transmission decreases when deformation increases

Possible applications

Using nanotubes we can assemble an electronical device that works based on magnetic field. The signal decreases sharply when magnetic field is applied.

The results we obtained can be applied to make a sensor similar to Coulomb Balance. The value of force can be measured by the current variation.