GRAPHENE VALLEYTRONICS

Gaurav Kumar

INTRODUCTION:

Graphene has been a well-known compound since its discovery and has been dubbed the “wonder material.” It is rarefied among material scientists because of its potential. It is a well-known truth that it has better qualities. The hardest substance ever discovered is graphene. Is a material that transfers heat and electricity, and is practically indestructible. Transparent, when exposed to molecules, it heals itself. Hydrocarbons, for example, are carbon-based.

The band-gap features of graphene, on the other hand, have ushered in a revolutionary new sector known as valleytronics. The charge of a capacitor is the same as it is in traditional electronics. In order to compute, the electron is used.

The valley number of an electron is employed in valleytronics. It’s classified as a quantum phenomenon. computing, as well as spintronics in today’s world. It makes use of an el’s spin direction.

GRAPHENE’S ENERGY SPECTRUM:

A hexagonal pattern of atoms in two dimensions is graphene. The K and the K’ are two minimums or valleys in its energy spectrum Valley.

These two energy levels, which are both degenerate, are Unique wave-length and It’s possible to store bits using momentum. In the presence of electrons, A superposition of these two can exist as graphene.

 The number of possible outcomes Graphene is a semiconducting material that can be used in a variety of applications. The bandgap between the valance and conduction bands in graphene is zero, making it a semiconductor. As a result, they collide at the Dirac points.

PSEUDO MAGNETIC FIELD IN GRAPHENE:

Electrons react as if they are experiencing an external force field when a perfect planar sheet of graphene is deformed in the same manner that nanobubbles are. Electrons in the K and K’ experience forces in opposite directions as a result of the force. As a result, the field serves as a valley filter.

These principles, however, are quite broad, and different deformations result in forces on electrons with varied paths. This pseudo-magnetic field is being studied and controlled by researchers at CNG, which is part of DTU nanotech. Straintronics and valleytronics are linked by this strain-produced field.

Valley electrons are thought to have superior strain management than substrate c electrons.

GENERATION VALLEY CURRENTS:

The flow of valley currents in graphene is caused by the interaction of graphene with hexagonal boron nitride (hBN).

Valley current has been observed in graphene devices formed over a hexagonal boron nitride layer. The hBN substrate is responsible for disrupting the symmetry between the honeycomb lattice’s two sub-lattices, resulting in an energy gap at the Dirac points. A valley divides people.

Fig. 1
Valleytronic device based on a folded bilayer graphene. a Components of the folded bilayer graphene (folded-BLG) valleytronic device. The folded-BLG is sandwiched by hexagonal boron nitride (hBN) crystals that separate the material from the metallic gates. Under a transverse electric field, the bulk behaves likely semiconductor with band gap and a topological 1D conducting channel forms at the curved boundary, where the valley-index defines the direction of propagation. b Optical image of a folded-BLG transferred on top of the bottom hBN flake. Dashed lines indicate the position of the electric terminals. Scale bar: 4 μm. c A false-color atomic force microscopy (AFM) image of device 1 before the transference of the top hBN. The AFM measurement reveals that the curved boundary is free from contamination of fabrication processes. Scale bar: 1 μm. d Electrostatic potential energy (Δ/2) of the bilayer graphene (BLG) layers, calculated relative to the center of each BLG. The layer energies reverse sign from the bottom BLG to the top BLG and vanish across the curved boundary, where the electric field is parallel to the layers. This variation of the electrostatic potential energy enables the formation of a domain wall at the curved boundary. e Illustration of the pair of kink states localized at inequivalent points K and K’ in the Brillouin zone of BLG, having opposite group-velocities for different valleys. In the domain wall, these edge states propagate in opposite one-dimensional directions due their chiral nature
Cr: Communications Physics (Commun Phys) ISSN 2399-3650 (online)

The ability of graphene to produce valley currents is the most important element of valleytronics because an electronic interface is required if it is to be implemented at all. Valley FETs built of graphene are the most commonly used by researchers.

LIGHT-BASED VALLEYTRONICS:

A wave of light To process logic, valleytronics employs powerful light waves at electron moments. It all begins with a two-dimensional semiconductor or a single fractured material with distinct conduction capabilities.

The electron favors one of two specific momentums in this sort of semiconducting material. Valley is a term that refers to these two distinct momentums. An electrified vehicle demands a substantial amount of energy.

Energy must be introduced by a circularly polarised laser to get the unexcited electron to either valley. A clockwise pulse of circularly polarised light excites the electron in one valley, while an anticlockwise pulse of circulating polarised light excites the electron in another valley.

Because the spin of the light emitted by an electron depends on which valley they are in, the resulting valley state is plainly visible. For a few femtoseconds, the electron will be excited in either valley.

A mechanism to represent a bit of information in two possible values, 0 or 1, in this case, valley 1 or 2, is required in order to build a traditional computer, but that bit must also be able to switch between 0 and 1 to conduct operations.

This is accomplished through the use of high-energy linearly polarised light, which aids the electron in changing momentum and hopping from one valley to the next.

If these systems were applied to build a traditional computer, it would be billions of times quicker than the one we have now.

These quantum states can also exist in quantum superposition with one another, which means that both electrons are in the same state at the same time, somewhere in the middle of 0 and 1. This would allow a quantum computer to be constructed at ambient temperature.

CONCLUSION:

Classical electronics would be unable to deal with the complex issues of the future sciences. The overload of equations in current sciences has already been addressed by quantum computing technologies.

As a result, extensive research is underway to bring valleytronics and spintronics concepts to life. As a result, graphene, formerly thought to be a “wonder material,” is now viewed as a “normal” material.

However, no graphene valley-based gadget has yet been developed. Valleytronics for graphene or other two-dimensional materials is not in the cards anytime soon.

Quantum computing is still a science fiction concept. Furthermore, if valleytronics devices are to be made available to the general people, the cost of graphene becomes a big impediment.

Graphene’s features, however advantageous for valley splitting and valley current production, have yet to be applied to computing.

Sources:

https://www.nature.com/articles/s42005-018-0106-4

https://phys.org/news/2019-07-valleytronics-core-theory-future-high-efficiency.html

TechThoroughFare

Share on facebook
Share on twitter
Share on linkedin
Archives

Leave a Reply

Your email address will not be published. Required fields are marked *

Science

Latest

Trending