The electronic properties of the graphene material were verified

It turns out that graphene is not only the tiniest material possible, but it's also ten times stronger than steel and a better conductor of electricity than any other known material at room temperature.

In the beginning, these were football-shaped balls that were called bucky-balls (fullerenes). Afterwards, these were nanotubes in the form of cylinders. Now, the most fascinating new material in physics and nanotechnology is graphene - a very flat particle consisting of carbon atoms organized in a pattern of hexagonal rings.

Not only is it the tiniest material possible, but it is also ten times stronger than steel and a better conductor of electricity than any other known material at room temperature. These properties of graphene, and its other fascinating properties, are what attracted the attention of physicists - who began to examine them, and nanotechnologists - who began to utilize them for the preparation of innovative mechanical and electrical devices.

"There are two properties that make graphene extraordinary," says Kirill Bolotin, professor of physics and astronomy at Vanderbilt University (Nashville, Tennessee, USA). "First, its molecular structure is so resistant to structural defects that the researchers had to deliberately insert them in order to test the effects of these defects. Second, the electrons that carry the electric charge on them move faster and in general behave as if their mass is much smaller than that measured in ordinary metals or superconductors."

In an article published this month in the prestigious journal Nature, the scientist and his research team report that they have succeeded in producing graphene that is clean enough so that it exhibits a strange electronic phenomenon known as the "partial quantum Hall effect" (Wikipedia entry), in which the electrons work together to create new charged particles Electrics that are a fraction of the charge of a single electron.

Although graphene is the first true two-dimensional crystalline material to be discovered, scientists have pondered over the years how other two-dimensional gases and solids would behave. They were also able to create a close approximation for a two-dimensional electron gas by bonding together two slightly different semiconductors. The electrons are confined at the interface between the two semiconductors and their movement is limited to two-dimensional movement only. When such a system is cooled to less than one degree above absolute zero and a strong magnetic field is applied to it - then the phenomenon occurs.

Ever since scientists figured out how to make graphene (five years ago), they've been trying to get it to exhibit this phenomenon, with only marginal success. According to the researcher, a group from Columbia University in the USA realized that the problem is a disturbance arising from the surface on which the graphene is placed. Following this, the researchers used semiconductor lithography methods to place extremely clean sheets of graphene between microscopic dots on top of the semiconductor chip surface. When they cooled this configuration to a range of up to six degrees above absolute zero and applied a magnetic field, the graphene induced the Hall effect, just as the theory predicted.

The best way to understand this phenomenon, which goes against our normal logic, is to think of the electrons in graphene as if they were creating an extremely thin charged wave. When a magnetic field is applied, this wave produces eddies in the electron stream. Since electrons have a negative charge, these vortices have a positive charge. These "vortices" are obtained with a partial charge of one third, one half and two thirds of the charge of a single electron. These positive charge carriers are attracted to the conduction electrons, and eventually form quasi-particles (quasi-particles) with a partial charge.

Understanding the electronic properties of graphene is important because, unlike other materials used in the electronics industry, graphene remains stable and conductive even at the molecular level. As a result, when current silicon technology reaches its fundamental miniaturization limit in the coming years, graphene may take its place.

Meanwhile, theoretical physicists are interested in graphene for an entirely different reason: it provides new possibilities for testing their theories.

During the movement of electrons within ordinary metals, they react with electric fields created by the lattice of metal atoms, fields that attract and repel them in a complex manner. As a result, the electrons behave as if they have a mass different from their normal, original mass. Therefore, physicists call it "effective mass" and refer to them as quasi-particles. Even when they move around the graphene they behave as quasi-particles, but in such a way that they are massless. It turns out that graphene's quasi-particles, unlike those found in other materials, obey the laws of quantum electrodynamics - the same relativity equations that physicists use to describe the behavior of particles in black holes and high-energy particle accelerators. As a result, this innovative material could allow physicists to conduct actual experiments to test the correctness of their theoretical models for the most extreme environments that exist in the entire universe.

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