- Scientists from the Massachusetts Institute of Technology have discovered a new form of carbon material – PRSG
- PRSG combines unique physical states: insulating, magnetic and topological
- Electron correlation in a given structure promotes superconductivity
Researchers at the Massachusetts Institute of Technology (MIT) have unveiled a new material that not only surpasses the hardness of diamond and the strength of steel, but may also serve as the key to superconducting materials! This is one of the derivatives of graphene with the head-scratching name pentalayer rhombohedral stacked graphene. For simplicity, we will write it as PRSG. First, let’s look at its structure, which is made up of five layers of graphene, which are arranged in a rhombohedral shape. We can imagine a rhombohedral structure as two oppositely connected pyramids facing each other. Today’s article will be devoted to this structure, because it is responsible for the unique properties of this material.
What is the dizpart between graphene and PRSG?
First, we look at how PRSG differs from graphene, from which it is derived. Graphene consists only of a monoatomic carbon layer, which is arranged in the shape of honeycombs. Graphene offers a number of unique properties, such as high tensile strength or excellent electrical conductivity. A new study shows that in order to achieve better electrical conductivity of graphene, the graphene layer needs to be twisted into specific shapes, which is very problematic from a practical point of view. On the contrary, PRSG is characterized by the fact that there is no need to modify (twist) its structure into specific shapes in order to manifest its new physical properties.
Correlation between two electrons that can occur in some forms of carbon materials (illustrative image)
As we have already mentioned, the structure of PRSG is quite specific. In this structure, the electrons are placed closer together, which leads to their mutual influence, known as electron correlation. This phenomenon means that the movement of one electron can affect the movement of another electron. It may not look like that at first glance, but the movement of electrons in the PRSG is organized thanks to the unique structure of the PRSG. In common materials, electrons are usually separated by large distances, causing minimal interaction between their motions. The presence of electron correlation is a key factor because it brings us closer to superconducting materials, which are known for their zero electrical resistance.
PRSG changes its physical properties when the electrical voltage changes
The MIT researchers further focused on the PRSG’s response to a change in electrical voltage. To measure the voltage, it was necessary to place the PRSG between two layers of boron nitride. Subsequently, electrical voltage was applied to the electrodes. During this study, it was noted that depending on the magnitude of the applied voltage, the PRSG exhibits three distinct states, namely: insulating, magnetic, and topological states. There would be nothing interesting about these properties except for one small thing… Currently, there is a very limited amount of materials that could combine these properties together, with a few exceptions, which is PRSG.
If the applied electrical voltage to the sample is low, the PRSG exhibits insulating properties, simply speaking it behaves as an insulator and does not conduct any electrical current. Let’s be honest, it’s not that interesting a feature. If we increase the magnitude of the applied voltage, the material goes into a magnetic state, when it starts to show a magnetic moment, we can simply imagine that it starts to react to the presence of a magnetic field. If we increase the tension even more, we reach the last and most interesting state! We will call it the topological state. What makes this condition so special?
How does topological conductivity manifest itself in conductive materials?
First, let’s talk about what topological conductivity means, and we’ll start with conductors. In the case of conductors, topological conductivity is caused by a specific arrangement of electrons that allows them to move freely. Such an arrangement can lead to an improvement in the electrical properties of the conductors, such as increased electrical conductivity or reduced electrical resistance. In the case of insulators, topological conductivity is caused by the electrons being arranged in a specific arrangement that prevents them from moving freely.
MIT scientists examining surface morphology of PRSG using atomic force microscopy (illustrative image)
Properties that are characteristic of topological elements are manifested precisely in the case of PRSG. We can think of this situation as having areas in the material where electrons can pass through quickly. These areas are mostly on the outside. Conversely, the center exhibits insulating properties that limit the movement of electrons. In other words, the edge of the topological material serves as a perfect conductor, while the central part acts as an insulator, which is a key element for its characteristic properties.
Not only faster and more economical transistors
A new graphene material has the potential to impact our daily lives. It opens up the possibility of developing new technologies with greater performance, durability and lower weight compared to current technologies. PRSG could, for example, be used in the production of new types of transistors that would be faster and more energy efficient. This advancement could push the boundaries of electronics, bringing more powerful devices like computers.
PRSG also offers potential use in the field of superconducting cables. Current superconducting cables are usually made of metals such as niobium or lanthanides. Unfortunately, superconducting cables are limited by their critical temperature, often below 100°C, and require liquid nitrogen cooling, which is energy- and cost-intensive. PRSG could be used to produce superconducting cables that could be air- or water-cooled, resulting in substantial cost and energy savings.
Author of the article
Josef Novak
I am a PhD student dealing with ion applied technologies, because I have always been fascinated by science and technology. I never cease to be amazed at what can be created thanks to human creativity and abilities. I like to spend my free time traveling, either in the mountains or in the cities.
2023-12-19 08:00:00
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