Stanene :- A Material With 100% Conductivity.

 Introduction –

                                                   ‘Copper just wait, Stanene is coming’

 So, what exactly is this stanene?       

Stanene (From the Latin stannum meaning tin, which also gives the element its chemical symbol, Sn) the latest cousin of graphene was made by an experimentalist at Shanghai Jiao Tong University.

The sheets of: -

1. Silicene, made with the help of silicone atoms.

2. Phosphorene, made from phosphorous.

3. Germanene, made from germanium.

These have honeycomb lattice of carbon atoms which has spiked thousands of studies into 2D materials.

 

      Those listed above are known to be excellent conductors of electricity, but stanene is extra special based on theory.

      Stanene is one atom thick mesh of tin. The charge carriers in Stanene (i.e., like electrons) can move freely along its edge and because of this Stanene is said to be an example of topological insulator. It is predicted that it is able to conduct electricity without losing heat.

Stanene is a one hundred percent efficient conductor of electricity.

100 % efficiency means no loss in energy, in simple words i.e., while conducting an electric current the conductor (here, Stanene) doesn’t dissipate any energy. But in general case of regular conductors, the main source of energy loss is its resistance to the transmission of current i.e., the flow of electrons. 

The resistance is the opposition to the flow of electrons. It arises due to the collision of electrons of atoms of conductor with each other or with any other obstacles like metal ions, impurities, etc. Here energy is dissipated. Furthermore, at some critical temperature some materials show zero resistance, it is called as a superconductor.

Stanene is an exception for this phenomenon because it exhibits zero resistance, hence no energy loss, at room temperature and above it. As discussed earlier it is called a topological insulator. A material which carries current on the surface/edges of it and the remaining bulk is insulating is called a topological insulator. This is due to quantum spin hall effect. 

What is quantum spin hall effect?

Quantum spin Hall Effect is a unique phase of matter in which the bulk of the material is an insulator, but topological quantum states exist at the edges — carrying up spins and down spins in opposite directions.

Generally, electrons possess positive or negative spins and when they travel around the surface/edges of the topological insulator their spin become aligned to the direction of flow by quantum spin hall effect which constitutes a current. Also due to this effect, electrons cannot reverse their direction of travel even if they encounter any type of obstacle within the material unlike the regular conductor where energy is dissipated in such events. If we consider three-dimensional topological insulator, they can’t travel backwards as stated above but they can still strike each other sideways dissipating energy. But in case of two-dimensional topological insulator as the layer is only monoatomic, electrons become restricted to a single lane, eliminating all interference. 

(image credit: https://www.extremetech.com/wp-content/uploads/2013/11/topical-trivial-insulators.jpg)

Let’s now focus on the structural aspect of the Stanene. Stanene (sp2-sp3 orbital hybridization) has a honeycomb structure but not exactly like the graphene (sp2 orbital hybridization). Stanene is in buckling/corrugated form due to relatively weak bonding arising from large bond length between tin atoms due to which it can’t have stable planar structure. But in buckling form the overlap between andorbital is increased which stabilizes the structure. This characteristic structure enables Stanene to show Quantum spin hall effect and ultimately leads to 100 % effiency.

(image credit: https://aip.scitation.org/action/showOpenGraphArticleImage?doi=10.1063/5.0020168&id=images/medium/5.0020168.figures.online.highlight_f1.jpg)

Stanene has a strong spin orbital coupling than graphene hence it can act as a topological insulator and conduct with 100% efficiency.

What is spin orbital coupling?

An interaction between the orbital angular momentum and the spin angular momentum of an individual particle, such as an electron.

It is the cause of Spin Hall Effect.

Adding fluorine atoms in the structure of Stanene, it can conduct with such a full efficiency at 1000 C. According to the discovery by Nature Physics 2018, it is possible to have a phase transition of Stanene to superconductivity by stacking its layers. 

Applications of Stanene :-

Researchers stated that stanene could be used in wiring systems that link various parts of a microprocessor as the free flow of electrons in the wiring would significantly lower the heat generation and power consumption of microprocessors. They also said that stanene could be potentially used to improve the speed and reduce the power consumption of computer chips in the future.

Moreover, researchers believe that stanene could be used as a replacement for silicon in transistors. Manufacturing challenges, however, include ensuring the deposition of a single layer of tin and maintaining the single layer intact during chip manufacturing processes.

A material made up of tin atoms arranged in a single layer could be the world’s first electrical conductor with 100% efficiency, which would make it more conductive than graphene at and even above room temperature.

Stanene can be widely used in electronics, optoelectronics, spintronics, chemistry, thermotics, mechanics, and sensor nanosystems.

Stanene is a topological insulator. The electrons can travel with practically no resistance whatsoever. This makes stanene useful for nanoelectric wiring. With stanene nanowiring, the power consumption and space taken up by electrical current conductors in circuits could be reduced. The result would be faster, more efficient, and smaller integrated circuits.

They also have unique properties relating to the spin of the electrons. The electrons that can move along the outside edge of the topological insulator are also insulated from quantum effects that would flip their spin.2D topological insulators can carry “chiral currents,” where the spins of the electrons are locked into the direction of transport, transferring information. Traditional digital electronics essentially uses the charge on the electron as a means of storing and processing information, so these materials could be invaluable for those who want to use the electron’s spin to encode and transfer information. This opens up a new field of spintronics.

Stanene has a much lower phonon thermal conduction than graphene. Indeed, at room temperature, electron thermal conduction in stanene is roughly the same as its phonon conduction. 

Stanene deviates from the Wiedemann-Franz law, which states that electron thermal conduction depends on the temperature and the electrical conductivity of the material. In stanene, however, the contribution of electron thermal conduction to overall heat transfer also depends on the material’s ‘chemical potential’— a measure of how much energy is required to add one more electron to the material. Crucially, the researchers found that chemical potential also affects electron thermal transport in graphene and some other 2D materials. The surprising findings could make stanene useful in thermoelectric devices, in which a temperature gradient creates a voltage between two parts of a material, or vice versa.

Blog Credits :- Madhura Mahamuni, Vidya Kadam, Avishkar Kale

Resource link :

https://www.scientificamerican.com/article/could-atomically-thin-tin-transform-electronics/

https://onlinelibrary.wiley.com/doi/abs/10.1002/andp.201900017

Physicists announce graphene’s latest cousin: stanene | Nature

https://www.azom.com/article.aspx?ArticleID=15496

https://www.azonano.com/article.aspx?ArticleID=3742

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