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  • Jakub Rudnicki
    • 4 min read

Unleashing the Power of Superconductors: Revolutionizing Modern Technology

Superconductors are materials that exhibit zero electrical resistance and perfect diamagnetism below a certain critical temperature. Since their discovery in 1911, superconductors have revolutionized fields such as power generation and transmission, medical imaging, and transportation. They offer the promise of highly efficient, low-cost electrical devices, and the potential for new scientific discoveries. This article will summarise in scientific detail, the essence of superconductors and how they function.


These almost supernatural materials share two main properties: they expel magnetic fields and allow for electrical superconductivity.


Electrical resistance is the amount of opposite flowing current. A superconductor in its superconducting state, allows for no electrical resistance because the vibrations and flaws from the collisions of other electrons in the metal that would otherwise cause resistance, do not. This being because of a phenomenon described in the BCS (Barden, Cooper and Schrieffer) model.


The BCS model, established in 1957 following the discovery of superconductivity in 1911, states that superconductivity occurs because electrons pair together. Therefore, mitigating any obstructions and collisions, allowing for no resistance.


The pairs are formed because of various disturbances of positive charge within the material. Electrons traveling through a circuit towards the positive part of the battery, subtly attract positively charged atoms (each atom has lost its electrons due to conduction), causing a local disturbance in the hundreds of thousands of cations nearby. Electrons travelling close, would be attracted to this disturbance. As we know, like charges repel. However, in this scenario, the electrons are pushed together towards the mutual point of positive charge. The electrons then bind together, to form a cooper pair.


The bond between the two electrons is extraordinarily weak and can be broken by the smallest of vibrations, which leads us to understand why superconductors best operate at low temperatures (<-250*C) as such that thermal vibrations are negligible.


As a cooper pair is created, the electrons involved are still fermions, though they share the properties of bosons. Protons, neutrons, and electrons could be referred to as fermion particles. Such particles do not have the ability to occupy the same quantum state. Considering electrons, this would mean that once a shell Is full, an electron must occupy one of the higher energy shells. This being because it would be impossible for it to occupy the same place as the electrons which are already fulfilling the maximum number of electrons in the first shell. Albeit boson particles have the ability of being in the same state as other electrons, allowing the electrons to clump together. Since a copper pair shares the qualities of a Bosons, such phenomenon also allows for cooper pairs to overlap with other cooper pairs, creating a large network of interactions.

Fig 2 (cooper pair) (own drawing)


The properties of superconductors also allow for them to interact with magnetic fields in a much different way to that of other materials. This being, that superconductors allow for the expulsion of magnetic fields from their core; known as the Meissner effect.


To investigate the Meissner effect, we may compare the difference in the behaviour of Superconductors and Perfect diamagnets when exposed to steady magnetic fields. In their non-resistive state, the materials allow for magnetic fields to pass through them regularly. When a regular conductor is cooled to its zero-resistive state, there is little to no change; the magnetic fields are expected to stay the same. In contrast, when a superconductor enters the superconducting state, it will actively expul magnetic field present. This may be referred to as Perfect Diamagnetism.


As a material enters the superconducting state, it manages to actively exclude magnetic fields from its interior. According to Lens’s and Faradays law, circulating currents within a conductor will be induced to oppose the build-up of magnetic fields. Furthermore, the better the conductor, the better the diamagnet. There is much more than this involved in the Meissner effect, but this is the basic principle that allows for its existence.


Superconductors are remarkable materials that have transformed multiple industries, including power generation and transportation, by providing highly efficient, low-cost electrical devices. The discovery of superconductivity in 1911 paved the way for the BCS model, which explains the pairing of electrons and the absence of electrical resistance in these materials. Superconductors also exhibit perfect diamagnetism, known as the Meissner effect, which allows for the expulsion of magnetic fields from their core. While the properties of superconductors are still being researched, they hold immense potential for future scientific discoveries and technological advancements.


References

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