Why is a superconductor superconducting

Superconductors have a number of technological applications, from magnetic resonance imaging machines to mobile-phone towers, and researchers are beginning to experiment with them in high-performance generators for wind turbines.

But their usefulness is still limited by the need for bulky cryogenics. Common superconductors work at atmospheric pressures, but only if they are kept very cold. Superconductors that work at room temperature could have a big technological impact, for example in electronics that run faster without overheating. But the latest result marks the first time this kind of superconductivity has been seen in a compound of three elements rather than two — the material is made of carbon, sulfur and hydrogen.

Adding a third element greatly broadens the combinations that can be included in future experiments searching for new superconductors, says study co-author Ashkan Salamat, a physicist at the University of Nevada, Las Vegas.

Surprise graphene discovery could unlock secrets of superconductivity. Materials that superconduct at high but not extreme pressures could already be put to use, says Maddury Somayazulu, a high-pressure-materials scientist at Argonne National Laboratory in Lemont, Illinois. The work also validates decades-old predictions by theoretical physicist Neil Ashcroft at Cornell University in Ithaca, New York, that hydrogen-rich materials might superconduct at temperatures much higher than was thought possible.

Physicist Ranga Dias at the University of Rochester in New York, along with Salamat and other collaborators, placed a mixture of carbon, hydrogen and sulfur in a microscopic niche they had carved between the tips of two diamonds. They then triggered chemical reactions in the sample with laser light, and watched as a crystal formed. As they lowered the experimental temperature, resistance to a current passed through the material dropped to zero, indicating that the sample had become superconductive.

Then they increased the pressure, and found that this transition occurred at higher and higher temperatures. Their best result was a transition temperature of These electron pairs, called Cooper pairs, are very stable at low temperatures, and with no electrons "free" to bounce around, the electrical resistance disappears. Bardeen, Cooper and Schrieffer put these pieces together to form their theory, known as BCS theory, which they published in the journal Physical Review Letters.

When a metal drops below a critical temperature, the electrons in the metal form bonds called Cooper pairs. Locked up like this, the electrons can't provide any electrical resistance, and electricity can flow through the metal perfectly, according to the University of Cambridge. However, this only works at low temperatures. When the metal gets too warm, the electrons have enough energy to break the bonds of the Cooper pairs and go back to offering resistance.

That is why Onnes, in his original experiments, found that mercury behaved as a superconductor at 4. It's very likely that you've encountered a superconductor without realizing it. In order to generate the strong magnetic fields used in magnetic resonance imaging MRI and nuclear magnetic resonance imaging NMRI , the machines use powerful electromagnets, as described by the Mayo Clinic.

These powerful electromagnets would melt normal metals due to the heat of even a little bit of resistance. However, because superconductors have no electrical resistance, no heat is generated, and the electromagnets can generate the necessary magnetic fields. Similar superconducting electromagnets are also used in maglev trains, experimental nuclear fusion reactors and high-energy particle accelerator laboratories. Superconductors are also used to power railguns and coilguns, cell phone base stations, fast digital circuits and particle detectors.

Essentially, any time you need a really strong magnetic field or electric current and don't want your equipment to melt the moment you turn it on, you need a superconductor. This was the very first observation of the phenomenon of superconductivity. The majority of chemical elements become superconducting at sufficiently low temperature. When resistance falls to zero, a current can circulate inside the material without any dissipation of energy. Secondly, provided they are sufficiently weak, external magnetic fields will not penetrate the superconductor, but remain at its surface.

This field expulsion phenomenon is known as the Meissner effect, after the physicist who first observed it in This website uses cookies so that we can provide you with the best user experience possible. Cookie information is stored in your browser and performs functions such as recognising you when you return to our website and helping our team to understand which sections of the website you find most interesting and useful.

Top Menu. Superconductor applications: Immense promise for the future Superconductors, which offer no resistance to electrical current and can repel magnetic fields, hold immense promise for future applications.

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