Pairs of Cooper Pairs…

New state of matter: The team observed electron quadruplets in this iron-based superconductor material, seen mounted for experimental measurements. (Courtesy: Vadim Grinenko, Federico Caglieris)

Topics: Condensed Matter Physics, Solid-State Physics, Superconductors

Note: I gave my research proposal last Friday. I have been answering some concerns about my proposal for the committee. I followed the outline sent to me by my advisor. I hope I’ve answered them sufficiently. I will post today and tomorrow; next week on Monday, Wednesday, and Friday. I tutor Calculus. For a person finished with classes, I’m extremely busy.

Cool a material below its superconducting transition temperature and you’d expect it to start conducting electricity without resistance and expelling magnetic fields. But an international group of physicists has found that a certain kind of iron-based material doped with negative charges does the opposite at around the same temperature – producing spontaneous magnetic fields and retaining resistance when chilled. The researchers say that the results point to a new state of matter in which electrons flow in correlated groups of four, rather than two.

According to the Bardeen-Cooper-Schrieffer (BCS) theory, superconductivity occurs when electrons get together to form what is known as Cooper pairs. Whereas in a vacuum two electrons would repel each other, when moving through the crystal lattice of a superconducting material, one of these particles shifts the positions of surrounding atoms to leave a small region of positive charge. This attracts the second electron to create the pair.

The creation of many such pairs yields a collective condensate, which results in frictionless electron flow. This occurs below a certain temperature – the superconducting transition temperature (Tc) – at which point atoms lack the thermal energy to break up the pairs.

Superconductor reveals new state of matter involving pairs of Cooper pairs, Edwin Cartlidge, Physics World

Published by reginaldgoodwin

Engineering Physics, Bachelors of Science, December 1984 Microelectronics & Photonics, Graduate Certificate, February 2016 Nanoengineering, Masters, December 2019 Nanoengineering, Ph.D., December 2021

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