Superconductivity can't be avoided when electrons couple up. Normally, electrons can't overlap, but Cooper pairs act like particles of light, any number of which can pile onto the head of a pin. A Cooper pair merging into a single quantum mechanical state that is oblivious to the atoms it passes between is called asuperfluid.
The theory explains why mercury and other metallic elements superconduct above a few kelvins. The feeblest of glues are made from atomic ripples. It jiggles atoms when the heat is turned up.
The stronger electron glue in cuprates was discovered by IBM researchers in 1986. Researchers found others that superconduct above 100 and then above 130 kelvins after observing a cuprate at 30 kelvins.
The breakthrough led to a widespread effort to understand the glue that makes high-temperature superconductivity possible. It's possible that electrons bunched together to create a patch of charge. Spin is a property of the electron that orients it in a specific direction.
Less than a year after high-temperature superconductivity was discovered, Philip Anderson came up with a theory. He said that the glue was formed by a previously described quantum phenomenon called superexchange. When electrons are able to hop between multiple locations, their position becomes uncertain. A lower energy state is what particles naturally seek out.
The electron seeks situations in which they can hop. When an electron's neighbor points up, it prefers to point down since this allows it to hop between the same atoms. Superexchange establishes a pattern of electron spin in some materials. electrons are pushed to stay a certain distance apart They can't hop if they're too far away. Anderson thought it could form strong Cooper pairs.
The material properties that they could measure, like reflectivity or resistance, offered only crude summaries of the collective behavior of trillions of electrons.
The traditional techniques of Condensed-matter physics were never designed to solve this problem.
It's a super experiment.
Davis, an Irish physicist with labs at Oxford, Cornell University, University College Cork, and the International Max Planck Research School for Chemistry and physics of quantum materials in Dresden, has developed tools to scrutinize cuprates on the atomic level. Experiments have gauged the strength of a material by chilling it until it reaches the critical temperature where superconductivity begins. The glue around individual atoms has been prodded by Davis' group.
They modified an established technique called scanning tunneling microscopy, which drags a needle across a surface to measure the current of electrons jumping between them. They measured a current of electron pairs by replacing the needle's metallic tip with a superconducting one. They could map the density of Cooper pairs around each atom. The first image of Cooper pairs was published in nature.
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