Looking to Explain Iron SuperconductorsCategory: Science & Technology
Posted: May 7, 2012 12:44PM
Superconductors are cool, literally and figuratively. These materials will conduct electricity with little or no resistance, which allows massive amounts of energy to be transmitted without any loss or very low power signals to be sent and received correctly. Making a material act as a superconductor however requires chilling it to very low temperatures. Traditional superconductors need to reach down to near absolute zero while high-temperature superconductors need to be more than hundred degrees below zero, centigrade. Scientists are constantly working to find room-temperature superconductors but the work is hindered by the fact that we do not understand what causes superconductivity.
The dominant theory for high-temperature superconductivity involves Cooper pairs. These are pairs of electrons which defy normal logic in order to flow without resistance. One would expect electrons to fly away from each other instead of pairing up, and usually they do fly away. One theory for why they do not in Cooper pairs is that the electrons are aligned in such a way as to overcome their repulsion. Even though electrons are negatively charged points in space, they still have a magnetic moment, which makes them polar like a bar magnet. If the moments are pointing in opposite directions, the electrons might be able to pair up. Proving this though is difficult.
Researchers at Brookhaven National Laboratory have recently made an important discover with regards to this theory and iron superconductors. Iron high-temperature superconductors were only discovered in 2008, and previously only copper, high-temperature superconductors were known to exist. Copper does not lend itself to testing this theory but iron, with its multiple magnetic electrons in their own energy bands, does.
The researchers had to invent a way to measure the alignment of the electrons while also measuring their conductivity, but once they had, they found the theory is not incorrect. The electrons did conduct better when they were aligned in opposite directions, as well as parallel and anti-parallel to their direction of motion. This does not mean the alignment is what directly causes Cooper pairs and superconductivity, but it is linked to them. Potentially this research could lead to the discovery and possibly the designing of future superconductors.