Analysing Negative Magnetoresistance Metals

Superconducting materials are quite unique for the obvious reason that they are a superconductor. But many materials that have superconducting qualities also have other unique features relating to their nano scale structure. One of these effects is called magneto transport. This is when an exterior magnetic field is applied to a metal and it shunts electrons through the material resulting in a current flowing. The resistance that the metal provides against this current is called magnetoresistance. Of course, superconductors aren’t exactly known for putting up much resistance to current and so in some unique cases they are described as having a negative magnetoresistance. Normally the Meissner effect will produce conflicting current in the superconductor and so the resistance will end up increasing as the magnetic field strength increases. However when very thin and narrow strips of superconductors are only probed with a weak magnetic field the Meissener effect is reduced and the resistance vanishes. There is currently no accurate description of exactly what occurs and so research has recently been performed on indium oxide (In2O3) wires in order to come to gather more data as most experiments so far have been done lead (Pb) and aluminium (Al) leaving quite a lot questions unanswered. The experiment on the indium oxide has so far managed to prove that the negative resistance was found to be heavily based on the magnetic field applied, no surprise there, but also upon the width of the wire completely irrespective of its length. There is still quite a way to go until a quantitative theory can be developed to explain and predict the nature of the superconducting materials but this research is a massive step along the way.


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