Superconductivity is the set of physical properties observed in certain materials, wherein electrical resistance vanishes and from which magnetic flux fields are expelled. Any material exhibiting these properties is a superconductor. Unlike an ordinary metallic conductor, whose resistance decreases gradually as its temperature is lowered even down to near absolute zero, a superconductor has a characteristic critical temperature below which the resistance drops abruptly to zero. An electric current through a loop of superconducting wire can persist indefinitely with no power source.
Most of the physical properties of superconductors vary from material to material, such as the heat capacity and the critical temperature, critical field, and critical current density at which superconductivity is destroyed. On the other hand, there is a class of properties that are independent of the underlying material. For instance, all superconductors have exactly zero resistivity to low applied currents when there is no magnetic field present or if the applied field does not exceed a critical value. The existence of these “universal” properties implies that superconductivity is a thermodynamic phase, and thus possesses certain distinguishing properties which are largely independent of microscopic details.
This is the world in which room-temperature superconductors are a reality. So far, this is a dream of the future, but scientists are closer than ever to achieving room-temperature superconductivity. A room temperature superconductor (RTS) is a type of high-temperature superconductor (high-Tc or HTS) that operates closer to room temperature than to absolute zero. However, the operating temperature above 0 °C (273.15 K) is still well below what most of us consider “normal” room temperature (20 to 25 °C). Below the critical temperature, the superconductor has zero electrical resistance and expulsion of magnetic flux fields. While it’s an over simplification superconductivity may be thought of as a state of perfect electrical conductivity. High-temperature superconductors exhibit superconductivity above 30 K (−243.2 °C). While a traditional superconductor must be cooled with liquid helium to become superconductive, a high-temperature superconductor can be cooled using liquid nitrogen. A room-temperature superconductor, in contrast, could be cooled with ordinary water ice.
According to Arun Bansil, a distinguished professor of Physics at The Northeastern University in Communications Physics, a Nature publication, his colleagues and he described a discovery that brings us closer to that elusive feat—what he described as the “holy grail” of the field. For the first time, researchers were able to model the behaviour of electrons, which are responsible for superconductors’ ability to conduct electricity. Understanding this puzzling phenomenon, Bansil said, “could be the critical step necessary toward designing superconductors that work at room temperature.”
Saloni Sharma
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