Experiment hints at a new way to engineer high temperature superconductors
Superconductors are among the wonders of modern science. They allow a current to flow with zero resistance in materials cooled below some critical temperature. Superconductors are the crucial ingredients in everything from high-power magnets and MRI machines to highly sensitive magnetometers and magnetic levitation devices.
One problem though is that superconductors work only at very low temperatures. So one of the great challenges in this area of science is to find materials that superconduct at higher temperatures, perhaps even at room temperature. That won’t be easy given that the current record is around 150 kelvin (-120 degrees centigrade).Nevertheless, a way of increasing the critical temperature of existing superconducting materials would be hugely useful.
Today, a group of physicists and engineers say they have worked out how to do this. The trick is to think of a superconductor as a special kind of metamaterial and then to manipulate its structure in a way that increases its critical temperature.
Vera Smolyaninova at Towson University in Maryland and colleagues from the University of Maryland and the Naval Research Laboratory in Washington DC, have even demonstrated this idea by increasing the critical superconducting temperature of tin.
First some background about metamaterials. Until relatively recently, physicists had always treated bulk materials as homogeneous lumps of the same stuff. These lumps have bulk properties such as the ability to bend light in a certain way.
But in recent years they have began to think about constructing artificial materials made of periodic patterns of structures that themselves interact with electromagnetic waves, things like wires, c-shaped conductors and so on. If these structures are much smaller than the wavelength of the light passing by, then they act like a homogeneous lump, at least as far as the light is concerned.
By toying with this periodic structure, physicists can create artificial materials with all kinds of exotic properties. The most famous of these is the invisibility cloak, a metamaterial designed to steer light around an object as if it were not there.
Superconductivity can be thought of in a similar way, say Smolyaninova and co. Conventional superconductors made of a single metal are homogeneous lumps of the same stuff that have zero resistance at some critical temperature…..
… read more at medium.com