The first metamaterial superconductor: One step closer to futuristic physics-defying contraptions

In the realms of electronics, magnetism, and quantum mechanics, superconductivity has an almost mythical status. Some materials, when cooled to a critical temperature, electrical resistance instantly drops to zero and magnetic fields are completely ejected (see video below). Superconducting magnets are already used in MRI machines and particle accelerators like CERN’s LHC, and are being considered for advanced maglev trains. Zero electrical resistance means that a current can flow around a superconducting coil indefinitely (at least 100,000 years) without any applied voltage — a feature that could completely revolutionize power distribution, power storage, electric motors, computers, and more.

The problem is, the hottest superconductor yet discovered still needs to be cooled to around -140 Celsius (133 Kelvin, -220 Fahrenheit) — and cryogenic cooling just isn’t feasible for everyday use. Now, however, some US researchers may have unearthed the secret of room-temperature superconductors: Building your own metamaterial superconductor from scratch.

As we’ve covered before, metamaterials are human-made materials that have alien, not-seen-in-nature properties. The most common example is negative refraction: In nature, every known material has a positive refractive index (it always bends light a certain way) — while metamaterials can bend light in the opposite direction. These materials have led to some interesting applications, such as invisibility cloaks. Now, researchers at Towson University, the University of Maryland, and the Naval Research Laboratory have done the same thing with superconductors: They’ve tweaked a compound in the lab, metamaterial-style, to raise its critical temperature. This empirical, deliberate approach is very different from usual superconductor research, which is mostly bested on educated guesswork. [arXiv:1408.0704  "Experimental demonstration of superconducting critical temperature increase in electromagnetic metamaterials"]

Various superconductors and their critical temperatures

In theory, this is a very big step towards creating one of the most powerful, valuable, and elusive materials in the world: a room-temperature superconductor. While superconductors are already used extensively in science and medicine, the fact that they need to be kept at cryogenic (below -150C) temperatures makes them very expensive and unwieldy. A lot of work is being done into so-called “high-temperature superconductivity,” but the best anyone has managed is a critical temperature of -140C — HgBa₂Ca₂Cu₃O_x (HBCCO) in case you were wondering.

Read our featured story: The wonderful world of wonder materials

In practice, the researchers still have a long way to go: Their metamaterial-like approach was able to raise the critical temperature of tin by 0.15 Kelvin. Still, in the realm of quantum mechanics where almost nothing is known about why or how superconductivity exists in the first place, it’s big news. We especially know very little about high-temperature superconductors – we think the “layers” of these complex compounds act like the electron equivalent of optical waveguides, steering electrons through the material with zero resistance. This new research might help us understand these high-temperature superconductors a little better, and maybe also to tweak them to move the critical temperature ever closer to room temperature.

A prototype superconducting power cable — awesome, but commercially unfeasible as it requires constant liquid nitrogen cooling.

If we can eventually master superconductors — and there’s every reason to believe that we can — then we can expect many facets of life to change very rapidly. Superconducting power lines could save billions of dollars in transmission losses — or allow for the building of world-spanning super grids. We could replace every transport system with cheap, super-fast maglev trains. It might even allow for cloaking devices… and I assure you, that’s just the beginning!

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