Superconductivity promises to transform everything from power grids to personal electronics. Yet getting the low-waste form of power to operate at ambient temperatures and pressures is proving to be easier said than done.
A discovery by a team of researchers from Emory University and Stanford University in the US could inform theories that might help us get around the stumbling blocks.
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The finding involves what's known as oscillating superconductivity. Typical superconductor behaviors involve electron partnerships called Cooper pairs moving through materials without losing significant amounts of energy in the form of heat.
Cooper pairs in oscillating superconductivity happen to move in a kind of wave-like dance. While rarer than 'normal' superconductivity, the oscillations occur at relatively warmer temperatures, making the phenomenon interesting to scientists wanting to make superconductivity happen consistently at room temperature.
"We discovered that structures known as Van Hove singularities can produce modulating, oscillating states of superconductivity," says physicist Luiz Santos, from Emory University in the US.
"Our work provides a new theoretical framework for understanding the emergence of this behavior, a phenomenon that is not well understood."
These Van Hove singularities are particular structures that occur in some materials, inside which the energy of electrons can go through unusual changes. This can have a big impact on how the material reacts to outside forces, and how it conducts electricity.
In this study, the team modeled Van Hove singularities in a new way. The results of the modeling suggested that in certain scenarios, these specific structures might lead to oscillating superconductivity, potentially giving us new ways to manage it or to initiate it.
This is all high-level physics, and only theoretical for the time being, but it improves our understanding of superconductivity at temperatures around three times as cold as a standard kitchen refrigerator – still chilly, but at levels that could be generally managed.
There's some serious debate over whether superconductivity has been achieved at room temperature, but it certainly isn't yet accessible in a way that makes it viable to use outside of a lab or in bulky, expensive equipment.
Superconductivity was discovered in 1911 by Dutch physicist Heike Kamerlingh Onnes in tests on mercury, but it wasn't until 1957 that scientists understood the how and the why of what was happening. Since then, we've found out much more about the phenomenon, including how it can come in an oscillating form.
The hope is one day that we'll be moving electricity around much more efficiently and cheaply. The ability of superconductors to create super-strong magnetic fields is already being put to good use: in MRI machines, in maglev trains, and at the Large Hadron Collider.
"I doubt that Kamerlingh Onnes was thinking about levitation or particle accelerators when he discovered superconductivity, but everything we learn about the world has potential applications," says Santos.
The research has been published in Physical Review Letters.
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