Evrim Yazgin
Cosmos science journalist
Physicists have produced a superconductor which could help achieve room-temperature operations which would be useful in applications like medicine, transportation and lossless power transmission.
The new California Institute of Technology superconductor has stronger superconductivity in some areas and weaker in others.
Superconductivity is a quantum state where metals can conduct electricity with no resistance. It is already used to for powerful magnets in MRI machines.
The main drawback of superconductors is that the only materials known to achieve superconductivity require temperatures at extremely low temperatures within just a few tens of degrees above absolute zero (-273.15°C or -459.67°F.)
It costs a lot of money and energy to keep superconductors at such low temperatures. And the few superconductors which have been shown to operate at room temperature require immense pressures – another drain on dollars and power.
In normal metals, electrons move freely through a lattice of positively-charged ions made up of protons and neutrons. When the electrons bump into the ions, they lose energy. This is what physicists call resistance.
In superconductors, on the other hand, the electrons are weakly attracted to each other and bind together to form ‘Cooper pairs.’ Within small energy ranges, called energy gaps, the electrons remain paired and don’t lose energy when they collide with the ions.
The energy gap in a superconductor is usually the same everywhere in the material.
In the 1960s, physicists wondered whether some superconducting materials could have stronger energy gaps in some areas, and weaker in others.
The new Caltech research, published in Nature, has produced such modulation in flakes of an iron-based superconductor.
The modulation of the energy gap is at the scale of the space between the atoms in the material.
The researchers have named the new modulated state a Cooper-pair density modulation (PDM) state. Their modulation means the energy gap within the superconductor is up to 40% stronger in some areas.
“The observed gap modulation represents the strongest reported so far, leading to the clearest experimental evidence to date that gap modulation can exist even at the atomic scale,” says lead author Lingyuan Kong.
Kong’s team’s discovery was made possible by the first successful scanning tunnelling microscopy of an iron-based superconductor. This kind of microscopy works by moving a very sharp metal wire tip over a surface to reveal the surface’s structure at the atomic scale.
