The era of supercurrent transistors has begun thanks to an important research
Making transistors from superconducting materials is now possible. This was shown in an important study conducted by scientists from the National Institute for Nanoscience of the National Research Council-CNR-NANO in Pisa, with contribution by the SuPerconducting and other INnovative materials and devices institute-CNR-SPIN.
The study, published in the journals Nature Nanotechnolgy, NanoLetters and Nature Electronics, opens the era of supercurrent transistors and denies some assumptions of the theory of superconductivity, so far indisputable.
The researchers have discovered that it is possible to use an electrical field to enable or inhibit the passage of supercurrent through a superconducting wire.
“In theory, an electrostatic field has no effect on a superconducting metal, but this idea was refuted when we discovered that an intense electric field can extraordinarily affect a superconductor and be used to control supercurrent that passes through it, even 'turning off' superconductivity completely, if it is sufficiently intense”, said Francesco Giazotto from CNR-NANO and Scuola Normale Superiore, who led the research.
This is an important result that researchers obtained by applying intense electric fields to superconducting transistors made of a thin film of superconducting material, specifically titanium or aluminum. Thanks to a special instrument developed by CNR-NANO in Pisa and available in a very small number of labs across the world, the researchers could make the delicate electric measures at temperatures near absolute zero.
“From the perspective of fundamental physics, these results suggest that there are some aspects of superconductivity still to be understood and invite to re-think some aspects of the theory that did not consider the so-called 'field effect’ for superconductors. In the meanwhile, we are already working to understand the microscopic origin of the effect we have observed”, said the researcher.
The phenomenon observed could be applied to innovative devices and quantum technologies. In particular, the research preludes to the development of transistors fully based on superconducting materials rather than on semiconductors, such as silicon, currently used in this type of devices.
“With regard to applications, this effect could revolutionize electronics with newly-conceived devices, including fully metallic superconducting transistors, i.e. circuits with a very reduced consumption of energy and heating, which are also technically easy to develop and based on common materials, such as titanium and aluminum, at low cost and scalable for industrial processes. This could also lead to new architectures for advanced quantum technologies”, concluded Giazotto.
The main advantage of superconductors is the possibility to conduct current without dispersing energy, since when they are cooled below a critical temperature their electric resistance become null.