Physicists demonstrate a way to conduct electricity between transistors without energy loss

Wednesday, August 15, 2018 by

Chinese researchers have created a new superconductor, a material that can transport electrical energy between transistors with such efficiency that there is no energy lost during the transfer. In an article in Science Daily, their discovery can lead to the development of electronics that can run on very little power and quantum computers whose speeds leave today’s supercomputers in the dust.

To make the superconductor, the researchers combined several materials in a new manner, giving them the desired magnetic and insulator properties. The process is detailed in their study, which appeared in the scientific journal Nature Physics.

The main author of the study was Weida Wu, an associate professor at Rutgers University-New Brunswick who led the effort to create the superconductor. She explained that the magnetic properties of the material were greatly reduced by the process.

Despite that, the superconductor remained capable of acting as a magnet during their experiment. More importantly, it could conduct electricity at low temperature with 100 percent efficiency.

“At least in principle, if you can make it work at a higher temperature, you can use it for electronic interconnections within silicon chips used in computers and other devices,” remarked Wu. (Related: “Smart” windows made from common glass and cheap nanocrystals.)

Quantum anomalous Hall insulator tightly regulates the movement of electrons

Wu, her study co-authors in China, and the other researchers used a combination of chromium and vanadium as the magnetic elements. Their insulator was another mixture of antimony, bismuth, and tellurium.

A thin overlayer film of chromium and vanadium were placed on top of bismuth-antimony-tellurium films. They were further capped with two nanometers of aluminum. This material was grown on a heat-treated strontium titanate substrate by using a molecular beam epitaxy system to co-evaporate it.

The treated film was carefully etched by hand into a Hall bar shape. Then it was connected to a large squarish area so that measurements could be taken using a magnetic force microscope.

To negate the possibility of electrostatic interference between the sample and the magnetic tip, 15 nanometers of gold film layer was deposited in the squarish area.

The new superconductor material is called the “quantum anomalous Hall insulator.” When electrons passing through it point in one direction, the electric current is only allowed to flow along the edges of the material in that same direction. This control over electron traffic prevents the loss of electrical energy.

At near-absolute zero, new superconductor stops energy loss in electric currents

The Chinese-developed superconductor will directly benefit all kinds of electronics. For example, the transistors of silicon chips in computers use different kinds of metals for conducting electricity.

However, these metals are nowhere as efficient as superconductors. They will lose energy during the transfer process, which reduces the capability of the electronics.

Replacing those ordinary metals with the new quantum anomalous Hall insulator will raise the efficiency levels of transistors by a significant margin. The electronics will also be able to run on lower currents.

The researchers showed off the capabilities of their new superconductor material. They reduced the temperature to minus 459.67 degrees Fahrenheit, which is close to absolute zero. At these rock-bottom temperatures, the quantum anomalous Hall insulator is capable of conducting electrical currents at 100 percent efficiency.

Wu and her teammates are planning to test their new superconductor at higher temperatures that can be more easily replicated in electronics. They will also work on a quantum computing platform that can make the most out of their quantum anomalous Hall insulator.

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