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Laser Light Stimulates Iron Compound to Transmit Power Without Resistance

Scientists have been successful for the first time in using laser pulses to stimulate an iron-based compound into a superconducting state. This implies that the compound conducted electricity without resistance.

Visualizations of electron energies as the experiment ran. (Image credit: © 2019 Suzuki et al.)

Although the iron compound is a recognized superconductor at ultralow temperatures, this technique allows superconduction at higher temperatures. It is expected that this type of research could significantly enhance power efficiency in electronic devices and electrical equipment.

Put simply, we demonstrated that under the right conditions, light can induce a state of superconductivity in an iron compound. So it has no resistance to an electric current. In the past it may even have been called alchemy, but in reality we understand the physical processes that instantly changed a normal metal into a superconductor. These are exciting times for physics.

Takeshi Suzuki, Project Researcher, Institute for Solid State Physics, University of Tokyo

Superconduction is currently a topic of interest in solid state physics, or rather a very, very cold one. Suzuki described that superconduction is when a material, mostly an electrical conductor, conducts an electric current but does not add to the resistance of the circuit.

If this can be achieved, it would mean devices and infrastructure based on such concepts could be highly power efficient. Simply put, in the near future, it could save money on an electricity bill.

However, right now, there is a catch as to why superconductor-based televisions and vacuum cleaners have not yet made it to the stores. The researchers analyzed materials like iron selenide (FeSe) and found that they superconduct only at temperatures far below the freezing point of water.

Actually, at ambient pressure, FeSe typically superconducts at about 10 degrees above absolute zero, or about −263 °C, barely warmer than the cold, dark depths of space.

Although FeSe can be coaxed into superconduction at marginally less challenging temperatures of up to about −223 °C, this necessitates huge pressures to be used on the sample, which is about six gigapascals or 59,000 times standard atmosphere at sea level. That would turn out to be unfeasible for the execution of superconduction into useful devices.

Consequently, this poses a challenge to physicists, although this challenge serves to inspire them as they aim to one day be the first to deliver a room-temperature superconductor to the world.

Every material in our daily lives has its own character. Foam is soft, rubber is flexible, glass is transparent and a superconductor has a unique trait that current can flow smoothly with no resistance. This is a character we would all like to meet.

Mari Watanabe, Graduate Student, Institute for Solid State Physics, University of Tokyo

Mari Watanabe continued, “With a high-energy, ultrafast laser, we successfully observed an emergent photo-excited phenomenon—superconduction—at the warmer temperature of minus 258 degrees Celsius, which would ordinarily require high pressures or other impractical compromises.”

This study is the most recent in a long series of steps from the discovery of superconduction to the long-anticipated day when a room-temperature superconductor may become a reality. Moreover, similar to various upcoming fields of study within physics, there may be applications that have not yet been visualized.

One likely application of this concept of photo-excitation is to realize high-speed switching components for computation, which would also generate some heat, thus enhancing the efficiency.

Next, we will search for more favorable conditions for light-induced superconductivity by using a different kind of light, and eventually achieve room-temperature superconductivity.

Takeshi Suzuki, Project Researcher, Institute for Solid State Physics, University of Tokyo

Takeshi Suzuki concluded, “Superconductivity can dramatically reduce waste heat and energy if it can be used in everyday life at room temperature. We are keen to study superconductivity in order to solve the energy problem, which is one of the most serious problems in the world right now.”


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