Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bending the rules

30.06.2014

A UCSB postdoctoral scholar in physics discovers a counterintuitive phenomenon: the coexistence of superconductivity with dissipation

For his doctoral dissertation in the Goldman Superconductivity Research Group at the University of Minnesota, Yu Chen, now a postdoctoral researcher at UC Santa Barbara, developed a novel way to fabricate superconducting nanocircuitry. However, the extremely small zinc nanowires he designed did some unexpected — and sort of funky — things.

Chen, along with his thesis adviser, Allen M. Goldman, and theoretical physicist Alex Kamenev, both of the University of Minnesota, spent years seeking an explanation for these extremely puzzling effects. Their findings appear this week in Nature Physics.

"We were determined to figure out how we could reconcile the strange phenomena with the longstanding rules governing superconductivity," said lead author Chen. "The coexistence of superconductivity with dissipation, which we observed, is counterintuitive and bends the rules as we know them."

Typically superconductivity and dissipation are thought to be mutually exclusive because dissipation, a process in thermodynamic systems whereby electric energy is transformed into heat, is a feature of a normal — versus a superconductive — state.

"But we discovered that superconductivity and dissipation can coexist under rather generic conditions in what appears to be a universal manner," Chen said.

After long and careful work, which involved both experimental and theoretical efforts, the researchers found an explanation that fits. Behind all of the observed phenomena is a peculiar nonequilibrium state of quasiparticles — electron-like excitations that formed in the nanowires Chen designed.

The quasiparticles are created by phase slips. In a superconductive state, when supercurrent flows through the nanowire, the quantum mechanical function describing the superconductivity of the wire evolves along the length of the wire as a spiral shaped like a child's Slinky toy. From time to time, one of the revolutions of the spiral contracts and disappears altogether. This event is called a phase slip. This quirk generates quasiparticles, giving rise to a previously undiscovered voltage plateau state where dissipation and superconductivity coexist.

"The most significant achievement was making the nanowires smaller and cooler than anyone had done previously," Kamenev said. "This allowed the quasiparticles to travel through the wire faster and avoid relaxation. This leads to a peculiar nonthermal state, which combines properties of a superconductor and a normal metal at the same time."

In addition to discovering this unique phenomenon, the team also found another heretofore-unseen property in the voltage plateau. When a magnetic field is turned on in the voltage plateau state, rather than shrinking the superconducting region, which is what would usually occur, the superconducting area expands and is enhanced.

"This is an unexpected property of very small nanowires," said Goldman.

This state appears to be universal for ultra-small superconducting circuitry like Chen's, which features ideal contacts between the nano-elements and the leads. Such nanoscale superconductors may be key components in future superconducting computer systems.

"Our findings demonstrate that superconducting nanocircuits can be used as a simple, but rather generic platform to investigate nonequilibrium quantum phenomena," Chen concluded.

"Now we need to explore the parameters of nanowires that give rise to the effect and those that don't," Goldman said. "We also need to examine the behavior of wires of different lengths and different materials in order to further define the parameters."

Julie Cohen | Eurek Alert!

Further reports about: explanation generic nanowires nonequilibrium parameters phenomena rise superconductivity voltage

More articles from Physics and Astronomy:

nachricht Kiel physicists discover new effect in the interaction of plasmas with solids
16.01.2019 | Christian-Albrechts-Universität zu Kiel

nachricht Understanding insulators with conducting edges
16.01.2019 | Goethe-Universität Frankfurt am Main

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Flying Optical Cats for Quantum Communication

Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.

In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...

Im Focus: Nanocellulose for novel implants: Ears from the 3D-printer

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

Im Focus: Elucidating the Atomic Mechanism of Superlubricity

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...

Im Focus: Mission completed – EU partners successfully test new technologies for space robots in Morocco

Just in time for Christmas, a Mars-analogue mission in Morocco, coordinated by the Robotics Innovation Center of the German Research Center for Artificial Intelligence (DFKI) as part of the SRC project FACILITATORS, has been successfully completed. SRC, the Strategic Research Cluster on Space Robotics Technologies, is a program of the European Union to support research and development in space technologies. From mid-November to mid-December 2018, a team of more than 30 scientists from 11 countries tested technologies for future exploration of Mars and Moon in the desert of the Maghreb state.

Close to the border with Algeria, the Erfoud region in Morocco – known to tourists for its impressive sand dunes – offered ideal conditions for the four-week...

Im Focus: Programming light on a chip

Research opens doors in photonic quantum information processing, optical signal processing and microwave photonics

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new integrated photonics platform that can...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Our digital society in 2040

16.01.2019 | Event News

11th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Aachen, 3-4 April 2019

14.01.2019 | Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

 
Latest News

Artificially produced cells communicate with each other: Models of life

17.01.2019 | Life Sciences

Velcro for human cells

16.01.2019 | Life Sciences

Kiel physicists discover new effect in the interaction of plasmas with solids

16.01.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>