Nav: Home

When crystal vibrations' inner clock drives superconductivity

November 09, 2016

Superconductivity is like an Eldorado for electrons, as they flow without resistance through a conductor. However, it only occurs below a very low critical temperature. Physicists now believe they can enhance superconductivity - the idea is to externally drive its underlying physical phenomena by changing how ions vibrating in the crystal lattice of the conductor material, called phonons, interact with electron flowing in the material. Andreas Komnik from the University of Heidelberg and Michael Thorwart from the University of Hamburg, Germany, adapted the simplest theory of superconductivity to reflect the consequences of externally driving the occurrence of phonons. Their main result, published in EPJ B, is a simple formula explaining how it is theoretically possible to raise the critical temperature using phonon driving.

The authors studied the all-important autocorrelation function of phonons in the superconductivity BCS theory, named after John Bardeen, Leon Cooper and John Robert Schrieffer. Superconductivity is induced by phonons cooperating to bring the electrons together in the so-called Cooper pairs -- against their spontaneous tendancy to repel each other. In this work, the authors focused on the scenario of an X-ray light field rattling the phonons. They realised that a kind of driving, which controls the frequency of vibration of the lattice sites, can profoundly change the pairing of the electrons.

However, electrons and phonons do not follow the same internal clock. This means that change at what is perceived as a normal pace for phonons comes across as extremely slow to electrons. To eliminate this discrepancy, the author devised a solution based on bringing a clever time-averaging procedure into the BCS equations. This theoretical approach, the authors found, reveals the controlled elevation of the critical temperature. They thus managed to integrate the external phonon drive into the standard BCS theory. The advantge is that the critical temperature can be computed from this simple formula and can, in theory, be considerably elevated using the driving procedure. Suprisingly, the critical temperature was even higher up when further refinment to the equations accounted for phonon-phonon interactions.

A. Komnik and M. Thorwart (2016), BCS theory of driven superconductivity, Eur. Phys. J. B 89:244, DOI: 10.1140/epjb/e2016-70528-1


Related Superconductivity Articles:

Stressing metallic material controls superconductivity
No strain, no gain -- that's the credo for Cornell researchers who have helped find a way to control superconductivity in a metallic material by stressing and deforming it.
First report of superconductivity in a nickel oxide material
Scientists at SLAC and Stanford have made the first nickel oxide material that shows clear signs of superconductivity - the ability to transmit electrical current with no loss.
A hallmark of superconductivity, beyond superconductivity itself
Physicists have found 'electron pairing,' a hallmark feature of superconductivity, at temperatures and energies well above the critical threshold where superconductivity occurs.
Manipulating superconductivity using a 'mechanic' and an 'electrician'
Strongly correlated materials can change their resistivity from infinity to zero with minute changes in conditions.
Triplet superconductivity demonstrated under high pressure
Researchers in France and Japan have demonstrated a theoretical type of unconventional superconductivity in a uranium-based material, according to a study published in the journal Physical Review Letters.
The mechanism of high-temperature superconductivity is found
Russian physicist Viktor Lakhno from Keldysh Institute of Applied Mathematics, RAS considers symmetrical bipolarons as a basis of high-temperature superconductivity.
Superconductivity is heating up
Theory suggests that metallic hydrogen should be a superconductor at room temperature; however, this material has yet to be produced in the lab.
Light pulses provide a new route to enhance superconductivity
Scientists have shown that pulses of light could be used to turn materials into superconductors through an unconventional type of superconductivity known as 'eta pairing.'
Graphene on the way to superconductivity
Scientists at HZB have found evidence that double layers of graphene have a property that may let them conduct current completely without resistance.
New quantum criticality discovered in superconductivity
Using solid state nuclear magnetic resonance (ssNMR) techniques, scientists at the U.S.
More Superconductivity News and Superconductivity Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.