Superconductivity breakthroughs: Cuprates earn their stripes

March 19, 2015
Superconductivity breakthroughs: Cuprates earn their stripes
Sketch of the static patterns for (a) 1D stripy charge order and for (b) 2D checkerboard charge order, within the 2D Cu-O plane.

The Canadian research community on high-temperature superconductivity continues to lead this exciting scientific field with groundbreaking results coming hot on the heels of big theoretical questions.

The latest breakthrough, which will be published March 20 in Science, answers a key question on the microscopic electronic structure of cuprate superconductors, the most celebrated material family in our quest for true room-temperature .

This result is the product of a longstanding close collaboration between the University of British Columbia Quantum Matter Institute and the Canadian Light Source. In fact, this is the third Science paper to come out of this remarkably fruitful collaboration this past year, and the first to feature an all-Canadian effort.

The collaborators work at the forefront of research into high-temperature superconductors, an exciting class of materials exhibiting superconductivity at temperatures as comparatively warm as -100 C. As frigid as such temperature may sound, it outperforms by far traditional superconductors, which operate at closer to -270 C, or a few degrees from absolute zero - the point where all motion stops."

In the , electricity flows with absolutely no resistance, which means no energy is lost and no heat is generated. Combined, these properties allow for large 'supercurrents' that could not be realized in ordinary wires.

For this reason, are already used to provide the large magnetic fields needed for Magnetic Resonance Imaging, but the cooling systems needed to make them work are costly and impede other potential uses. Some of the major, transformative applications of room-temperature superconductivity include magnetic levitation trains and lossless power lines. (Imagine getting rid of that pesky delivery charge on your energy bill—room temperature superconductivity could make it possible.)

The paper's lead author, Riccardo Comin, a UBC graduate from Andrea Damascelli's group and now a post-doctoral fellow at the University of Toronto, compares the movement of electrons in a superconductor to birds flying in formation, coherently and without collisions. In physics-speak, the electrons move coherently and in phase, and no energy is lost as they drift smoothly along.

In , another state blocks and interacts with superconductivity: the charge-density-wave, in which the electrons assume a static pattern, different from the pattern that the material's crystal structure defines.

You can also think of the superconducting electrons like cars on a highway, all moving the same speed and direction, the picture of efficiency. But the charge-density-wave state acts like a patterned traffic jam: no movement, anywhere.

Understanding what causes this pattern is thought to be a key step to understanding superconductivity, but even pinning down the nature of the pattern has been elusive. Major theoretical models predict either a parallel line structure, or a checkerboard pattern. Unfortunately, even with advanced synchrotron techniques, it has proved impossible to see the difference between the two models.

That is, until Comin's latest results in Science, which show that the cuprate superconductor in question has a stripe-like pattern rather than a checkerboard one. The UBC-CLS team used an unconventional experimental approach to reconstruct a 2-dimensional model of the static electron pattern from 1-dimensional scans—much like the tomographic reconstructions used for medical purposes.

These results offer new fundamental insights helping hone the search for . However, more challenging questions remain. Among these puzzles: What is the driving force behind the tendency of electrons to move together coherently in the superconducting state, and how can the superconductivity transition temperature be further enhanced? Despite almost 30 years of history, the field of is more alive than ever.

Explore further: Charge instability detected across all types of copper-based superconductors

More information: "Broken translational and rotational symmetry via charge stripe order in underdoped YBa2Cu3O6+y" : www.sciencemag.org/lookup/doi/ … 1126/science.1258399

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hillmeister
3.7 / 5 (3) Mar 19, 2015
Another step to room temperature superconductivity! :D
Dethe
1 / 5 (7) Mar 19, 2015
Dethe
1 / 5 (5) Mar 19, 2015
show that the cuprate superconductor in question has a stripe-like pattern rather than a checkerboard one
Well, it's not quite a new finding, if we take a look at the pictures of cuprate stripes, which are available on the web....... Lets say, that the physicists rather invented a new way, how to interpret it. The physicists would need lotta such a "breakthroughs" for to interpret and replicate Joe Eck's findings.
PhysicsMatter
not rated yet Mar 20, 2015
What is needed is completely new theory of conductivity. The explanations of coherent movement of electrons in superconducting materials relate to quantum effect contradictory with research in cold collisionless superconducting plasma where inspite of complete lack of collisions coherent electron fluxes are "heated" through electron-beam instabilities (wave-particle interactions) producing effect of anomalous resistivity in classical sense.
It is important research with enormous potential benefits for society and needs to be funded.
bubsir
not rated yet Mar 21, 2015
We have an evidence of http://www.superc..._SC.htm.

Extraordinary claims require extraordinary evidence. Any peer reviewed work?

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