Featured Research

from universities, journals, and other organizations

Superconducting State Can Be Induced By High Pressure In So-called High-temperature Superconductors

Date:
May 21, 2008
Source:
Carnegie Institution
Summary:
Superconductors can convey more than 150 times more electricity than copper wires because they don't restrict electron movement, the essence of electricity. But to do this, the materials have to be cooled below a very low, so-called, transition temperature, which often makes them impractical for widespread use. Now for the first time, scientists have found that in addition to chemical manipulation, the superconducting state can be induced by high pressure in so-called high-temperature superconductors.

This graph is a 3D phase diagram which compares conditions under which the superconducting state in a bismuth-based high-temperature superconductor can be induced. The graph shows changes by “doping” (x)—the removal of an electron equivalent to addition of a “hole” or positive charge (x)—pressure (P), and temperature (T). The onset of superconductivity (pink area) and the “insulator-to-metal” transition occurs at higher doping and at higher pressure. The line at 21GPa (207,000 atmospheres) is nearly vertical, which indicates a similarity in the behaviour of electrons’ coupled spins (magnons) and units of vibration (phonons) at low and high temperatures.
Credit: Image courtesy Tanja Cuk

Superconductors can convey more than 150 times more electricity than copper wires because they don't restrict electron movement, the essence of electricity. But to do this, the materials have to be cooled below a very low, so-called, transition temperature, which often makes them impractical for widespread use. Now for the first time, scientists have found that in addition to chemical manipulation, the superconducting state can be induced by high pressure in so-called high-temperature superconductors. The discovery, published in the May 30, 2008, issue of Physical Review Letters, opens a new window on understanding and harnessing these miracle materials.

The early superconductors had to be cooled to extremely low (below 20 K or -423 F) temperatures. But in the 1980s scientists discovered a class of what they call high-temperature superconductors made of ceramic copper oxides, called cuprates. They found that at temperatures as high as about 135 K, or -216 F, these materials transition into superconductors. Understanding how they work and thus how they can be manipulated to operate at even higher temperatures is currently one of the most important unsolved problems in physics--a holy grail for many.

"In cuprate superconductors the atoms are arranged in a layered structure," explained co-author of the study, Viktor Struzhkin at the Carnegie Institution's Geophysical Laboratory. "When the material goes into the superconducting state, changes occur in the copper-oxide planes, the electron spins behave differently, the vibrational energy is altered, the charges move differently, and more."

Another co-author of the study, Alexander Goncharov, elaborated: "Over the years scientists have found that the transition temperature can be increased with a specific amount of 'doping,' which is the addition of charged particles--either negatively charged electrons or positively charged holes. We wanted to see the effects of high pressure on one bismuth-based high-temperature cuprate (Bi1.98.Sr2.06Y0.68Cu2O8+). Pressure has the added bonus that it can be applied gradually, like tuning a radio. We gradually tuned in to the superconductivity and could watch what happened over a broad range of pressures."

The scientists observed the subatomic effects on the material of pressures close to 350,000 times the atmospheric pressure at sea level (35 GPa) using a diamond anvil cell to squeeze the sample and specialized techniques, Raman spectroscopy and X-ray diffraction, to measure the changes.

"21 GPa was the magic number, or critical pressure," remarked Tanja Cuk, the lead author and a student at Stanford University, who carried out this work as part of her Ph.D. thesis research. "By compressing the structure, we were able to observe changes in six different physical properties. But even more exciting, the changes were similar to those observed when the material has been doped to its optimal level. This means that the critical pressure is likely related to doping. Plus, by finding that pressure can be used instead of temperature and doping, we've found an entirely new approach to studying what's behind superconducting properties of high-Tc superconductors."

According to Struzhkin: "This study brings us one step closer to understanding the mechanism of high-temperature superconductivity by giving a completely new perspective of the superconducting state driven by a continuous variable--pressure. It appears that superconductivity is favored on the borderline between insulating and metallic states. By applying these high pressures, we may be able to discover the missing clues to the mechanism of the high-temperature superconductivity and move a few steps closer to using superconductors in daily life. This could change our whole energy system."


Story Source:

The above story is based on materials provided by Carnegie Institution. Note: Materials may be edited for content and length.


Cite This Page:

Carnegie Institution. "Superconducting State Can Be Induced By High Pressure In So-called High-temperature Superconductors." ScienceDaily. ScienceDaily, 21 May 2008. <www.sciencedaily.com/releases/2008/05/080519150608.htm>.
Carnegie Institution. (2008, May 21). Superconducting State Can Be Induced By High Pressure In So-called High-temperature Superconductors. ScienceDaily. Retrieved September 30, 2014 from www.sciencedaily.com/releases/2008/05/080519150608.htm
Carnegie Institution. "Superconducting State Can Be Induced By High Pressure In So-called High-temperature Superconductors." ScienceDaily. www.sciencedaily.com/releases/2008/05/080519150608.htm (accessed September 30, 2014).

Share This



More Matter & Energy News

Tuesday, September 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Argentina's Tax Evaders Detected, Hunted Down by Drones

Argentina's Tax Evaders Detected, Hunted Down by Drones

AFP (Sep. 30, 2014) Argentina doesn't only have Lionel Messi the footballer, it has now also acquired "Mesi" the drone system which monitors undeclared mansions, swimming pools and soy fields to curb tax evasion in the country. Duration: 01:18 Video provided by AFP
Powered by NewsLook.com
Do Video Games Trump Brain Training For Cognitive Boosts?

Do Video Games Trump Brain Training For Cognitive Boosts?

Newsy (Sep. 29, 2014) More and more studies are showing positive benefits to playing video games, but the jury is still out on brain training programs. Video provided by Newsy
Powered by NewsLook.com
CERN Celebrates 60 Years of Science

CERN Celebrates 60 Years of Science

Reuters - Business Video Online (Sep. 29, 2014) CERN, the European Organisation for Nuclear Research, celebrates 60 years of bringing nations together through science. As Joanna Partridge reports from inside the famous science centre it's also planning to turn the Large Hadron Collider particle accelerator back on after an upgrade. Video provided by Reuters
Powered by NewsLook.com
This 'Invisibility Cloak' Is Simpler Than Most

This 'Invisibility Cloak' Is Simpler Than Most

Newsy (Sep. 28, 2014) Researchers from the University of Rochester have created a type of invisibility cloak with simple focal lenses. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins