To diversify the applications of superconductors that currently operate at chilly temperatures below 135 kelvin (K), scientists are searching for new classes of superconducting materials that will show this property at warmer temperatures.
Now, a research team in Japan has synthesized a promising new class of superconductors, made of Hg0.44ReO3, where an unusual motion of the mercury (Hg) atoms enhances superconducting properties at temperatures up to 7.7 K.
The Dutch physicist Heike Kamerlingh Onnes discovered superconductivity one hundred years ago, when he noticed that the electrical resistance of mercury dropped to zero suddenly at 4.2 K. Superconducting materials are now used routinely in magnetic resonance imaging scanners.
In classical superconductors such as mercury, superconductivity arises through the combined vibrations of the atoms in the crystal. This makes the crystal structure a key factor for the superconducting properties of a material. In the case of HgxReO3, the atomic structure consists of rhenium (Re) and oxygen (O) building blocks. In the empty spaces between them, the mercury atoms arrange in chains (Fig. 1). However, some of the available places along these chains lack mercury atoms, and the team’s work suggests that this leads to an arrangement of paired mercury atoms.
"These pairs move within the channel in an oscillatory motion known as rattling", explains team-member Ayako Yamamoto from the RIKEN Advanced Science Institute in Wako. The rattling vibrations provide a strong feedback for the electrons, and therefore reinforce superconductivity in the material. In comparison to a similar structure lacking mercury pairs, the superconducting temperature of Hg0.44ReO3 at 7.7 K is almost twice as high. "Despite remaining below the present record of 135 K for a superconductor, there is potential for improving operation temperatures", says Yamamoto. “The application of pressure increases the superconducting temperature to 11.1 K, and this could mean that for the right crystal structure further enhancement is possible.”
Yamamoto and her colleagues are now working to optimize the crystal structure further—for example, by replacing rhenium with other elements. A better understanding of the influence of the mercury atoms’ rattling motion may also provide better insight into the mechanism of superconductivity in such structures. “Mercury seems to be a magic element in superconductivity, not only for its role in Kamerlingh Onnes’ discovery, but also for the fact that mercury is part of the material with the highest known superconducting temperature, HgBa2Ca2Cu3Ox,” Yamamoto explains. "Once more, mercury is playing a key role for new superconductors," she says.
The corresponding author for this highlight is based at the Magnetic Materials Laboratory, RIKEN Advanced Science Institute
 Ohgushi, K., Yamamoto, A., Kiuchi, Y., Ganguli, C., Matsubayashi, K., Uwatoko, Y. & Takagi, H. Superconducting phase at 7.7 K in the HgxReO3 compound with a hexagonal bronze structure. Physical Review Letters 106, 017001 (2011).
gro-pr | Research asia research news
New type of smart windows use liquid to switch from clear to reflective
14.12.2017 | The Optical Society
New ultra-thin diamond membrane is a radiobiologist's best friend
14.12.2017 | American Institute of Physics
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
14.12.2017 | Health and Medicine
14.12.2017 | Physics and Astronomy
14.12.2017 | Life Sciences