A group of researchers from the U.S. Department of Energy's Brookhaven National Laboratory, Kyoto University, Columbia Engineering and Columbia Physics has uncovered an unusual electronic state in an unconventional superconductor family.
Published in the journal Nature Communications, the researchers' work established that iron-pnictides and cuprates and titanium-oxypnictide type of superconductors have an unexpected connection. This connection gives birth to a new material family, giving scientists the opportunity to gain new understanding into the secrets involving high-temperature superconductivity.
Leading the research, Simon Billinge from the Brookhaven National Laboratory and Columbia Engineering likened their discovery to an archaeologist unearthing a new pharaoh's tomb. As the researchers tried and solved mysteries surrounding unconventional superconductors, they needed to discover new but related systems to get a more detailed picture of what is happening.
Superconductors can only function at very low temperatures so they are of no use yet for day-to-day life. High-temperature superconductors were discovered in the 1980s, allowing scientists to inch closer towards using superconductors by enabling loss-free currents to be carried across superconductive materials for more common applications.
It's a mystery how superconductors interact with each other, sometimes paring up and sometimes avoiding each other. Over time, scientists were able to detect special electronic states where the charges form stripes as well as checkerboard patterns, both of which break translational symmetry in the material or the repeated sameness across a surface. Broken rotational symmetry was also observed although changes in translational symmetry was not present, resulting in an all-white checkerboard pattern called nematic order.
With these discoveries and observations, researchers became keen on seeing whether the unusual electronic state would also be present in the high-temperature titanium-oxypnictide superconductors unveiled in 2013.
By conducting different diffraction studies, researchers sought to find the broken rotational symmetry effect. Their experiments revealed telling symmetry with distortion breaking at low temperature.
Billinge added that the capacity to quickly use multiple complementary methods of experiment were critical to the study. This could not have been achieved had the researchers not acquired the necessary knowledge and experience and collaborated together to study superconductors.
The discovery of nematic order in titanium-oxypnictides, alongside the fact that chemical and physical properties connect iron-pnictide and cuprate high-temperature superconductors, turn these materials into a special new system that will aid further research on superconductors.
Some of the supporters for this study include the DOE's Office of Science, the U.S. National Science Foundation, the Friends of Todai Inc. and the Japan Atomic Energy Agency.
