Kosmas Prassides of Tohoku University, a post-doctoral researcher who just joined the faculty, has led a team that discovered a new state of matter called the ‘Jahn-Teller-metal’ that has some unique features — an insulator, superconductor, metal and magnet — all-in-one metal.
Essentially, the new matter ‘Jahn-Tellar-metal’ is useful as superconductors at very high temperatures, a deadly combination for future research i physics.
The study involving an international team, made the discovery from a superconductor made from carbon-60 molecules or “buckyballs” that turned into a new matter after chaning the distance between buckyballs with rubidium.
Since the material has a rich combination of insulating, magnetic, metallic and superconducting phases – including the unknown new state, “Jahn–Teller metal”.
The study was based on observing how the interplay between the electronic structure of the molecules and their spacing within the lattice can strengthen interactions between electrons that cause superconductivity.
Superconductors are a large and diverse group of materials that offer zero resistance to electrical currents when cooled below a critical temperature (Tc).
The abstract of their study says that it is difficult to understand the relationship between the superconducting, the neighboring insulating, and the normal metallic state above Tc and the challenge for all unconventional superconductors.
The molecular A3C60 fulleride superconductors have a parent antiferromagnetic insulator in common with the atom-based cuprates, but here, the C603– electronic structure controls the geometry and spin state of the structural building unit via the on-molecule Jahn-Teller effect, they said.
“We identify the Jahn-Teller metal as a fluctuating microscopically heterogeneous coexistence of both localized Jahn-Teller–active and itinerant electrons that connects the insulating and superconducting states of fullerides,” they explained in their abstract published in Science Advances.
“The balance between these molecular and extended lattice features of the electrons at the Fermi level gives a dome-shaped variation of Tc with interfulleride separation, demonstrating molecular electronic structure control of superconductivity,” they explained.
Prassides earlier worked with the Department of Chemistry, Durham University, UK and shifted to the Advanced Institute of Materials Research (AIMR), Tohoku University, Japan last year, where the research on new materials was going on for two decades.
His new laboratory on Functional Molecular Materials at the AIMR has been doing research on a range of structural, dynamic, magnetic, and electronic problems in contemporary materials science.
“We use core chemical approaches to access unusual structures and electronic, conducting, and magnetic ground states and probe the physics in key proof-of-concept materials, including mixed valency systems, porous framework materials, low-dimensional magnetic solids and photo-switchable molecular magnets, intermetallic Kondo insulators, superconducting oxides, borides, and pnictides, carbon nanotubes, fullerenes and heterofullerenes, and their superconducting and ferromagnetic derivatives,” says the lab on its website.