Physicists map electron structure of superconductivity’s ‘doppelgänger’

Physicists have painted an in-depth portrait of charge ordering—an electron self-organization regime in high-temperature superconductors that may be intrinsically intertwined with superconductivity itself.

In two complementary studies—published in Nature Materials last week and Science in March—University of British Columbia researchers confirm that charge ordering forms a predominantly one dimensional ‘d-wave pattern’.

“Everything we can learn about the structure of charge ordering gets us a step closer to understanding how it’s intertwined with, and potentially competes with, superconductivity,” says Riccardo Comin, lead author of both papers who conducted the research while a PhD student at UBC. Comin is now a post-doctoral fellow at the University of Toronto.

Charge ordering creates instabilities in cuprate superconductors at temperatures warmer than -100 degrees Celsius. It causes some electrons to reorganize into new periodic static patterns that compete with superconductivity. The reason behind this competition has remained elusive until these studies demonstrated that charge ordering and superconductivity share the same underlying symmetry.

“Intriguingly, superconducting pairs of electrons also exhibit a so-called d-wave configuration,” says UBC physicist Andrea Damascelli, leader of the research team and senior fellow with the Canadian Institute for Advanced Research’s Quantum Materials Program. “So this gives more credence to the possibility that both phenomena are siblings feeding off an underlying common interaction.”

In March’s Science paper, Comin, Damascelli and colleagues investigated cold samples of yttrium barium copper oxide using x-rays and discovered that charge ordering produces a striped pattern, meaning the electrons self-organize along one direction rather than in two directions.

The two studies were possible thanks to the longstanding collaboration between UBC and the REIXS beamline at the Canadian Light Source, where all the x-ray experiments were performed.

“Combined,” says Comin, “our recent investigations provide a complete resolution of the symmetry of the charge order in cuprates.”

About quantum materials research at UBC

UBC has assembled a strong cluster of research scientists who study quantum structures, quantum materials, and applications for quantum devices. They are supported by strong international collaborations including a formal agreement with the Max Planck Society of Germany. Research topics include transition metal oxides, topological insulators, unconventional superconductors, oxide heterostructures, engineered optical materials and devices at the nanoscale, and many-body electronic structure of solid, surfaces, and interfaces

About high-temperature superconductors

Superconductivity—the phenomenon of electricity flowing with no resistance—occurs in some materials at very low temperatures. High-temperature cuprate superconductors are capable of conducting electricity without resistance at record temperatures, higher than the boiling point of liquid nitrogen. Because of their unrivalled characteristics, they represent the best candidates to advance current superconductor technology, which includes a broad range of applications such as: MRI, high-precision magnetometry, levitating high-speed trains, and lossless power lines.