The extraordinary properties of superconductivity have regularly frustrated researchers, who have successfully identified it in many different materials, but always at temperatures too low for a widespread technological impact. The search for superconducting materials — which lack any resistance to electrical flow — has regularly frustrated researchers; while many such materials have been discovered, they only work at temperatures too low for widespread application.

A copper-oxide superconducting pellet levitates over a magnetic track. Photo credit: UBC Physics – Quantum Materials Laboratory

Those days of frustration may be coming to an end after a recent publication in Science by members of an international consortium that went looking for the underlying mechanism responsible for high-temperature superconductivity. What they found was evidence of a generic state — spatial modulations of the electronic density inside a crystal — that characterized a material’s normal state and is a precursor to the emergence of superconductivity.

This work was led by investigators with the University of British Columbia’s Quantum Matter Institute and the Max Planck-UBC Centre for Quantum Materials. After selecting copper-oxide ceramics as their model high-temperature superconductor, they performed advanced X-ray experiments at the Canadian Light Source and German BESSY synchrotrons, as well as angle-resolved photoemission at UBC and scanning tunnelling microscopy at Harvard. 

Andrea Damascelli, a physicist in the UBC Department of Physics & Astronomy who led the research effort with PhD student Riccardo Comin, says these methods revealed static ripples in the normal state of these materials, a pattern reflecting a spontaneously ordered state in proximity to superconductivity. This universal ordering of charges points the way to a common feature of all high-temperature superconducting materials, which could characterize the foundation of this physical behaviour.

Damascelli, for his part, emphasizes that the result displays the remarkable capability of powerful analytical tools such as the CLS synchrotron, which he finds to be just as impressive as this new insight into superconductivity. “These are fundamental, but very subtle, features which leave only a faint spectroscopic fingerprint,” Damascelli said in a UBC media release. “The success in detecting these tiny ripples in the electron distribution demonstrates the far-reaching power of these complementary techniques, and their pivotal, emerging role in advancing our understanding of quantum materials.”