Physicists at the University of Waterloo have found evidence that could help unravel the mystery of how superconductivity occurs.
Superconductivity, an exotic state that allows electricity to be conducted with practically zero resistance, could potentially revolutionize power distribution by allowing for super-efficient electricity grids. The same principle also allows for trains to levitate and achieve incredible speeds.
But there's a catch. In general, Superconductivity is achieved only at the extremely low temperature of 0 Kelvin (-273.15 degrees Celsius). At this temperature, electrons are paired up, allowing for electricity to be conducted with minimal resistance and almost perfect efficiency.
The goal for researchers, then, is to achieve a reliable process to make superconductivity work at room temperature. While scientists have previously achieved superconductivity at room temperature, getting it to work reliably and understanding the science behind it has proved much more difficult.
A new study by The University of Waterloo—published in Science—has revealed important details about what occurs during high-temperature superconductivity. The researchers were able to obtain evidence that indicated the presence of electron nematicity, a state in which electron clouds go into an aligned and directional order, in certain types of high-temperature superconductors.
"It has become apparent in the past few years that the electrons involved in superconductivity can form patterns, stripes or checkerboards, and exhibit different symmetries – aligning preferentially along one direction," said lead researcher David Hawthorn in the press release. "These patterns and symmetries have important consequences for superconductivity—they can compete, coexist or possibly even enhance superconductivity."
A CLOSER LOOK
By using a technique called soft x-ray scattering inside cuprates, a type of copper-oxide ceramic often used as a high-temperature superconductor, the researchers were able to observe the alignments of electrons inside.
This evidence could provide the best explanation for how and why superconductivity occurs (or fails to occur) at higher temperatures. The results of their experiment also suggest that nematicity occurs in all cuprates when temperatures dip below the critical threshold.
"In this study, we identify some unexpected alignment of the electrons – a finding that is likely generic to the high-temperature superconductors and in time may turn out be a key ingredient of the problem," said Hawthorn.
The challenge now is to understand how nematicity relates to other important properties like charge density wave fluctuations. From there, researchers can begin to determine how to take advantage of nematicity and "tune" it to result in reliable room-temperature superconductivity.