Three physicists at the Université de Sherbrooke led an international team to first direct measurement of the critical magnetic field in cuprates, the most promising materials for superconductivity. This breakthrough resolves an enigma that has baffled researchers for 20 years and clears the way for major advances. The study is published in the prestigious journal Nature Communications.
When some materials are cooled to very low temperature, barely above absolute zero (-273 °C), they become superconductors, and their electrical and magnetic properties change radically. They acquire a nearly magical property: they carry electricity perfectly, without any energy loss.
The most promising superconducting materials are copper oxides, also called cuprates. They are, at present, the materials that become superconductors at the highest temperature, specifically -150 °C, which is halfway between absolute zero and ambient temperature.
So, for now, these materials must still be cooled down to extremely low temperatures before they become superconducting. "If this state could persist at ambient temperature, it would profoundly transform our technological world," maintains Louis Taillefer, holder of the Canada Research Chair in Quantum Materials and the study's senior investigator. The transmission of electricity around the world would be radically changed, for example. "This great dream will become possible when scientists understand how to increase the maximum value of the critical temperature by a factor of two or more."
The team has just identified one of the main mechanisms limiting the critical temperature of cuprates, which opens a new direction in determining how to increase it.
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