Good news!
Another breakthrough, but how close are we to make superconductors a practical reality!
"... The discovery also lends tangible support to a long-held theory about superconductivity — that it could be based upon electronic nematicity, a phase of matter in which particles break their rotational symmetry. ...
For decades, physicists have attempted to prove the existence of superconductivity due to nematic fluctuations, with little success. ...
For decades, physicists have attempted to prove the existence of superconductivity due to nematic fluctuations, with little success. ...
Focusing their studies on the iron selenides with maximum nematic fluctuations, the researchers looked for a “superconducting gap” — a well-established proxy for the existence and strength of superconductivity. The STM images enabled the researchers to find a gap that was an exact match for superconductivity caused by electronic nematicity. ..."
From the abstract:
"Nematic phases, in which electrons in a solid spontaneously break rotational symmetry while preserving translational symmetry, exist in several families of unconventional superconductors. Superconductivity mediated by nematic fluctuations is well established theoretically, but it has yet to be unambiguously identified experimentally. One major challenge is that nematicity is often intertwined with other degrees of freedom, such as magnetism and charge order. The FeSe1−xSx family of superconductors provides an opportunity to explore this concept, as it features an isolated nematic phase that can be suppressed by sulfur substitution at a quantum critical point where the nematic fluctuations are the largest. Here we determine the momentum structure of the superconducting gap near the centre of the Brillouin zone in FeSe0.81S0.19—close to the quantum critical point—and find that it is anisotropic and nearly nodal. The gap minima occur in a direction that is rotated 45° with respect to the Fe–Fe direction, unlike the usual isotropic gaps due to spin-mediated pairing in other tetragonal Fe-based superconductors. Instead, we find that the gap structure agrees with theoretical predictions for superconductivity mediated by nematic fluctuations, indicating a change in the pairing mechanism across the phase diagram of FeSe1−xSx."
Highly anisotropic superconducting gap near the nematic quantum critical point of FeSe1−xSx (no public access)
Phase diagram of FeSe1−xSx, and the crystal and electronic structure of superconducting FeSe0.81S0.19. (Source)
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