High-pressure phase diagrams of FeSe<sub>1-x</sub>Te<sub>x</sub>: correlation between suppressed nematicity and enhanced superconductivity.
basic_science · Level V
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- Record sourced from PubMed, PMID 33452257.
- Also identified by DOI 10.1038/s41467-020-20621-2 and PMC identifier 7810696.
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Abstract
The interplay among magnetism, electronic nematicity, and superconductivity is the key issue in strongly correlated materials including iron-based, cuprate, and heavy-fermion superconductors. Magnetic fluctuations have been widely discussed as a pairing mechanism of unconventional superconductivity, but recent theory predicts that quantum fluctuations of nematic order may also promote high-temperature superconductivity. This has been studied in FeSe<sub>1-x</sub>S<sub>x</sub> superconductors exhibiting nonmagnetic nematic and pressure-induced antiferromagnetic orders, but its abrupt suppression of superconductivity at the nematic end point leaves the nematic-fluctuation driven superconductivity unconfirmed. Here we report on systematic studies of high-pressure phase diagrams up to 8 GPa in high-quality single crystals of FeSe<sub>1-x</sub>Te<sub>x</sub>. When Te composition x(Te) becomes larger than 0.1, the high-pressure magnetic order disappears, whereas the pressure-induced superconducting dome near the nematic end point is continuously found up to x(Te) ≈ 0.5. In contrast to FeSe<sub>1-x</sub>S<sub>x</sub>, enhanced superconductivity in FeSe<sub>1-x</sub>Te<sub>x</sub> does not correlate with magnetism but with the suppression of nematicity, highlighting the paramount role of nonmagnetic nematic fluctuations for high-temperature superconductivity in this system.