Mukasa K, Matsuura K, Qiu M, Saito M, Sugimura Y, Ishida K, Otani M, Onishi Y, Mizukami Y, Hashimoto K, Gouchi J, Kumai R, Uwatoko Y, Shibauchi T
Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan.
Department of Applied Physics, University of Tokyo, Hongo, Tokyo, 113-8656, Japan.
Nat Commun. 2021 Jan 15;12(1):381. doi: 10.1038/s41467-020-20621-2.
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 FeSeS 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 FeSeTe. 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 FeSeS, enhanced superconductivity in FeSeTe 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.
磁性、电子向列性和超导性之间的相互作用是包括铁基、铜酸盐和重费米子超导体在内的强关联材料中的关键问题。磁涨落作为非常规超导的配对机制已被广泛讨论，但最近的理论预测，向列序的量子涨落也可能促进高温超导。这一点已在表现出非磁性向列序和压力诱导反铁磁序的FeSeS超导体中得到研究，但其在向列端点处超导性的突然抑制使得向列涨落驱动的超导性尚未得到证实。在此，我们报告了对高质量FeSeTe单晶高达8 GPa的高压相图的系统研究。当Te成分x(Te)大于0.1时，高压磁序消失，而在向列端点附近压力诱导的超导穹顶一直持续到x(Te)≈0.5。与FeSeS不同，FeSeTe中增强的超导性与磁性无关，而是与向列性的抑制有关，突出了非磁性向列涨落在该系统高温超导中的首要作用。
