Xie Jianyu, Liu Xinyou, Zhang Wei, Wong Sum Ming, Zhou Xuefeng, Zhao Yusheng, Wang Shanmin, Lai Kwing To, Goh Swee K
Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China.
Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
Nano Lett. 2021 Nov 10;21(21):9310-9317. doi: 10.1021/acs.nanolett.1c03508. Epub 2021 Oct 29.
The emergence of high transition temperature () superconductivity in bulk FeSe under pressure is associated with the tuning of nematicity and magnetism. However, sorting out the relative contributions from magnetic and nematic fluctuations to the enhancement of remains challenging. Here, we design and conduct a series of high-pressure experiments on FeSe thin flakes. We find that as the thickness decreases the nematic phase boundary on temperature-pressure phase diagrams remains robust while the magnetic order is significantly weakened. A local maximum of is observed outside the nematic phase region, not far from the extrapolated nematic end point in all samples. However, the maximum value is reduced associated with the weakening of magnetism. No high- phase is observed in the thinnest sample. Our results strongly suggest that nematic fluctuations alone can only have a limited effect while magnetic fluctuations are pivotal on the enhancement of in FeSe.
在压力作用下块状FeSe中出现的高转变温度（）超导现象与向列性和磁性的调控有关。然而，厘清磁涨落和向列涨落对增强的相对贡献仍然具有挑战性。在此，我们设计并对FeSe薄片进行了一系列高压实验。我们发现，随着厚度减小，温度-压力相图上的向列相边界保持稳定，而磁有序则显著减弱。在向列相区域之外，离所有样品中外推的向列终点不远的地方，观察到的一个局部最大值。然而，最大值随着磁性的减弱而降低。在最薄的样品中未观察到高相。我们的结果有力地表明，仅向列涨落只能产生有限的影响，而磁涨落在FeSe增强中起关键作用。
