Charge order driven by multiple-Q spin fluctuations in heavily electron-doped iron selenide superconductors
Ziyuan Chen, Dong Li, Zouyouwei Lu, Yue Liu, Jiakang Zhang, Yuanji Li, Ruotong Yin, Mingzhe Li, Tong Zhang, Xiaoli Dong, Y. J. Yan, Donglai Feng
Abstract
Abstract Intertwined spin and charge orders have been widely studied in high-temperature superconductors, since their fluctuations may facilitate electron pairing; however, they are rarely identified in heavily electron-doped iron selenides. Here, using scanning tunneling microscopy, we show that when the superconductivity of (Li 0.84 Fe 0.16 OH)Fe 1- x Se is suppressed by introducing Fe-site defects, a short-ranged checkerboard charge order emerges, propagating along the Fe-Fe directions with an approximately 2a Fe period. It persists throughout the whole phase space tuned by Fe-site defect density, from a defect-pinned local pattern in optimally doped samples to an extended order in samples with lower T c or non-superconducting. Intriguingly, our simulations indicate that the charge order is likely driven by multiple-Q spin density waves originating from the spin fluctuations observed by inelastic neutron scattering. Our study proves the presence of a competing order in heavily electron-doped iron selenides, and demonstrates the potential of charge order as a tool to detect spin fluctuations.