Observation of an electronic order along [110] direction in FeSe.

Bu, Kunliang; Zhang, Wenhao; Fei, Ying; Zheng, Yuan; Ai, Fangzhou; Wu, Zongxiu; Wang, Qisi; Wo, Hongliang et al. · Nat Commun · 2021

basic_science · Level V

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Abstract

Multiple ordered states have been observed in unconventional superconductors. Here, we apply scanning tunneling microscopy to probe the intrinsic ordered states in FeSe, the structurally simplest iron-based superconductor. Besides the well-known nematic order along [100] direction, we observe a checkerboard charge order in the iron lattice, which we name a [110] electronic order in FeSe. The [110] electronic order is robust at 77 K, accompanied with the rather weak [100] nematic order. At 4.5 K, The [100] nematic order is enhanced, while the [110] electronic order forms domains with reduced correlation length. In addition, the collective [110] order is gaped around [-40, 40] meV at 4.5 K. The observation of this exotic electronic order may shed new light on the origin of the ordered states in FeSe.