Absence of $4a_0$ superlattice in bulk kagome superconductor CsV$_3$Sb$_5$
Haoxiang Li, Yu-Xiao Jiang, J. X. Yin, Sangmoon Yoon, Andrew R. Lupini, C. Nelson, A. Said, Y. M. Yang, H. C. Lei, Binghai Yan, Ziqiang Wang, M. Z. Hasan, H. N. Lee, H. Miao
The kagome superconductor AV$_3$Sb$_5$ (A=K, Rb, Cs) is a rare platform to
explore the interplay between topology, geometrical frustration and
symmetry-breaking orders. In addition to the charge density wave below
$T_{CDW}\sim94$~K and superconductivity below $T_{SC}\sim3$~K, recent surface
sensitive studies of CsV$_3$Sb$_5$ find evidence of 1$\times$4 superlattices
below $T^{*}\sim60$~K. Interestingly, this unidirectional $4a_0$ phase may
intertwine with charge density wave and superconductivity and possibly
responsible for spectroscopic and transport anomalies below $T^{*}$. Here,
combining high-resolution X-ray diffraction and scanning tunneling microscopy,
we demonstrate that the 1$\times$4 superstructure emerges uniquely on the
surface and hence exclude the $4a_0$ phase as the origin of $T^{*}$ anomaly in
the bulk CsV$_3$Sb$_5$.