  The kagome superconductor family AV3Sb5 (A=Cs, K, Rb) emerged as an exciting
platform to study exotic Fermi surface instabilities. Here we use
spectroscopic-imaging scanning tunneling microscopy (SI-STM) and angle-resolved
photoemission spectroscopy (ARPES) to reveal how the surprising cascade of
higher and lower-dimensional density waves in CsV3Sb5 is intimately tied to a
set of small reconstructed Fermi pockets. ARPES measurements visualize the
formation of these pockets generated by a 3D charge density wave transition.
The pockets are connected by dispersive q* wave vectors observed in Fourier
transforms of STM differential conductance maps. As the additional 1D charge
order emerges at a lower temperature, q* wave vectors become substantially
renormalized, signaling further reconstruction of the Fermi pockets.
Remarkably, in the superconducting state, the superconducting gap modulations
give rise to an in-plane Cooper pair-density-wave at the same q* wave vectors.
Our work demonstrates the intrinsic origin of the charge-stripes and the
pair-density-wave in CsV3Sb5 and their relationship to the Fermi pockets. These
experiments uncover a unique scenario of how Fermi pockets generated by a
parent charge density wave state can provide a favorable platform for the
emergence of additional density waves.
