49 research outputs found
Phase Interlayer Shift and Stacking Fault in the Kagome Superconductor CsVSb
The stacking degree of freedom is a crucial factor in tuning material
properties and has been extensively investigated in layered materials. The
kagome superconductor CsVSb was recently discovered to exhibit a
three-dimensional CDW phase below TCDW ~94 K. Despite the thorough
investigation of in-plane modulation, the out-of-plane modulation has remained
ambiguous. Here, our polarization- and temperature-dependent Raman measurements
reveal the breaking of C rotational symmetry and the presence of three
distinct domains oriented at approximately 120{\deg}to each other. The
observations demonstrate that the CDW phase can be naturally explained as a 2c
staggered order phase with adjacent layers exhibiting a relative phase
shift. Further, we discover a first-order structural phase transition at
approximately 65 K and suggest that it is a stacking order-disorder phase
transition due to stacking fault, supported by the thermal hysteresis behavior
of a Cs-related phonon mode. Our findings highlight the significance of the
stacking degree of freedom in CsVSb and offer structural insights to
comprehend the entanglement between superconductivity and CDW.Comment: This manuscript was published in Phys. Rev. Let