SANS Study on Vortex Lattice in CsV₃Sb₅ and Cs(V_0.86Ta_0.14)₃Sb₅

The recent discovery of superconductivity in kagome metals AV₃Sb5 (A = K, Rb, Cs) has ignited substantial research interest. To help understand the nature of this intriguing kagome superconductivity, we conducted Small Angle Neutron Scattering (SANS) investigations on the vortex lattice (VL) in CsV₃Sb₅ and Cs(V_0.86Ta_0.14)₃Sb₅, with magnetic fields applied along the crystalline c-axis. Our SANS data revealed a distinct hexagonal shape in the VL diffraction pattern. The field dependence of the VL form factor in Cs(V_0.86Ta_0.14)₃Sb₅ can be described by the London model, and the resulting penetration depth and coherence length agree with prior magnetization measurements. In contrast to the exotic charge-4e and charge-6e superconductivity observed in CsV₃Sb₅, our SANS measurements support charge-2e condensation. Additionally, we observed no reorientation of the VL with changes in magnetic fields and temperatures.