We report the first search for the elastic scatterings between cosmic-ray
boosted sub-MeV dark matter and electrons in the PandaX-4T liquid xenon
experiment. Sub-MeV dark matter particles can be accelerated by scattering with
electrons in the cosmic rays and produce detectable electron recoil signals in
the detector. Using the commissioning data from PandaX-4T of
0.63 tonne·year exposure, we set new constraints on DM-electron
scattering cross sections for DM masses ranging from 10 eV/c^2 to
3 keV/c^2.
