  MnBi2Te4 (MBT) is the first intrinsic magnetic topological insulator with the
interaction of spin-momentum locked surface electrons and intrinsic magnetism,
and it exhibits novel magnetic and topological phenomena. Recent studies
suggested that the interaction of electrons and magnetism can be affected by
the Mn-doped Bi2Te3 phase at the surface due to inevitable structural defects.
Here we report an observation of nonreciprocal transport, i.e.
current-direction-dependent resistance, in a bilayer composed of
antiferromagnetic MBT and nonmagnetic Pt. The emergence of the nonreciprocal
response below the N\'eel temperature confirms a correlation between
nonreciprocity and intrinsic magnetism in the surface state of MBT. The angular
dependence of the nonreciprocal transport indicates that nonreciprocal response
originates from the asymmetry scattering of electrons at the surface of MBT
mediated by magnon. Our work provides an insight into nonreciprocity arising
from the correlation between magnetism and Dirac surface electrons in intrinsic
magnetic topological insulators.
