  Nonreciprocal charge transport, which is frequently termed as electrical
magnetochiral anisotropy (EMCA) in chiral conductors, touches the most
important elements of modern condensed matter physics. Here, we have
investigated the EMCA in Pt/PtMnGa (PMG) bilayers with the assitance of
nonequilibrium fluctuation theorems. Large EMCA in the Pt/PMG bilayers can be
attributed to nonreciprocal response of an interface-driven chiral transport
channel. Due to the presence of large charge fluctuations for small current
region, higher order EMCA coefficients should be added and they are all
functions of current. A combination of asymmetrical electron scattering and
spin-dependent scattering furnish the PMG thickness dependent chiral transport
behaviors in Pt/PMG bilayers. The dramatically enhanced anomalous Hall angle of
PMG further demonstrates the modified surface state properties by strong
spin-orbit coupling.
