  We report a systematic study on Edelstein magnetoresistance (Edelstein MR) in
Co25Fe75/Cu/Bi2O3 heterostructures with a strong spin-orbit interaction at the
Cu/Bi2O3 interface. We succeed in observing a significant dependence of the
Edelstein MR on both Cu layer thickness and temperature, and also develop a
general analytical model considering distinct bulk and interface contributions
on spin relaxation. Our analysis, based on the above model, quantitatively
illustrates a unique property of the spin transport near the Rashba interface,
revealing a prominent role of the spin relaxation process by determining the
ratios of the spin relaxation inside and outside the interface. We further find
the characteristic spin transport is unaffected by temperature. Our results
provide an essential tool for exploring the transport in a system with
spin-momentum-locked two-dimensional states.
