  In addition to the topologically protected linear dispersion, a
band-bending-confined two-dimensional electron gas with tunable Rashba
spin-splitting (RSS) was found to coexist with the topological surface states
on the surface of topological insulators (TIs). Here, we report the observation
of large bilinear magnetoresistance (BMR) in Bi2Se3 films decorated with
transition metal atoms. The magnitude of the BMR sensitively depends on the
type and amount of atoms deposited, with a maximum achieved value close to
those of strong Rashba semiconductors. Our first-principles calculations
reproduce the quantum well states and reveal sizable RSS in all Bi2Se3
heterostructures with broken inversion symmetry. Our results show that
charge-spin interconversion through RSS states in TIs can be fine-tuned through
surface atom deposition and easily detected via BMR for potential spintronic
applications.
