  We demonstrate efficient intrinsic spin-to-charge current conversion in a
two-dimensional electron gas using an all-epitaxial single-crystal
heterostructure of LaSrMnO3/ LaAlO3 (LAO)/ SrTiO3 (STO), which can suppress
spin scattering and give us an ideal environment to investigate intrinsic
spin-charge conversion. With decreasing temperature to 20 K, the spin-to-charge
conversion efficiency is drastically enhanced to +3.9 nm, which is the largest
positive value ever reported for LAO/STO. Our band-structure calculation well
reproduces this behavior and predicts further enhancement by controlling the
density and relaxation time of the carriers.
