  Here, we study diffusive spin transport in two dimensions and demonstrate
that an intrinsic analog to a previously predicted extrinsic spin swapping
effect, where the spin polarization and the direction of flow are interchanged
due to spin-orbit coupling at extrinsic impurities, can be induced by intrinsic
(Rashba) spin-orbit coupling. The resulting accumulation of intrinsically
spin-swapped polarizations is shown to be much larger than for the extrinsic
effect. Intrinsic spin swapping is particularly strong when the system
dimensions exceed the spin-orbit precession length and the generated transverse
spin currents are of the order of the injected primary spin currents. In
contrast, spin accumulations and spin currents caused by extrinsic spin
swapping are proportional to the spin-orbit coupling. We present numerical and
analytical results for the secondary spin currents and accumulations generated
by intrinsic spin swapping, and we derive analytic expressions for the induced
spin accumulation at the edges of a narrow strip, where a long-range
propagation of spin polarizations takes place.
