  We study spin transport in lateral spin valves with constricted channels.
Using electromigration, we modulate the spin accumulation by continuously
varying the width of the non-magnetic channel at a single location. By fitting
the non-local spin signal data as a function of the non-magnetic channel
resistance, we extract all the relevant parameters regarding spin transport
from a single device. Simulations show that constricting the channel blocks the
diffusion of the accumulated spins rather than causing spin flipping. This
result could be used to improve the design of future spintronic devices devoted
to information processing.
