  Non-local spin injection in lateral spin valves generates a pure spin current
which is a diffusive flow of spins (i.e. spin angular momentums) with no net
charge flow. The diffusive spins lose phase coherency in precession while
undergoing frequent collisions and these events lead to a broad distribution of
the dwell time in a transport channel between the injector and the detector.
Here we show the lateral spin-valves with dual injectors enable us to detect a
genuine in-plane precession signal from the Hanle effect, demonstrating the
phase coherency in the in-plane precession is improved with an increase of the
channel length. The coherency in the spin precession shows a universal behavior
as a function of the normalized separation between the injector and the
detector in material-independent fashion for metals and semiconductors
including graphene.
