Organic radicals have long been suggested as candidates
for organic
magnets and components in organic spintronic devices. Herein, we demonstrate
spin current emission from an organic radical film via spin pumping
at room temperature. We present the synthesis and the thin film preparation
of a Blatter-type radical with outstanding stability and low roughness.
These features enable the fabrication of a radical/ferromagnet bilayer,
in which the spin current emission from the organic radical layer
can be reversibly reduced when the ferromagnetic film is brought into
simultaneous resonance with the radical. The results provide an experimental
demonstration of a metal-free organic radical layer operating as a
spin source, opening a new avenue for the development of purely organic
spintronic devices and bridging the gap between potential and real
applications.