  Recent theory and experiments have showcased how to harness quantum mechanics
to assemble heat/information engines with efficiencies that surpass the
classical Carnot limit. So far, this has required atomic engines that are
driven by cumbersome external electromagnetic sources. Here, using molecular
spintronics, we propose an implementation that is both electronic and
autonomous. Our spintronic quantum engine heuristically deploys several known
quantum assets by having a chain of spin qubits formed by the paramagnetic Co
centers of phthalocyanine (Pc) molecules electronically interact with
electron-spin selecting Fe/C60 interfaces. Density functional calculations
reveal that transport fluctuations across the interface can stabilize spin
coherence on the Co paramagnetic centers, which host spin flip processes.
Across vertical molecular nanodevices, we measure enduring dc current
generation, output power above room temperature, two quantum thermodynamical
signatures of the engine's processes, and a record 89% spin polarization of
current across the Fe/C60 interface. It is crucially this electron spin
selection that forces, through demonic feedback and control, charge current to
flow against the built-in potential barrier. Further research into spintronic
quantum engines, insight into the quantum information processes within
spintronic technologies, and retooling the spintronic-based information
technology chain, could help accelerate the transition to clean energy.
