Breaking of Coulomb blockade by macrospin-assisted tunneling

A magnet with precessing magnetization pumps a spin current into adjacent leads. As special case of this pumping, macrospin (magnetization) can assist electrons in tunneling. In small systems, however, the Coulomb blockade effect block transport electrons. Here, we investigate competition between macrospin-assisted tunneling and for simplest system where both effects meet; namely, single tunnel junction normal metal metallic ferromagnet magnetization. By combining Fermi's golden rule dynamics charging effects, show that soften or even break blockade. The details these effects---softening breaking blockade---depend on dynamics. This allows us, example, to measure via system's current-voltage characteristics. It also us control electrically. From general perspective, our results provide platform interplay spintronics electronics mesoscopic scale. We expect work basis study more complicated spintronic systems.