Two-Dimensional Photogalvanic Spin-Battery

Pure spin current is of central importance in spintronics. Here, we propose a two-dimensional (2D) spin-battery system that delivers pure spin current without an accompanying charge current to the outside world at zero bias. The principle of the spin battery is rooted in the photogalvanic effect (PGE) and the system has good operational stability against structural perturbation, photon energy, and other material characteristics. The principle of the device is numerically implemented in the 2D material phosphorene as an example, and first-principles calculations give excellent qualitative agreement with the physics of the PGE. The 2D spin battery is interesting as it is both a device that generates pure spin currents and also an energy source that harvests photons. Given the versatile operational space, the spin battery should be experimentally feasible.