Clocked Single-Spin Source Based On A Spin-Split Superconductor

In recent years single-electron turnstiles based on superconducting/normal-metal hybrid nanostructures have been well developed, which allow the manipulation of single electrons at high frequencies. In contrast, the implementation of single-spin sources in solid-state devices is only weakly explored. In our work (\emph{N.~Dittmann, J.~Splettstoesser, F.~Giazotto, \textbf{New J.~Phys.} 18, 083019 (2016)}) we propose a new accurate clocked single-spin source for ac-spintronic applications. The device consists of a superconducting island covered by a ferromagnetic insulator (FI) layer through which it is coupled to superconducting contacts. Single-particle transfer relies on the energy gaps and the island's charging energy, and is enabled by a bias and a time-periodic gate voltage. Accurate spin transfer is achieved by the FI layer which polarizes the island, provides spin-selective tunneling barriers and improves the precision by suppressing Andreev reflection. We analyze realistic material combinations and experimental requirements which allow for a clocked spin current in the MHz regime.