Spin Current due to Spinlike Andreev Reflection

Abstract

We propose theoretically a spinlike Andreev reflection that may occur at the interface of a semimetal and a doped excitonic insulator. In contrast to the usual Andreev reflection, this process does not produce the charge current, but gives rise to a pure spin current. Further investigation reveals the existence of a spinlike Josephson phenomenon between two excitonic insulators with ferromagnetism, which results in a dissipationless spin current. We stress that the present spin current satisfies the conservation condition and is quite different from the spin Hall current induced from spin-orbital interactions.