Quasiclassical boundary conditions for spin-orbit coupled interfaces with spin-charge conversion

The quasiclassical theory of superconductivity provides a methodology to study emergent phenomena in hybrid structures comprised of superconductors interfaced with other materials. A key component in this theory is the boundary condition that the Green functions describing the materials must satisfy. Recently, progress has been made toward formulating such a boundary condition for interfaces with spin-orbit coupling, the latter playing an important role for several phenomena in spintronics. Here we derive a boundary condition for spin-orbit coupled interfaces that includes gradient terms, which enables the description of spin-Hall-like effects with superconductors due to such interfaces. As an example, we show that the boundary conditions predict that a supercurrent flowing through a superconductor that is coupled to a normal metal via a spin-orbit interface can induce a nonlocal magnetization in the normal metal.