  In the topological phase of spin-orbit coupled nanowires Majorana bound
states are known to localize at the nanowire edges and to exhibit a spin
density orthogonal to both the magnetic field and the spin-orbit field. By
investigating a nanowire exposed to a uniform magnetic field with an interface
between regions with different spin-orbit couplings, we find that the
orthogonal spin density is pinned at the interface even when both interface
sides are in the topologically trivial phase, and even when no bound state is
present at all. A trivial bound state may additionally appear at the interface,
especially if the spin-orbit coupling takes opposite signs across the
interface. However, it can be destroyed by a smoothening of the spin-orbit
profile or by a magnetic field component parallel to the spin-orbit field. In
contrast, the orthogonal spin density persists in various and realistic
parameter ranges. We also show that, while the measurement of bulk equilibrium
spin currents has been elusive so far, such robust orthogonal spin density peak
may provide a way to detect spin current variations across interfaces.
