  We consider a heterostructure consisting of a normal metal and a
superconductor separated by a spin-active interface. At finite-bias voltages,
spin-filtering and spin-mixing effects at the interface allow for an induced
magnetization (spin imbalance) on the superconducting side of the junction,
which relaxes to zero in the bulk. Such interfaces are also known to host a
pair of in-gap Andreev bound states which were recently observed
experimentally. We show that these states are responsible for the dominant
contribution to the induced spin imbalance close to the interface. Motivated by
recent experiments on spin-charge density separation in superconducting
aluminum wires, we propose an alternative way to observe spin imbalance without
applying an external magnetic field. We also suggest that the peculiar
dependence of the spin imbalance on the applied bias voltage permits an
indirect bound-state spectroscopy.
