  We investigated Co/Cu lateral spin valves by means of high-resolution
transmission soft x-ray microscopy with magnetic contrast that utilizes x-ray
magnetic circular dichroism (XMCD). No magnetic XMCD contrast was observed at
the Cu L$_3$ absorption edge, which should directly image the spin accumulation
in Cu. Although electrical transport measurements in a non-local geometry
clearly detected the spin accumulation in Cu, which remained unchanged during
illumination with circular polarized x-rays at the Co and Cu L$_3$ absorption
edges.
