Direct measurement of local magnetic moments at grain boundaries in iron

We have succeeded for the first time to directly measure the local magnetic moments in the vicinity of well-characterized grain boundaries in pure iron by electron energy loss spectroscopy on transmission electron microscope. The measured local magnetic moments are larger at the grain boundary than in the grain interior. This enhancement of magnetic moments depends on the grain boundary character. These findings suggest that the local magnetic moments at grain boundaries are likely to correlate with the free volume at grain boundaries.