Domain-size-dependent exchange bias in Co∕LaFeO3

X-ray microscopy using magnetic linear dichroism of a zero-field-grown multidomain Co∕LaFeO3 ferromagnet∕antiferromagnet sample shows a local exchange bias of random direction and magnitude. A statistical analysis of the local bias of individual micron-size magnetic domains demonstrates an increasing bias field with decreasing domain size as expected for a random distribution of pinned, uncompensated spins, which are believed to mediate the interface coupling. A linear dependence with the inverse domain diameter is found.