  Exchange bias has been studied in a series of La2/3Ca1/3MnO3 / La1/3Ca2/3MnO3
bilayers grown on (001) SrTiO3 substrates by ozone-assisted molecular beam
epitaxy. The high crystalline quality of the samples and interfaces has been
verified using high-resolution X-ray diffractometry and Z-contrast scanning
transmission electron microscopy with electron energy loss spectroscopy. The
dependence of exchange bias on the thickness of the antiferromagnetic layer has
been investigated. A critical value for the onset of the hysteresis loop shift
has been determined. An antiferromagnetic anisotropy constant has been obtained
by fitting the results to the generalized Meiklejohn-Bean model.
