  We have performed magnetic measurements like temperature (T), cooling field
(HFC) dependence of exchange bias (EB) and training effect to investigate the
magnetic nature of the interface of the Fe/Ir20Mn80 systems. Thin film bilayer
samples of different thicknesses of Ir20Mn80 have been prepared by dc magnetron
sputtering at room temperature. The variation of exchange bias field (HEB) with
the increase in thickness of Ir20Mn80 predicts the antiferromagnet (AFM) bulk
spins contribution to EB. Exponential decay of HEB and coercive field (HC) with
temperature reveals the presence of spin glass (SG) like interface. Also, the
decrease of HEB with increasing HFC confirms the SG like frustration at the
interface. Further, the fitting of training effect experimental data envisages
the presence of frozen and rotatable spins at the magnetically frustrated
interface of these EB systems.
