Exchange bias and perpendicular anisotropy study of ultrathin Pt–Co–Pt–IrMn multilayers sputtered on float glass

We have prepared ultrathin Pt–Co–Pt–IrMn polycrystalline multilayers on float-glass substrates by DC magnetron sputtering. We have determined the optimal set of thickness for both Pt layers, the Co layer and the IrMn biasing layer so that these samples exhibit at the same time out-of-plane magnetic anisotropy and exchange bias. Kerr microscopy domain structure imaging evidences an increase of nucleation rate accompanied with inhomogeneous magnetic behavior in the case of exchange-biased films compared to Pt–Co–Pt trilayers. Polar hysteresis loops are measured in obliquely applied magnetic field conditions, allowing us to determine both perpendicular anisotropy effective constant KeffKeff and exchange-bias coupling JEJE, which are significantly different from the ones determined by standard switching field measurements.