Field Dynamic Effects in Perpendicular Exchange-Biased [Pt/Co]/IrMn Multilayers

The field sweep rate dependence of the exchange bias field in (2 nm Pt/0.5 nm Co)3/t Pt/10 nm IrMn multilayers with t ranging from 0 to 1.2 nm were studied. The samples were grown by DC magnetron sputtering onto SiO₂ substrates at room temperature. In this configuration, the exchange bias is established without a field annealing treatment since the IrMn layer is deposited on top of a magnetically saturated Co/Pt multilayer. The dynamic measurements were conducted with a magneto-optical Kerr effect set-up at room temperature and images of the magnetization reversal process were recorded by Kerr microscopy. The applied magnetic field was varied linearly in order to keep the field sweep rate constant during the entire magnetization loop.