The exchange bias effect is investigated in CoFeB / MnIr multilayers system with perpendicular magnetic anisotropy. An interlayer of Pt (0.5nm) between CoFeB and MnIr layer enhanced both the perpendicular anisotropy and the exchange bias. Both the exchange bias and the coercivity field depend on the thickness of the MnIr layer, the largest exchange bias field of 201.7 Oe was obtained in a 5nm MnIr thickness samples which had been annealed at 573 K in external magnetic fi eld. The exchange bias becomes weaker when the thickness of the Cu or Pd underlayer increases in [Pd / CoFeB] 4 / MnIr multilayer system. The Gilbert damping constant obtained from the Kerr effect (TR-MOKE) measurement increases as the thickness of Cu or Pd underlayer increases. However, in the pump-probe measurement, the exchange bias fi elds decreased before the Kerr signal starts change and restored when the change of the Kerr signal reaches its maxima, the total time of this process is about 1 ps. The loss of the exchange bias is probably attributed to the electron temperature. The relation between the exchange bias and the Gilbert damping constant is detail discussed.
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