Spatial manipulation of magnetic damping in ferromagnetic-antiferromagnetic films by ion irradiation

The spatial manipulation of the effective magnetic damping parameter in ferromagnetic-antiferromagnetic-ferromagnetic film systems is shown. By applying ultrathin antiferromagnetic layers in Ni(81)Fe(19)/IrMn/Ni(81)Fe(19) sandwich structures in combination with low fluence Ni-ion irradiation, a lateral control of the effective magnetic damping parameter is achieved. With irradiation, an interfacial intermixing and roughening is introduced, by which the interfacial coupling mechanisms and the magnetic state of the interlayer are altered. We find an exponential decay of all relevant magnetic property parameters with irradiation. Local irradiation is then applied to generate a magnetic layer with spatially distributed regions of different values of damping. The resulting overall relaxation time of the mixed property film is a direct superposition of the individual relaxation contributions. Thereby, the ratio of the phases with individual damping parameter determines the resulting overall damping.