Increased magnetic damping of permalloy upon Cr implantation

The static and dynamic magnetic properties of 20 nm thick permalloy films are studied as prepared and after Cr implantation with different Cr fluences. Doping results a decrease in the Curie temperature of the permalloy film with the implantation fluence. The magnetization damping is investigated by performing pulsed inductive microwave magnetometry (PIMM) for various applied magnetic fields. It is found that upon Cr implantation the PIMM amplitude decreases consistent with a decrease in the uniaxial anisotropy and a reduction in saturation magnetization. In contrast to this, a 7-fold increase of the magnetic damping is obtained for only 4% of the Cr doping.