The ability to micromachine Permalloy (Ni-Fe alloys) has become important for the development of magnetically actuated microelectromechanical systems devices and for the development of computer disk read-write heads. In this work, focused ion-beam micromachining (FIBM) of Permalloy using Ga+ and with I and Cl chemical enhancement (CE) has been investigated. Micromachining of Permalloy with Ga+ resulted in a material removal rate of only 0.10 mu m/nC and the topography of the micromachined cuts increased in roughness with increased depth reaching micrometer dimensions for the deeper cuts. In comparison to Ga+ only FIBM, I-2 CE-FIBM increased the material removal rate by a factor of 8-30 (0.83-3.0 mu m(3)/nC) for bulk and edge micromachining, respectively, with much reduced micromachining induced topography. Procedures were developed to prevent the formation of I-2 CE-FIBM related postmicromachining reaction products. Chlorine CE-FIBM, using C2Cl4, CCl4 and C2HCl5, as noncorrosive chlorine sources, provided a Permalloy material removal rate enhancement versus Ga+-only FIBM of approximately a factor of 2 and approximate to 100 Angstrom topography.