The magneto-optical properties of annealed Co96Pt4 nanowire arrays

Abstract

The magneto-optical (MO) properties of highly ordered arrays of electrodeposited Co96Pt4 alloy nanowires embedded in anodic aluminum oxide (AAO) membranes have been studied as a function of annealing temperature (TA). The initial measurements yielded the four Stokes parameters from which the Faraday rotation angle (FRA) and ellipticity (tanχ) were extracted. The FRA was determined as 8.0×103deg∕cm for the as-deposited sample. After annealing at 300°C the FRA attained a maximum of 1.1×104deg∕cm (an increase of 38%), but thereafter declined monotonically as TA was increased to 650°C. The ellipticity shows a similar behavior with TA. However, the corresponding variation in saturation magnetization (Ms) with TA does not match that of the magneto-optical constants, which suggests that factors other than Ms also determine the values of FRA and tanχ. The data obtained indicate that a suitable annealing regime is an effective method to optimize the MO properties of AAO-based magnetic nanowire arrays.