Irradiation-induced enhancement of Fe and Al magnetic polarizations in Fe60Al40 films

Abstract

The rise of Fe magnetic moment, changes in Al electronic structure and a variation of Al magnetic polarization in thin films of transition metal aluminide Fe _60 Al _40 have been probed through the order-disorder phase transition by soft x-ray absorption spectroscopy and x-ray resonant magnetic reflectivity in the extreme ultraviolet regime. In a course of the transition induced by 20 keV Ne ^+ irradiation with low fluences (∼10 ^14 ions cm ^−2 ), x-ray magnetic circular dichroism spectra taken at the Fe L $_{2,3}$ absorption edges at room and low temperatures revealed a pronounced increase of Fe $3\textit{d}$ states spin-polarization. X-ray resonant magnetic reflectivity applied to the Al L $_{2,3}$ and Fe M $_{2,3}$ edges allowed to detect the magnetic polarization of Al atoms in the films. The changes in Al electronic structure have been seen by alteration of Al K edge x-ray absorption near edge structure. A difference in anisotropy fields for films before and after irradiation has been observed by element-specific hysteresis loops recorded at low temperatures in absorption and reflection geometries at the Fe L $_{2,3}$ and M $_{2,3}$ edges, respectively. An attempt to reduce the top oxide layer by an inductively coupled hydrogen plasma has shown a possibility to recover the chemically ordered phase.

Keywords

• chemical disorder
• ion-irradiation
• XANES
• XMCD
• plasma treatment