Heavy Ion Irradiated Ferromagnetic Films: The Cases of Cobalt and Iron

Abstract

Polycrystalline, e-gun deposited Co, Fe and Co/Fe films, tens of nanometers thick, have been irradiated with Ne, Kr, Xe and/or Fe ions to fluences of up to 5 Â 10 16 ions/cm 2 . Changes in the magnetic texture induced by the implanted ions have been measured by means of hyperfine methods, such as Magnetic Orientation Mössbauer Spectroscopy (Fe), and by Magneto-Optical Kerr Effect and Vibrating Sample Magnetometry. In Co and CoFe an hcp Y fcc phase transition has been observed under the influence of Xe-ion implantation. For 10 16 Xe-ions/cm 2 , ion beam mixing in the Co/Fe system produces a soft magnetic material with uniaxial anisotropy. The effects have been correlated with changes in the microstructure as determined via X-ray diffraction. The influences of internal and external strain fields, an external magnetic field and pre-magnetization have been studied. A comprehensive understanding of the various effects and underlying physical reasons for the modifications appears to emerge from these investigations.

Magnetic effects induced by self-ion irradiation of Fe films

“…However, in these studies no changes in the magnetization were reported. This is attributed either to the existence of implantation effects [13,14], which is not the case in the current work, or the use of much lower fluences (two orders of magnitude lower) [11,12] than in the current work.…”

“…In the literature, changes in the structural and magnetic properties of iron films induced by heavy ion irradiation and/or implantation are reported [11][12][13][14]. However, in these studies no changes in the magnetization were reported.…”

Development of Effective Technique for Irradiating Samples of Thin Films Using the Focused Ion Beam

“…A similar process is observed by the authors of [3] in Fe/Si films. Also, do not rule out the possibility of partial amorphization of the film and phase transitions that can be caused by ion irradiation [4][5]. Future studies by means of transmission electron microscopy and X-ray diffraction analysis will clarify the nature of changes in the structure of cobalt films under the influence of Ga+ ions.…”