Xenon-ion–induced phase transition in thin Co films

Abstract

We report on the observation of the ion-induced hcp → fcc phase transition in 75 nm thick polycrystalline Co films, which were irradiated with 200 keV Xe ions to fluences of 2.5 × 10 13 -8 × 10 15 ions/cm 2 at a temperature of 300 K. Analyses by means of Rutherford Backscattering Spectroscopy (RBS), X-Ray Diffraction (XRD), Magneto-Optical Kerr Effect (MOKE) and Vibrating Sample Magnetometry (VSM) provided information on the film thickness and the implanted Xe profiles, the phase structure, the ion-induced lattice expansion and the magnetic hysteresis, respectively. After film deposition and irradiations up to 4 × 10 14 ions/cm 2 , we predominantly found the hcp phase (XRD, uniaxial MOKE pattern) with an in-plane magnetization. The transition to fourfold in-plane magnetization typical of the fcc-phase occurred around a fluence of 2 × 10 15 ions/cm 2 . We interpreted these findings as due to rapid cooling of thermal spikes into the metastable Co-fcc phase.

Evolution of structural and magnetic properties of sputtered nanocrystalline Co thin films with thermal annealing

“…Several studies in the literature have examined thermal stability of the FCC phase in thin films [1,[13][14][15][16][17]. In some studies, the stabilisation of this metastable phase at room temperature has been attributed to rapid cooling from high temperatures [14,15].…”

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

“…The high energy density of tens of keV/nm deposited by each impinging heavy ion generates (local) thermal spikes and hence may induce phase transformations during the subsequent rapid cooling process of the spikes [16]. In the case of Figure 1, where M s denotes the saturation magnetization.…”

Amorphous stainless steel coatings prepared by reactive magnetron-sputtering from austenitic stainless steel targets

“…As a consequence of this, these results were not shown. Figure 18 shows the MOKE measurement of the sample sputtered at 673 K. A weak fourfold anisotropy can be observed, which is typical for fcc phases [39]. The coercive field is about 6 Oe.…”