Interplay of energy dissipation, ion-induced mixing, and crystal structure recovery, and surface effects in ion-irradiated magnetic Fe/Cr/Fe trilayers

Journal Article · Thu Dec 01 00:00:00 EST 2011 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.84.214106· OSTI ID:21596928

Brodyanski, A; Bock, W; Kopnarski, M; Reuscher, B ^[1]; Blomeier, S; Hillebrands, B ^[2]; Gnaser, H ^[2]

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1. Institut fuer Oberflaechen- und Schichtanalytik IFOS GmbH, Trippstadter Strasse 120, D-67663 Kaiserslautern (Germany)
2. Fachbereich Physik, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse 56, D-67663 Kaiserslautern (Germany)

The influence of the ion irradiation by 30 keV Ga{sup +} ions on the crystal structure, chemical ordering, magnetic properties, and topography of epitaxial Fe/Cr/Fe trilayers was investigated by different analytical techniques. We present direct experimental evidence, supported by theoretical estimates, that two processes take place concurrently due to the Ga-ion implantation. (i) A complete atom mixing of the Cr atoms within the Fe multilayers is occurring due to the collision cascades during the ballistic regime, and (ii) an essentially complete recovery of the initial single-crystal quality of the Fe multilayers by healing the melted and damaged area through the thermal spike phase occurs. Based on the experimental range distributions and theoretical modeling, channeling of Ga{sup +} ions in the experiments is found to contribute weakly to ion penetration and stopping, and the relative fraction of the well-channeled ions is marginally small. On the other hand, this weak channeling is sufficient to reduce the sputter yield by a factor of more than 5 in comparison with the sputtering of polycrystalline samples, evidence for the fact that the magnitude of channeling is not of primary importance for the sputtering. We offer an explanation for the observation of dramatic and abrupt changes in the surface roughness with increasing fluences in terms of a transformation from a single-phase single-crystal implanted region (bcc-Fe) to a mixture of the polycrystalline {alpha}-Fe-like bcc and {alpha}-Fe{sub 3}Ga structures within the outer half of the original Fe/Cr/Fe trilayer at fluences above 6.25 x 10{sup 16} ion/cm{sup 2}. The wall-like elevations appearing at the boundary of the irradiated areas were analyzed experimentally by varying the irradiation conditions. We showed that the wall size is governed by the ion-current density applied. A physical explanation for the appearance of such topographic features is presented, which would be valid for any material irradiated by a focused ion beam.

• OSTI ID: 21596928
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 84, Issue 21; Other Information: DOI: 10.1103/PhysRevB.84.214106; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BCC LATTICES
CHANNELING
CHROMIUM
CURRENT DENSITY
ENERGY LOSSES
EPITAXY
GALLIUM IONS
ION BEAMS
IRON
KEV RANGE 10-100
LAYERS
MAGNETIC PROPERTIES
MONOCRYSTALS
PHYSICAL RADIATION EFFECTS
POLYCRYSTALS
SIMULATION
SURFACES
BEAMS
CHARGED PARTICLES
CRYSTAL GROWTH METHODS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
CUBIC LATTICES
ELEMENTS
ENERGY RANGE
IONS
KEV RANGE
LOSSES
METALS
PHYSICAL PROPERTIES
RADIATION EFFECTS
TRANSITION ELEMENTS