The growth of metastable fcc Fe₇₈Ni₂₂ thin films on H-Si(100) substrates suitable for focused ion beam direct magnetic patterning

J. Gloss, M. Horký, V. Křižáková, L. Flajšman, M. Schmid, M. Urbánek, P. Varga

Appl. Surf. Sci. 469 (2019) 747-752

We have studied the growth of metastable face-centered-cubic, non-magnetic Fe₇₈Ni₂₂ thin films on silicon substrates. These films undergo a magnetic (paramagnetic to ferromagnetic) and structural (fcc to bcc) phase transformation upon ion beam irradiation and thus can serve as a material for direct writing of magnetic nanostructures by a focused ion beam. So far, these films were prepared only on single-crystal Cu(100) substrates. We show that transformable Fe₇₈Ni₂₂ thin films can also be prepared on a hydrogen-terminated Si(100) with a 130-nm-thick Cu(100) buffer layer. The H-Si(100) substrates can be prepared by hydrofluoric acid etching or by annealing at 1200 °C followed by adsorption of atomic hydrogen. The Cu(100) buffer layer and Fe₇₈Ni₂₂ fcc metastable thin film were deposited by thermal evaporation in ultra-high vacuum. The films were consequently transformed in-situ by 4 keV Ar⁺ ion irradiation and ex-situ by a 30 keV Ga⁺ focused ion beam, and their magnetic properties were studied by magneto-optical Kerr effect magnetometry. The substitution of expensive copper single crystal substrate by standard silicon wafers dramatically expands application possibilities of metastable paramagnetic thin films for focused-ion-beam direct magnetic patterning.

Corresponding author: Michal Urbánek.

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A preprint is available at arXiv.org.