Growth and magnetic properties of CoxNi1-x and FexNi1-x ultrathin films on Cu(100)

Abstract

We have grown ultrathin CoxNi1-x and FexNi1-x films on Cu(100) with varying stochiometry x. We find that these alloy films grow in a fee phase on Cu(100). With the surface magneto-optic Kerr effect we measured the variation of the Curie temperature T-C as a function of the film thickness n in monolayers. Fitting an empirical scaling curve to our results we are able to extrapolate the value T-C(n=x) for samples with different stochiometry. We use this framework in order to determine T-C(n=x) for FexNi1-x alloy films, in particular for concentrations close to 65% Fe content. Bulk Fe65Ni35 shows a collapse of magnetic long-range order and a fcc-to-bce structural transition, which is the so-called Invar effect. In ultrathin Fe65Ni35 films, we observe a ''quenching'' of the Invar effect, because growth on a Cu(100) substrate forces the film to adept the Cu lattice spacing thereby suppressing the structural relaxation.

Description
Keywords
CO-NI ALLOYS, THIN-FILMS, SURFACE SEGREGATION, LEED DETERMINATION, EPITAXIAL-GROWTH, PHASE-TRANSITION, SINGLE-CRYSTAL, IRON FILMS, FE FILMS, FCC IRON, Materials Science, Multidisciplinary, Physics, Applied, Physics, Condensed Matter, Materials Science, Physics
Citation
Schumann, F., Wu, S., Mankey, G., Willis, R. (1997): Growth and Magnetic Properties of CoₓNi₁₋ₓ and FeₓNi₁₋ₓ Ultrathin Films on Cu(100). Physical Review B, 56(5). DOI: https://doi.org/10.1103/PhysRevB.56.2668