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Abstract:
This work reports on the electronic properties of thin films of the
Heusler compound Co2MnSi studied by means of hard x-ray photoelectron
spectroscopy (HAXPES). The results of photoelectron spectroscopy from
multilayered thin films excited by photons of 2-8 keV are presented. The
measurements were performed on (substrate/buffer
layer/Co2MnSi(z)/capping layer) multilayers with a thickness z ranging
from 0 to 50 nm. It is shown that high energy spectroscopy is a valuable
tool for non-destructive depth profiling. The experimentally determined
values of the inelastic electron mean free path in Co2MnSi increase from
about 19.5 to 67 angstrom on increasing the kinetic energy from about
1.9 to 6.8 keV. The influence of the thermal treatment of Co2MnSi thin
films on the electronic properties was also explored. The structure of
the thin films is significantly improved by heat treatment as revealed
by x-ray diffraction. It was found that the electronic structure of
annealed samples as measured by photoelectron spectroscopy is similar to
that of a well-ordered bulk reference sample. The samples without heat
treatment show strong deviations from the electronic structure of bulk
material. The differences between the disordered and the ordered films
are also observed in core level spectra. Chemical shifts of about 100
meV are observed at the Mn 2p states. The stronger localization of the
Mn d states in the ordered samples is obvious from the multiplet
satellite of the Mn 2p(3/2) state.
