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Zusammenfassung:
Photoelectron spectroscopy (PES) has evolved into the most relevant,
powerful, and nondestructive method for investigating atoms, molecules,
and solids. In particular, hard X-ray photoelectron spectroscopy
(HAXPES) has emerged as a powerful tool for investigating the bulk
electronic structure of materials in a variety of applied fields such as
chemistry, physics, and materials science. In addition, PES was used for
investigating the symmetries of various materials' electronic
structures. However, thus far, such studies have been restricted to
atoms, molecules, adsorbates, and surfaces because low-energy (<1 keV)
electrons have limited probing depths. This is disadvantageous because
three-dimensional (3D) bulk states cannot be studied. The present work
demonstrates that this drawback can be eliminated by using hard X-rays
with variable polarization for excitation. In the current study, this
issue was investigated using several Heusler compounds, which have been
attracting increasing levels of interest. There are more than 2000
Heusler compounds in total. Owing to their tunable electronic
structures, Heusler compounds exhibit multifarious properties useful for
spintronic, optoelectronic, shape Memory, and thermoelectric
applications. Herein, we report the results of bulk-sensitive, high
energy photoelectron spectroscopy of the valence bands of several
Heusler compounds for various applications. It is shown that the
measured valence band spectra are clearly resolved and are in good
agreement with the first-principles calculations of the compounds'
electronic structures. (C) 2013 Elsevier B.V. All rights reserved,