  Recent advances in the brilliance of hard-X-ray beamlines and photoelectron
momentum microscopy facilitate bulk valence-band mapping and
core-level-resolved hard-X-ray photoelectron diffraction (hXPD) for structural
analysis in the same setup. High-quality MBE-grown (In,Ga,Mn)As films represent
an ideal testing ground, because of the non-centrosymmetric GaAs crystal
structure itself and In and Mn doping concentrations of few percent. Here we
present results of k-mapping and hXPD for the title compound with 3% In and 2.5
or 5.6% Mn using hard X-ray photons (3 to 5 keV) at beamline P22 at PETRA III
(DESY, Hamburg). Numerical processing (difference or ratio images) emphasizes
subtle differences of hXPD patterns like the fingerprint-like hXPD-signatures
of As and Ga sites. XPD calculations using the Bloch-wave method show a
one-to-one correspondence with the measurements. The hXPD results reveal a
predominant Ga substitutional site for Mn. Valence band mapping shows that the
Fermi energy lies within the valence band and decreases as the Mn concentration
increases. The results support the p-d Zener model of ferromagnetism in the
title compound. In addition to the shift of the Fermi energy, the band
splitting increases with increasing Mn content, which we attribute to an
increase of many-body correlations with increasing metallicity of the sample.
