  Changes of the electronic structure accompanied by charge localization and a
transition to an antiferromagnetic ground state were observed in the
(DOEO)$_4$[HgBr$_4$]TCE organic semiconductor. Localization starts in the
region of about 150 K and the antiferromagnetic state occurs below 60 K. The
magnetic moment of the crystal contains contributions of antiferromagnetic
inclusions (droplets), individual paramagnetic centers formed by localized
holes and free charge carriers at 2 K. Two types of inclusions of 100-400 nm
and 2-5 nm sizes were revealed by transmission electron microscopy. Studying
the symmetry of the antiferromagnetic droplets (100-400 nm inclusions) and
individual localized holes by electron spin resonance (ESR) revealed
fingerprints of the antiferromagnetic resonance spectra of the spin correlated
droplets as well as paramagnetic resonance spectra of the individual localized
charge carriers. Photoelectron spectroscopy in the VUV, soft and hard X-ray
range shows temperature-dependent effects upon crossing the critical
temperature. The substantially different probing depths of soft and hard X-ray
photoelectron spectroscopy yield information on the surface termination. The
combined investigation using soft and hard X-ray photons to study the same
sample results in details of electronic structure including structural aspects
at the surface.
