Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 36: Magnetic Semiconductors (jointly with MA)

HL 36.11: Talk

Tuesday, March 27, 2012, 12:15–12:30, H 0112

Electronic structure study of the ferrospinel NiFe2O4 — •Martina Müller¹, Christian Caspers¹, Stephan Kramer-Sinzinger¹, Sven Döring^2,4, Michaela Gorgoi³, Carsten Westphal², and Claus M. Schneider^1,4 — ¹Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich — ²Experimentelle Physik 1 und DELTA, Technische Universität Dortmund — ³Helmholtz-Zentrum für Materialien und Energie, BESSY II, Berlin — ⁴Fakultät für Physik and Center for Nanointegration, Universität Duisburg-Essen

The ferrospinel NiFe2O4 is an insulating oxide with high magnetic ordering temperature. This rare combination makes it very attractive for application as magnetic building blocks in spintronics devices, i.e. as spin filter contacts to semiconductors or in artificial multiferroic heterostructures. We succeeded in growing NiFe2O4 (NFO) epitaxial thin films on SrTiO3 substrates. Since the electronic and magnetic properties of NFO thin films can strongly depend on substrate, film thickness and eventually differ from the bulk material, we clarified their electronic properties by means of photoemission spectroscopy in the soft and hard X-ray regime. This (HAX)PES study allows to element-specifically probe the chemical state of the Fe, Ni and O valence bands and core levels both in the bulk and surface-near regions. In particular, analyzing the Fe, Ni 2p and 3p states gives information on the depth-dependent cation stoichiometry and lattice site distribution, which we correlate with NFO/STO structural and magnetic properties.