Supplementary Information: Mechanism of magnetization reduction in iron oxide nanoparticles

a Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science JCNS at Heinz Maier-Leibnitz Zentrum MLZ, 85748 Garching, Germany. b Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science JCNS-2 and Peter Grünberg Institute PGI-4, JARA-FIT, 52425 Jülich, Germany. c Lehrstuhl für Experimentalphysik IV C, RWTH Aachen University, 52056 Aachen, Germany. d Forschungszentrum Jülich GmbH, Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institue, 52425 Jülich, Germany. e Jülich Centre for Neutron Science (JCNS-1) and Institute for Complex Systems (ICS-1), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany f Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg, Germany. g Paul Scherrer Institut, Swiss Light Source, 5232 Villigen PSI, Switzerland.