Mössbauer spectroscopical investigation of the exchange biased Fe / MnF 2 interface

Two different Fe/MnF2 samples have been prepared by e-beam evaporation on MgO(001) substrates. The Fe layer in the samples includes a 10 Å thick 57Fe probe layer either at the Fe/MnF2 interface (interface sample) or 35 Å away from the interface (center sample). The samples are characterized by X-ray diffraction, B. Sahoo (B) · W. Keune · V. Kuncser Fachbereich Physik, Universität Duisburg-Essen, 47048 Duisburg, Germany e-mail: [email protected] W. A. A. Macedo · J. Eisenmenger · I. K. Schuller Physics Department, University of California – San Diego, La Jolla, CA 92093, USA W. A. A. Macedo Laboratório de Física Aplicada, Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte MG, 30123-970, Brazil V. Kuncser National Institute of Physics of Materials, Bucharest-Magurele 76900, Romania J. Eisenmenger Abteilung Festkörperphysik, Universität Ulm, 89069 Ulm, Germany J. Nogués Institució Catalana de Recerca i Estudis Avançats (ICREA) and Departament de Física, Universitat Autónoma de Barcelona, 08193 Bellaterra, Spain I. Felner Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel K. Liu Physics Department, University of California, Davis, CA 95616, USA R. Röhlsberger HASYLAB@DESY, Hamburg, Germany 1372 B. Sahoo, W.A.A. Macedo, et al. conversion electron Mössbauer spectroscopy (CEMS) and SQUID magnetometry. 57Fe CEMS has been employed to study the depth dependent hyperfine interactions in Fe/MnF2 as a function of temperature between 18 K to 300 K. The hyperfine field Bhf has been obtained for the interfacial and off-interfacial 57Fe layers. At the interface, besides Bhf of bcc-Fe, the presence of a component with a distribution P(Bhf ) is observed. The latter is assigned to interfacial 57Fe atoms, indicating some (∼15%, equivalent to ∼1 Fe atomic layer) intermixing at the Fe/MnF2 interface and a decrease of the average by 21%. The influence of the interface disappears as the 57Fe probe layer is placed away from the interface. The temperature dependence of the average of the interface has been measured. The Fe spins, at remanence, are found to lie in the film plane.