Temperature Dependence of the Hyperfine Magnetic Field at Fe Sites in Ba-Doped BiFeO<sub>3</sub> Thin Films Studied by Emission Mössbauer Spectroscopy
Juliana Heiniger-Schell,
Krish Bharuth-Ram,
Kimara Naicker,
Vusumuzi Masondo,
Thien Thanh Dang,
Marianela Escobar,
Carlos Díaz-Guerra,
Georg Marschick,
Hilary Masenda,
Haraldur P. Gunnlaugsson,
Bingcui Qi,
Iraultza Unzueta,
Sveinn Ólafsson,
Rajdeep Adhikari,
Gerrard Peters,
Deena Naidoo,
Peter Schaaf,
Dmitry Zyabkin,
Karl Johnston,
Sven Becker,
Gerhard Jakob
Affiliations
Juliana Heiniger-Schell
European Organization for Nuclear Research (CERN), CH-1211 Geneva, Switzerland
Krish Bharuth-Ram
School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4001, South Africa
Kimara Naicker
School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4001, South Africa
Vusumuzi Masondo
Physics Department, Durban University of Technology, Durban 4000, South Africa
Thien Thanh Dang
Institute for Materials Science and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 45141 Essen, Germany
Marianela Escobar
Institute for Materials Science and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 45141 Essen, Germany
Carlos Díaz-Guerra
Departmento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, Plaza de Ciencias 1, 28040 Madrid, Spain
Georg Marschick
Institute of Solid State Electronics and Center for Micro- and Nanostructures, Technische Universität Wien, 1040 Vienna, Austria
Hilary Masenda
School of Physics, University of the Witwatersrand, Wits 2050, South Africa
Haraldur P. Gunnlaugsson
Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland
Bingcui Qi
Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland
Iraultza Unzueta
Department of Applied Physics, School of Engineering Gipuzkoa, University of the Basque Country (UPV/EHU), Plaza Europa 1, 20018 San Sebastian, Spain
Sveinn Ólafsson
Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland
Rajdeep Adhikari
Quantum Materials Group, Institute for Semiconductor and Solid State Physics, Johannes Kepler University, Altenbergerstr. 69, 4040 Linz, Austria
Gerrard Peters
School of Physics, University of the Witwatersrand, Wits 2050, South Africa
Deena Naidoo
School of Physics, University of the Witwatersrand, Wits 2050, South Africa
Peter Schaaf
Chair Materials for Electrical Engineering and Electronics, Institute of Materials Science and Engineering, Institute of Micro and Nanotechnologies MacroNano®, TU Ilmenau, Gustav-Kirchhoff-Strasse 5, 98693 Ilmenau, Germany
Dmitry Zyabkin
Chair Materials for Electrical Engineering and Electronics, Institute of Materials Science and Engineering, Institute of Micro and Nanotechnologies MacroNano®, TU Ilmenau, Gustav-Kirchhoff-Strasse 5, 98693 Ilmenau, Germany
Karl Johnston
European Organization for Nuclear Research (CERN), CH-1211 Geneva, Switzerland
Sven Becker
Institute of Physics, Johannes Gutenberg University Mainz, Staudinger Weg 7, D-55099 Mainz, Germany
Gerhard Jakob
Institute of Physics, Johannes Gutenberg University Mainz, Staudinger Weg 7, D-55099 Mainz, Germany
Emission 57Fe Mössbauer spectroscopy (eMS), following the implantation of radioactive 57Mn+ ions, has been used to study the temperature dependence of the hyperfine magnetic field at Fe sites in Ba-doped BiFeO3 (BFO) thin films. 57Mn β decays (t1/2 = 90 s) to the 14.4 keV Mössbauer state of 57Fe, thus allowing online eMS measurements at a selection of sample temperatures during Mn implantation. The eMS measurements were performed on two thin film BFO samples, 88 nm and 300 nm thick, and doped to 15% with Ba ions. The samples were prepared by pulsed laser deposition on SrTiO3 substrates. X-ray diffraction analyses of the samples showed that the films grew in a tetragonal distorted structure. The Mössbauer spectra of the two films, measured at absorber temperatures in the range 301 K–700 K, comprised a central pair of paramagnetic doublets and a magnetic sextet feature in the wings. The magnetic component was resolved into (i) a component attributed to hyperfine interactions at Fe3+ ions located in octahedral sites (Bhf); and (ii) to Fe3+ ions in implantation induced lattice defects, which were characterized by a distribution of the magnetic field BDistr. The hyperfine magnetic field at the Fe probes in the octahedral site has a room temperature value of Bhf = 44.5(9) T. At higher sample temperatures, the Bhf becomes much weaker, with the Fe3+ hyperfine magnetic contribution disappearing above 700 K. Simultaneous analysis of the Ba–BFO eMS spectra shows that the variation of the hyperfine field with temperature follows the Brillouin curve for S = 5/2.
