Growth, structure, surface topography and magnetic properties of GdMnO₃ multiferroic epitaxial thin films

¹ National Science and Technology University “MISiS”, Leninskii prosp., 4, Moscow, 119049, Russia
² Laboratory of Solid State Physics and Magnetism, KU Leuven, Celestijnenlaan 200 D, BE-3001, Leuven, Belgium

Abstract

Epitaxial GdMnO₃ thin films were grown in various regimes on (001) NdGaO₃ and (001) SrTiO₃ substrates by RF magnetron sputtering. X-ray analysis revealed that the films grown at a substrate temperature of 650-900 °C are single phase (GdMnO₃ with orthorhombic Pbnm structure). Films grown on NdGaO₃ substrates at lower temperature (<750 °C) have only one out-of-plane orientation, i.e. GdMnO₃(001)||NdGaO₃(001), whereas films grown at higher temperatures (>750 °C) reveal two orientations, i.e. GdMnO₃(001)||NdGaO₃(001) and GdMnO₃(110)||NdGaO₃(001). These results are confirmed by transmission electron microscopy. Films grown on SrTiO₃ substrates have two orientations, i.e. GdMnO₃(001)||SrTiO₃(001) and GdMnO₃(110)||SrTiO₃(001), in the whole temperature range in which the phase exists. Using atomic force microscopy the correlation between the topography of the films and their crystallographic structure was studied. The magnetic properties of the films differ from those of bulk samples and revealed spin-glass behavior.