Thin films of TbMnO3 have been grown on SrTiO3 substrates. The films grow under compressive strain and are only partially clamped to the substrate. This produces remarkable changes in the magnetic properties and, unlike the bulk material, the films d
isplay ferromagnetic interactions below the ordering temperature of ~40K. X-ray photoemission measurements in the films show that the Mn-3s splitting is 0.3eV larger than that of the bulk. Ab initio embedded cluster calculations yield Mn-3s splittings that are in agreement with the experiment and reveal that the larger observed values are due to a larger ionicity of the films.
Metastable manganite perovskites displaying the antiferromagnetic so-called E-phase are predicted to be multiferroic. Due to the need of high-pressures for the synthesis of this phase, this prediction has only been confirmed in bulk HoMnO3. Here we r
eport on the growth and characterization of YbMnO3 perovskite thin films grown under epitaxial strain. Highly-oriented thin films, with thickness down to ~30nm, can be obtained showing magneto-dielectric coupling and magnetic responses as those expected for the E-phase. We observe that the magnetic properties depart from the bulk behavior only in the case of ultrathin films (d< 30nm), which display a glassy magnetic behavior. We show that strain effects alone cannot account for this difference and that the film morphology plays, instead, a crucial role.
