Crystal structure and surface morphology of magnetron sputtering deposited hexagonal and perovskite-like YbMnO3 thin films

• Thin films YbMnO3 were grown as in hexagonal as in orthorhombic modification.
• Some single crystal substrates stabilize orthorhombic modification of YbMnO3.
• The surface of the hexagonal films revealed the spiral-shaped growth terraces.
• Structural relations between the films and the substrates has been revealed.
• The piezoresponse force microscopy demonstrated hexagonal films ferroelectric behavior.

Thin YbMnO3 films with thickness 50–100 nm were grown by RF-magnetron sputtering on NdGaO3(0 0 1), SrTiO3(0 0 1), SrTiO3(1 1 0), LaAlO3(0 0 1) and on buffer layered Pt(1 1 1)/SrTiO3(1 1 1) substrates. X-ray analysis reveals that the platinum buffer layer grown on a single crystalline SrTiO3(1 1 1) substrate as well as the hexagonal YbMnO3 film with c-axis normal to the substrate plane grow epitaxially. The orthorhombic (perovskite-like) modification of YbMnO3, which otherwise forms in a bulk hexagonal structure, has been epitaxially stabilized on NdGaO3, SrTiO3 and LaAlO3 single crystal substrates. The surface topography of the films was studied by atomic force microscopy. The surface of the hexagonal films reveals spiral-shaped growth terraces with a step height of half the c-lattice parameter. The perovskite-like films have a smooth surface with small 50–100 nm islands. Piezoresponse force microscopy was used to demonstrate the ferroelectric behavior of the hexagonal films. Thin films of a compound with a structure different from the bulk one can also show different physical properties. In the case of multiferroics it can lead to enhancing of magnetoelectric coupling.