RHEED study on continuously repeated step flow and layer-by-layer growth modes in SrRuO3/SrMnO3 superlattice

Abstract Nanolayered superlattices composed of ferromagnetic SrRuO 3 and antiferromagnetic SrMnO 3 layers were grown on SrTiO 3 (100) substrates by pulsed laser deposition. Multilayers were grown under predetermined synthesis conditions resulting in growth of SrRuO 3 and SrMnO 3 by step flow and layer-by-layer modes, respectively. The growth of SrMnO 3 was observed to occur through the layer-by-layer during the entire deposition process despite the expected increase in surface roughness because of the incorporation of SrRuO 3 upper layers. Monitoring by reflection high-energy electron diffraction (RHEED) revealed that the growth of every SrMnO 3 layer consisted of a pre-stage during which the gaps on the relatively rough SrRuO 3 surface were filled before the actual growth of the SrMnO 3 layer, which resulted in incomplete half oscillation and change from spot patterns to streaky patterns. The in-plane lattice constant did not show any considerable change in the case of SrRuO 3 and SrMnO 3 layers, despite the considerable lattice mismatch between the two materials (SrRuO 3 , SrMnO 3 ) and SrTiO 3 . On the other hand, the RHEED patterns showed the existence of lattice mismatch effects in the out-of-plane lattice constant, which showed significant strains of opposite signs in the different layers, indicating a strong dependence on the composition of the layers and superlattice periodicity. In this paper, the growth characteristics of a SrRuO 3 /SrMnO 3 multilayer along with its magnetic properties will be discussed.