Control of oxygen octahedral rotations and physical properties inSrRuO3films

Abstract

Control of octahedral rotations in the ABO${}_{3}$ perovskite oxides has been of great interest due to its potential in rationally discovering and designing new multifunctional phases. In this study, we show that octahedral rotations of the SrRuO${}_{3}$ films can be controlled by oxygen vacancies as well as by interfacial coupling, which further determines the physical properties. Half-integer reflections using high-resolution synchrotron x-ray diffraction were carried out to determine the octahedral rotation pattern of SrRuO${}_{3}$ films on SrTiO${}_{3}$ substrates. The transition of RuO${}_{6}$ rotation pattern accompanied by the structural change from monoclinic $P$2${}_{1}/m$ to tetragonal $F$4/mmc can be understood from the preference of oxygen vacancies in the SrO atomic plane and the coupling of octahedra across the interface between film and substrate. The field angle dependence of magnetoresistance further confirmed the structural phase transition with changes in octahedral rotations. The monoclinic phase has the uniaxial magnetic easy axis 30\ifmmode^\circ\else\textdegree\fi{} away from the [001] direction towards the [010] direction while the tetragonal phase has uniaxial magnetic easy axis along the fourfold axis which is perpendicular to the film surface. This study demonstrates the ability to control the octahedral rotations in perovskite films and its importance when designing thin films and multilayers with desired functional property.