(111)(p) microtwinning in SrRuO(3) thin films on (001)(p) LaAlO(3).

SrRuO(3) (SRO) thin films grown on (001)(p) (p = pseudocubic) oriented LaAlO(3) (LAO) by pulsed laser deposition have been characterized using transmission electron microscopy. Observations along the 100(p) directions suggests that although the SRO layer maintains a pseudocube-to-pseudocube orientation relationship with the underlying LAO substrate, it has a ferroelastic domain structure associated with a transformation on cooling to room temperature to an orthorhombic Pbnm phase (a(-)a(-)c(+) Glazer tilt system). In addition, extra diffraction spots located at +/-1/6(ooo)(p) and +/-1/3(ooo)(p) (where ;o' indicates an index with an odd number) positions were obtained in 110(p) zone-axis diffraction patterns. These were attributed to the existence of high-density twins on {111}(p) pseudocubic planes within the SrRuO(3) films rather than to more conventional mechanisms for the generation of superstructure reflections.