(111)p microtwinning in SrRuO3 thin films on (001)p LaAlO3

SrRuO3 (SRO) thin films grown on (001)p (p = pseudocubic) oriented LaAlO3 (LAO) by pulsed laser deposition have been characterized using transmission electron microscopy. Observations along the h100ip 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 at ±(ooo)p (where 'o' indicates an index with an odd number) positions were obtained in left angle 110 right angle p zone-axis diffraction patterns. These were attributed to the existence of high-density twins on {111}p pseudocubic planes within the SrRuO3 films rather than to more conventional mechanisms for the generation of superstructure reflections. (orig.)