Anomalous strain effect in heteroepitaxial SrRuO₃ films on（111） SrTiO₃ substrates

【摘要】 We report comprehensive investigations into the structure of high-quality（111）-oriented SrRuO₃ films on SrTiO₃ substrates to elucidate the effect of（111） heteroepitaxial strain. We found that SrRuO₃ film with a thickness of ～ 40 nm is compressively strained in plane on the substrate with full coherency. Nevertheless, the out-of-plane spacing is almost the same as in the bulk, which is at odds with the conventional paradigm. By probing a series of half-order Bragg reflections using synchrotron-based x-ray diffraction combined with analyses of the scanning transmission electron microscopy images,we discovered that the heteroepitaxial strain is accommodated via significant suppression of the degree of c+octahedral tilting and the formation of three equivalent domain structures on the（111） SrTiO₃ substrate. This anomalous effect sheds light on the understanding of an unconventional paradigm of film–substrate coupling for the（111） heteroepitaxial strain.更多还原

【Abstract】 We report comprehensive investigations into the structure of high-quality（111）-oriented SrRuO₃ films on SrTiO₃ substrates to elucidate the effect of（111） heteroepitaxial strain. We found that SrRuO₃ film with a thickness of ～ 40 nm is compressively strained in plane on the substrate with full coherency. Nevertheless, the out-of-plane spacing is almost the same as in the bulk, which is at odds with the conventional paradigm. By probing a series of half-order Bragg reflections using synchrotron-based x-ray diffraction combined with analyses of the scanning transmission electron microscopy images,we discovered that the heteroepitaxial strain is accommodated via significant suppression of the degree of c+octahedral tilting and the formation of three equivalent domain structures on the（111） SrTiO₃ substrate. This anomalous effect sheds light on the understanding of an unconventional paradigm of film–substrate coupling for the（111） heteroepitaxial strain.更多还原