Atomic structure of functional interfaces in Sr3Ru2O7/Sr2RuO4 eutectic crystals

Sr2RuO4 /Sr3Ru2O7 eutectic system is investigated by transmission electron microscopy TEM and high angle annular dark field scanning TEM STEM. The Sr2RuO4 /Sr3Ru2O7 lamellar structure allows studying tunneling and proximity effects between spin-triplet superconductor Sr2RuO4 and metamagnetic normal metal Sr3Ru2O7. Our analyses reveal two typologies of interfaces within the eutectic: interfaces parallel to the growth direction are sharp and defect-free whereas interfaces perpendicular to the growth direction appear wavy and decorated with Ru precipitates. These results indicate that interfaces parallel to the growth direction are the best candidates for Sr2RuO4 /Sr3Ru2O7 natural junctions to study the unusual superconductivity of Sr2RuO4.