Strain Relaxation in Atomic Flat SrRu $_{1-{\rm x}}$ O $_{3}$ /SrTiO <

Strain-relaxed atomically flat SrRu_1-xO₃ layers can be grown on SrTiO₃ substrate by a standard off-axis RF sputtering technique without using buffer layers. High RF power generated a high concentration of Ru vacancies proportional to the enlarged unit cell volume. The strong interface strain is relaxed by nano-crystal-defects induced by the large Ru vacancies and thin amorphous layer sitting in between film-substrate interface. Because of the structural defects and large unit cell expansion, the T_C is lowered to 110-137 K as compared to bulk value of 161 K. Strong uniaxial anisotropy along [001] direction indicates that the intrinsic bulk SrRuO₃ anisotropy dominating over the lattice expansion induced cubic anisotropy.