thin film growth by controlling the structural defects

The layered perovskite superconductor Sr₂RuO₄ (bulk T_c ~ 1.5 K) has been studied extensively with its possible topological superconductivity and chiral gap function (p_x ± ip_y) [1]. The superconducting Sr₂RuO₄ thin film has advantages not only for physical advances but also fruitful device application such as quantum computation [2]. However, superconducting Sr₂RuO₄ film growth has been limited since the superconductivity of Sr₂RuO₄ is extremely vulnerable to structural defects, especially out-of-phase boundaries (OPBs) [3].
In this presentation, we will present our Sr₂RuO₄ film growth focused on the suppression of OPBs. By optimizing substrates and growth condition, we achieved epitaxial Sr₂RuO₄ films with high crystallinity and smooth surfaces, confirmed by X-ray diffraction and atomic force microscopy and transmission electron microscopy. With reduced OPBs, Sr₂RuO₄ films exhibit superconductivity up to 0.8 K. Our work suggests a novel method to obtain superconducting Sr₂RuO₄ films enabling Josephson junction or spintronics device based on the Sr₂RuO_4.
[1] A. P. Mackenzie and Y. Maeno, Rev. Mod. Phys. 75, 657 (2003).
[2] T. Hyart et al., Phys. Rev. B 88, 035121 (2013).
[3] M. A. Zurbuchen et al., Appl. Phys. Lett. 78, 2351 (2001).
[4] M. Uchida et al., APL Materials 5, 106108 (2017).