[19a-W833-1~8] 11.1 Fundamental properties

[19a-W833-2] Superconducting properties of dense MgO/Mg₂Si/MgB₂ nanocomposites

Katsuya Ueno¹, Yukihito Nagashima², Yusuke Seto¹, Megumi Matsumoto¹, Takahiro Sakurai¹, Hitoshi Ohta¹, 〇Takashi Uchino¹ (1.Kobe Univ., 2.Nippon Sheet Glass)

Keywords:nanocomposite,superconductivity

n this work, we show that fully dense insulator(MgO)/semiconductor(Mg₂Si)/superconductor(MgB₂) nanocomposites with atomically smooth and continuous interfaces, including epitaxial-like MgO/Mg₂Si interfaces, are obtained by solid phase reaction between metallic magnesium and a borosilicate glass. The resulting nanocomposites exhibit a semiconductor-superconducting transition at 36 K owing to the MgB₂ nanograins surrounded by the MgO/Mg₂Si matrix. This transition is followed by the intergrain phase-lock transition at ~26 K due to the construction of Josephson-coupled network, eventually leading to a near-zero resistance state at 17 K. The method not only provides a simple process to fabricate dense nanocomposites with high-quality interfaces but also enables to investigate the electric and magnetic properties of embedded superconducting nanograins with good intergrain coupling.