Titanium dioxide is one of the most popular compounds among simple oxides. Except for the fully oxidized titanate, titanium oxides have partially filled d states and their exotic properties have captured attention. Here, we report on the discovery of superconductivity in Ti₄O₇ and γ-Ti₃O₅ in a thin film form. The epitaxial Ti₄O₇ and γ-Ti₃O₅ thin films were grown using pulsed-laser deposition on (LaAlO₃)_0.3-(SrAl_0.5Ta_0.5O₃)_0.7 and α-Al₂O₃ substrates, respectively. The highest superconducting transition temperatures are 3.0 K and 7.1 K for Ti₄O₇ and γ-Ti₃O₅, respectively. The mechanism behind the superconductivity is discussed on the basis of electrical measurements and previous theoretical predictions. We conclude that the superconductivity arises from unstabilized bipolaronic insulating states with the assistance of oxygen non-stoichiometry and epitaxial stabilization.

中文翻译：

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Ti4O7和γ-Ti3O5薄膜中的超导性。

二氧化钛是简单氧化物中最受欢迎的化合物之一。除完全氧化的钛酸酯外，钛氧化物具有部分填充的d态，其奇特的性能引起了人们的注意。在这里，我们对超导的以Ti发现报告₄ ö ₇和γ-Ti系₃ ø ₅在薄膜形式。外延的Ti ₄ ö ₇和γ-Ti系₃ ö ₅薄膜，使用于（LaAlO中脉冲激光沉积生长₃）_0.3 - （的SrAl _0.5的Ta _0.5 ø ₃）_0.7和的α-Al ₂ ö ₃基板。最高的超导转变温度是3.0 K和7.1 K中的Ti ₄ ö ₇和γ-Ti系₃ ø ₅，分别。在电学测量和先前的理论预测的基础上讨论了超导性背后的机理。我们得出的结论是，超导性是由不稳定的双极子绝缘态在氧非化学计量和外延稳定的帮助下产生的。