Enhanced superconductivity in TiO epitaxial thin films

Titanium oxides have many fascinating optical and electrical properties, such as the superconductivity at 2 K in cubic titanium monoxide (TiO) polycrystalline bulk. However, the lack of TiO single crystals or epitaxial films has prevented systematic investigations on its superconductivity. Here, we report the basic superconductivity characterizations of cubic TiO films epitaxially grown on (0001)-oriented α-Al 2 O 3 substrates. The magnetic and electronic transport measurements confirmed that TiO is a type-II superconductor and the recorded high T c is about 7.4 K. The lower critical field ( H c1 ) at 1.9 K, the extrapolated upper critical field H c2 (0), and coherence length are about 18 Oe, 13.7 T, and 4.9 nm, respectively. With increasing pressure, the value of T c shifts to lower temperature while the normal state resistivity increases. Our results on the superconducting TiO films confirm the strategy to achieve higher T c in the epitaxial films, which may be helpful for finding more superconducting materials in various related systems. Condensed matter physics: enhancing superconductivity in TiO The cubic titanium monoxide undergoes a superconducting transition at 2 K in its bulk form. However, access to the superconductivity mechanism is blocked by the lack of TiO single crystals or epitaxial films. Now, Prof. Xiaoguang Li and his co-workers from University of Science and Technology of China and other institutions in China and USA report a success in growing cubic TiO thin films epitaxially on α-Al 2 O 3 single crystals oriented along the c-axis utilizing a pulsed laser deposition technique. Both magnetization and transport measurements suggest the type-II superconducting nature at a record high critical temperature of 7.4 K. Further characterization indicates that the increasing pressure weakens the superconductivity. This work opens an avenue towards the understanding and manipulation of superconducting behavior in titanium-based oxide superconductors.