Development of new phase in ruthenium oxides using molecular beam epitaxy method*

The ruthenium oxides are known to have the layered structure and the anisotropic superconductivity. Especially, Ca₂RuO₄ shows remarkable property change applied by electrical field or pressure. We focus on Ca₂RuO₄ and its related compounds to research new phase in order to develop noble physical properties.
We prepare the samples using a molecular beam epitaxy system. The substrates are LaAlO₃, SrTiO₃, CaF₂, and YSZ. The growth temperature is 500-800 °C. We used O₂, O^*, O₃ as the oxide source. We measured the X-ray diffraction, energy dispersive X-ray spectroscopy, temperature dependence of electrical resistivity.
We have succeeded in fabrication of Ca₂RuO₄ films. The temperature dependence of electrical resistivity depends on ρ ~ exp(1/T^1/2) which is consistent with the report by bulk samples. At the day, We will report the challenge to fabricate the Ca₂RuO₄ films which show metallic or superconductivity. We also fabricated CaRuO₃ and CaRu(O,F)₃ films. It is confirmed that the magnetic transition temperature is suppressed in the higher F-doped range.