Yoshimatsu K, Niwa M, Mashiko H, Oshima T, Ohtomo A
Department of Applied Chemistry, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan.
Materials Research Centre for Element Strategy (MCES), Tokyo Institute of Technology, Yokohama 226-8503, Japan.
Sci Rep. 2015 Nov 6;5:16325. doi: 10.1038/srep16325.
Transition metal oxides display various electronic and magnetic phases such as high-temperature superconductivity. Controlling such exotic properties by applying an external field is one of the biggest continuous challenges in condensed matter physics. Here, we demonstrate clear superconductor-insulator transition of LiTi2O4 films induced by Li-ion electrochemical reaction. A compact electrochemical cell of pseudo-Li-ion battery structure is formed with a superconducting LiTi2O4 film as an anode. Li content in the film is controlled by applying a constant redox voltage. An insulating state is achieved by Li-ion intercalation to the superconducting film by applying reduction potential. In contrast, the superconducting state is reproduced by applying oxidation potential to the Li-ion intercalated film. Moreover, superconducting transition temperature is also recovered after a number of cycles of Li-ion electrochemical reactions. This complete reversible transition originates in difference in potentials required for deintercalation of initially contained and electrochemically intercalated Li(+) ions.
过渡金属氧化物呈现出各种电子和磁相，如高温超导性。通过施加外部场来控制这种奇异特性是凝聚态物理中最大的持续挑战之一。在此，我们展示了由锂离子电化学反应诱导的LiTi₂O₄薄膜清晰的超导体 - 绝缘体转变。以超导LiTi₂O₄薄膜作为阳极形成了具有伪锂离子电池结构的紧凑电化学电池。通过施加恒定的氧化还原电压来控制薄膜中的锂含量。通过施加还原电位使锂离子插入超导薄膜中可实现绝缘状态。相反，通过对插入锂离子的薄膜施加氧化电位可恢复超导状态。此外，在多次锂离子电化学反应循环后，超导转变温度也得以恢复。这种完全可逆的转变源于最初所含锂离子和电化学插入锂离子脱嵌所需电位的差异。
