National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei 230029 People's Republic of China.
Nano Lett. 2014 Jul 9;14(7):4036-43. doi: 10.1021/nl501480f. Epub 2014 Jun 25.
Tuning the metal insulator transition (MIT) behavior of VO2 film through the interfacial strain is effective for practical applications. However, the mechanism for strain-modulated MIT is still under debate. Here we directly record the strain dynamics of ultrathin VO2 film on TiO2 substrate and reveal the intrinsic modulation process by means of synchrotron radiation and first-principles calculations. It is observed that the MIT process of the obtained VO2 films can be modulated continuously via the interfacial strain. The relationship between the phase transition temperature and the strain evolution is established from the initial film growth. From the interfacial strain dynamics and theoretical calculations, we claim that the electronic orbital occupancy is strongly affected by the interfacial strain, which changes also the electron-electron correlation and controls the phase transition temperature. These findings open the possibility of an active tuning of phase transition for the thin VO2 film through the interfacial lattice engineering.
通过界面应变来调整 VO2 薄膜的金属-绝缘体转变（MIT）行为对于实际应用是有效的。然而，应变调制 MIT 的机制仍存在争议。在这里，我们通过同步辐射和第一性原理计算直接记录了 TiO2 衬底上超薄 VO2 薄膜的应变动力学，并揭示了其内在的调制过程。结果表明，通过界面应变可以连续调节所得到的 VO2 薄膜的 MIT 过程。从初始薄膜生长开始，建立了相变温度与应变演化之间的关系。从界面应变动力学和理论计算来看，我们声称电子轨道占据强烈受到界面应变的影响，这也改变了电子-电子相关，并控制了相变温度。这些发现为通过界面晶格工程对薄 VO2 薄膜的相变进行主动调谐提供了可能。
