1. Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linköping University, Linköping SE-581 83, Sweden
2. Department of Materials Science and Applied Mathematics, Malmö University, Malmö SE-205 06, Sweden
3. Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
4. Guangdong Provincial Key Laboratory of Functional Oxide Materials and Devices, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China