1. Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education & School of Physical Science & Technology Lanzhou University Lanzhou 730000 China
2. Catalonia Institute for Energy Research, IREC Sant Adrià de Besòs 08930 Barcelona Spain
3. Key Laboratory of Flexible Electronics & Institute of Advanced Materials Nanjing Tech University 30 South Puzhu Road Nanjing 211816 China
4. Institut de Ciència de Materials de Barcelona Campus de la UAB 08193 Bellaterra Catalonia Spain
5. School of Physics and Electronic Information Engineering Qinghai Normal University Xining 810008 China
6. Catalan Institution for Research and Advanced Studies, ICREA Pg. Lluís Companys 23 08010 Barcelona Spain