Magnetic and transport behavior of quasi two-dimensional MnO₂ monolayer
Heng-Jui Liu1,2*, Jheng-Cyuan Lin1,5, Qing He3, Rong Huang4, Bo-Chao Huang2, Jing-Ching Wang2, Yue-Wen Fang4, Chun-Gang Duan4, Ya-Ping Chiu2, Ying-Hao Chu1,5
1Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan
2Department of Physics, National Taiwan Normal University, Taipei, Taiwan
3Department of Physics, Durham University, Durham, UK
4Key Laboratory of Polar Materials and Devices Ministry of Education, East China Normal University, ShangHai, China
5Institute of Physics, Academia Sinica, Taipei, Taiwan
* presenting author:Heng-Jui Liu,
Among numerous kinds of two-dimensional (2D) materials, another quickly arising branch based on the complex oxide heterostructures offers more opportunities in manipulating of spin, charge, orbit, or lattice degrees of freedom via precisely controlling the atomic surficial and interfacial terminations. In past decades, many intriguing physical properties such as interface superconductivity, interface ferromagnetism, 2D electron gas (2DEG), etc. were discovered by growing high quality epitaxial films on the substrates with specifically terminated surface structures. In this work, a novel concept of fabrication process using perovskite materials will be proposed based on the control of single surface termination and the layer-by-layer growth process, which can develop large-scale, single crystal 2D materials. The manganites systems were chosen as model system since their magnetic behavior are highly dependent on the charge and orbital ordering on the MnO₂ plane. By varying the subsequently deposited capping materials (SrTiO₃ or LaAlO₃), we can even modulate the valence state and magnetic properties of these monolayers. Further calculation carried out by Density Functional Theory (DFT) indicates the possible presence of half-metal behavior in these MnO₂ monolayers while capped LaAlO₃ layer. Interestingly, the MnO₂ with LaAlO₃ capping layer simultaneously exhibits a large photoresponse, which has variation of 2265% when illuminated by light with wavelength of 325nm and power density of 18.5W/cm².

Keywords: Monolayer, 2 dimensional material, MnO2