Temperature dependent optical properties of LaCoO3/SrTiO3 thin film studied by spectroscopic ellipsometry
Qiao Chen,
Xiangqi Wang,
Min Zhang,
Zilong Xu,
Junbo Gong,
Azizur Rahman,
Lele Fan,
Rucheng Dai,
Zhongping Wang,
Zengming Zhang
Affiliations
Qiao Chen
CAS Key Laboratory of Strong-Coupled Quantum Matter Physics and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
Xiangqi Wang
CAS Key Laboratory of Strong-Coupled Quantum Matter Physics and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
Min Zhang
CAS Key Laboratory of Strong-Coupled Quantum Matter Physics and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
Zilong Xu
CAS Key Laboratory of Strong-Coupled Quantum Matter Physics and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
Junbo Gong
CAS Key Laboratory of Strong-Coupled Quantum Matter Physics and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
Azizur Rahman
CAS Key Laboratory of Strong-Coupled Quantum Matter Physics and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
Lele Fan
Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Yangcheng, Jiangsu 224051, China
Rucheng Dai
The Center of Physical Experiments, University of Science and Technology of China, Hefei 230026, China
Zhongping Wang
The Center of Physical Experiments, University of Science and Technology of China, Hefei 230026, China
Zengming Zhang
CAS Key Laboratory of Strong-Coupled Quantum Matter Physics and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
We report the spectroscopy ellipsometry study for LaCoO3 epitaxy thin films grown on different SrTiO3 substrates [LCO/STO(001) and LCO/STO(111)]. Reciprocal space mapping measurements show that the as-prepared LCO/STO films are fully strained at the interface. The optical constants (the refractive index and the extinction coefficient) of LCO films from 300 K to 800 K are obtained based on the ellipsometry measurements. The optical absorption at the near-infrared region increases with heating and sharply enhances around 500 K due to the occurrence of insulator–metal transition. The observed isosbestic point reveals the evolution of the band structure along with the insulator–metal transition. The red shift of the isosbestic point from the (001) sample to the (111) sample indicates the important role interfacial strain plays in affecting the spin states. We also provide the optical conductivity and the relative effective number of interband transition electrons for different energy regions.
