Identification of large Jahn-Teller distortion of antisite in ABO3 perovskite and persistent photorefractivity
Ho-Hyun Nahm and Chul Hong Park
Pusan National University
The photorefractivity (PR) was discovered in LiNbO3 in 1966, and then in many other perovskite oxides1. The PR is suggested to be based on the space modulation of photocurrents through charge-transfer from illuminated to dark area by nonuniform illumination. The generation of photocurrent depends on the presence of suitable impurities or defects. Of particular interest is information on the centers supplying charge carriers, on the trapping centers, and on optical excitation. The persistent photorefractivity in ABO3-type perovskites has been extensively investigated because of its application to the optical holographic memory with terra-bit capacity and nonlinear optical devices10. In spite of the recent significant technical achievement for the long-time persistent robust PR, the microscopic structure responsible for the PR is not yet identified. We identified a large Jahn-Teller distortion of B-antisite in LiNbO3, accompanied with a significant change of the electronic structure: a deep-to-shallow transition. Based on the calculational results, the microscopic mechanism of the persistent PR and related phenomena are discussed.