Atomic replacement effects on the band structure of doped perovskite thin films

S. L. CHENG^1,3, C. H. Du², T. H. CHUANG³, Jauyn Grace Lin^1,4*

¹Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan
²Department of Physics, Tamkang University, Taipei, Taiwan
³Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan
⁴Center for Atomic Initials for New Materials, National Taiwan University, Taipei, Taiwan

* Presenter:Jauyn Grace Lin, email:jglin@ntu.edu.tw

The potential applications of perovskite manganite R_1-xA_xMnO₃ (R = rare earth element; A = Sr, Ca) thin films have been continuously explored due to their multi-functional properties. In particular, the optimally hole-doped La_2/3Sr_1/3MnO₃ thin film demonstrates a colossal magneto-resistance that is beneficial to the performance of spintronic devices. To understand the effect R and A ions on the physical properties, we systematically measure the electrical, magnetic and electronic states for three optimally doped R_0.67A_0.33MnO₃ thin films with R = La, Sm, A = Sr, Ca. Various energy parameters are derived based on the X-ray absorption and X-ray photoelectron spectra, including the band gap, the charge frustration energy and the magnetic exchange energy. It is interesting to find that the replacement of La with Sm is more effective than that of Sr with Ca in terms of tuning the band gap, which is attributed to the significant reduction of the O 2p- Mn 3d hybridization due to interfacial strain. The results of this study provide useful information for the band design of perovskite oxide films.

Keywords: band gap, interfacial strain, XAS, perovskite