Valence Imbalance of Manganese Ions between Surface and Bulk Enhanced by Fermi-Surface Structure in Layered Manganites

TMU International Symposium on "New Quantum Phases Emerging from Novel Crystal Structure"

Yamamura, Ryosuke^1 ; Hotta, Takashi^1

Department of Physics, Tokyo Metropolitan University, Tokyo, Hachioji

192-0397, Japan^1

关键词: Charge structure;    Double exchange models;    Electron systems;    Friedel oscillations;    High-efficiency;    Layered manganite;    Manganese ions;    Spin structures;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/683/1/012042/pdf
DOI  :  10.1088/1742-6596/683/1/012042

来源: IOP

【 摘 要 】

To investigate valence imbalance phenomena between the surface and bulk in layered manganites, we analyze an eg-orbital degenerate double-exchange model with surfaces for two types of t2gspin structures. We reconfirm that the surface-induced Friedel oscillations occur in the charge structure and that the number of Mn4+ions on the surface is larger than that in the bulk. This tendency is found to be more significant, when the eg-electron system has Fermi-surface structures with better nesting properties. The behavior of the Friedel oscillations depends on the nesting properties of the Fermi-surface curves along the direction of the oscillations, and not on the dimension of the system itself. We believe that these results will be useful for the development of high-efficiency cathodes in Li-ion batteries and catalysts.