The specific behavior of MxTiS2 (x=1/4, M=Fe, Ni) surfaces probed by scanning microscopy (STM and AFM)
Résumé
The scanning tunneling microscopy (STM) and atomic force microscopy (AFM) images of two model systems M 1=4 TiS 2 (M ¼ Fe, Ni) were interpreted on the basis of the partial electron density qðr; E F Þ and total electron density qðrÞ of a slab which consists of seven (0 0 1) M 1=4 TiS 2 atomic layers. The geometrical structure of the slabs investigated was optimized. Electronic structure calculations were performed using the ab initio periodic LCAO-DFT method. The top sulfur plane (0 0 1) imaged gives a different answer depending both of the compounds considered and the scanning probe microscopic instrument used. Theoretical calculations have then been carried out in order to improve our knowledge of the surface electronic structure of these inserted compounds and attempts are made to rationalize the experimental data. A specific behavior of the surface electronic structure in comparison with the 3D compounds (depending on the guest specie inserted) is shown.
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