Synchrotron-Radiation Photoemission Study of the Ba Atomic Layer Deposition on Multiferroic BiFeOsub3/sub

摘要

Electronic structure of ceramic BiFeOsub3O/sub surface and Ba / BiFeOsub3/sub interface has been investigated iin situ/i in an ultrahigh vacuum via synchrotron-based photoemission spectroscopy within the range of excited photon energy from 120 to 850 eV. The photo emission from the valence band and from Bi 4if, /i Fe 2ip/i, and Ba 4id/i core-levels were studied. An effect of Ba atomic layer deposition is found to induce a significant change in all spectra that is originated from the strong interaction with charge transfer between Fe, Bi surface atoms and Ba adatoms. It is obtained that the Fe 2p 3/2 core-level spectrum for the clean BiFeOsub3/sub sample contains both the Fesup2+/sup and Fesup3+/sup ion components with atomic ratio of Fesup2+/sup / Fesup3+/sup ~ 1. The Ba adsorption is found to increase the Fesup2+/sup / Fe3+ ratio up to ~ 1.5 that clearly exhibits recharge between Fesup3+/sup ↔ Fesup2+/sup ions and possibility to enhance the ferroelectric polarization.