Interface electronic structures of BaTiO3@X nanoparticles (X=gamma-Fe2O3, Fe3O4, alpha-Fe2O3, and Fe) investigated by XAS and XMCD

Abstract

The electronic structures of BaTiO3@X (core@shell) nanoparticles (X=gamma-Fe2O3, Fe3O4, and Fe) have been investigated by employing soft x-ray-absorption spectroscopy and x-ray magnetic circular dichroism (XMCD). It is found that the valence states of Ti ions near interfaces are formally tetravalent (Ti4+:3d(0)) and that the valence states of Fe ions in shells are essentially the same as those of the corresponding bulk materials, with some disorder in the site occupations for X=gamma-Fe2O3 and Fe3O4. The negligible Ti 2p XMCD signals were observed, indicating that the induced spin polarization of the interface Ti 3d electrons is negligible in BaTiO3@X nanoparticles.