Growth and characterization of epitaxial ultrathin-Fe on BaTiO_3 films

摘要

Interfacial multiferroics have recently emerged as a promising way to circumvent the lingering scarcity of room-temperature multiferroics. First-principles calculations have predicted such interfacial multiferroics to exhibit magnetoelectric coupling and interface-induced multiferroicity, both at room temperature, if robust ferroics such as Fe and BaTiO_3 are combined together. In order to understand the physics of magnetoelectric coupling effects at the Fe/BaTiO_3 interface, a precise knowledge of the atomic-scale structural, magnetic and chemical properties is fundamental. In this paper, the growth of fully epitaxial ultrathin Fe layers on BaTiO_3 films is presented. By means of I-V measurements we demonstrate the ferroelectricity of 150 nm thick BaTiO_3 films grown by pulsed-laser deposition on La_(2/3)Sr_(1/3)MnO_3//SrTiO_3(001). Furthermore, X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurements have been acquired on epitaxial Co/Fe(2-3MLs)/BaTiO_3 structures at the Fe L_(2,3) edges, giving a direct evidence for the presence of a non-magnetic iron oxide monolayer between BaTiO_3 and the remaining layers of the ultrathin Fe, which are magnetic