Fabrication of EuF_2 and EuO epitaxial thin films using anion-conducting substrates

摘要

Divalent europium (Eu~(2+)) compounds such as EuF_2 (band insulator and possible F~- anion conductor) and EuO (magnetic semiconductor) have attracted wide attention due to their unique magnetic and optical properties originating from in f-electron configurations. For electronics applications, it is required to fabricate them in an epitaxial thin film form. Although the fabrication of EuO epitaxial thin films has been reported using pulsed laser deposition previously, there has been no report on the fabrication of EuF_2 epitaxial thin films. Distinct from oxides, the fabrication of fluoride thin films is difficult as following reasons: (1): preparation of fluorite targets is generally difficult, and (2): fluorine gas necessary for the fluorination has toxic and corrosive properties, hindering further studies using fluoride thin films. To overcome these difficulties, here, we introduce an alternative route to use anion conducting substrates as anion sources, respectively, and report the successful fabrication of EuF2 and EuO epitaxial thin films.