Fig. 1: Classification of Fe-pnictide heterointerfaces.
From: Engineering of Fe-pnictide heterointerfaces by electrostatic principles
The structural unit of the [Fe2As2] layers has a net charge of QL = −2 and a dipole moment, µL ≠ 0. Examples of originally compensated interfaces include a Ba(Fe1-xCox)2As2/Fe, b Ba(Fe1-xCox)2As2/BaFe2As2 (hypothetical), and c LnOFeAs/BaFe2As2 (this work). Here, the interface is within the Fe plane (black arrow). Examples of originally uncompensated interfaces that develop an interfacial layer include Ba(Fe1-xCox)2As2/SrTiO3 d with TiO2 termination and e with SrO termination, f Ba(Fe1-xCox)2As2/(La,Sr)(Al,Ta)O3, and g Ba(Fe1-xCox)2As2/MgO. Compensation is achieved by the valence change within the interfacial layer or by developing a metallic interfacial layer.
