Two-dimensional electron gas and its electric control at the interface between ferroelectric and antiferromagnetic insulator studied from first principles.

A multiferroic interface between the antiferromagnetic Slater insulator SrTcO3 and ferroelectric BaTiO3 (BTO) is studied from first principles. Although the interfacial magnetoelectric coupling of SrTcO3(001) is relatively small, we found that a two-dimensional electron gas (2DEG) appears for both BaO/TcO2 and TiO2/SrO terminations. The charge character of the carriers, induced in the band gap due to polar BTO, can be switched from electrons to holes by the reversal of the electric polarization in BTO. The 2DEG is robust and stable against the degree of electronic correlations, whereas the paraelectric state of BTO suppresses the 2DEG. The origin of the 2DEG at the BTO/SrTcO3 interface and its key factors are discussed.