Ferroelectricity-induced interfacial ferromagnetism in non-magnetic heterostructures*

We show, through deliberate interfacial electronic structure modification, ferroelectricity induced room-temperature interfacial ferromagnetism with perpendicular magnetic anisotropy in Pt at the Pt/BaTiO₃ interface in a nominally non-magnetic Pt/BaTiO₃/SrTiO₃ (001) heterostructure. The average magnetic moment of a 2 nm Pt thin film on 20 unit cells of BaTiO₃ at 300 K is ~0.4 m_B/Pt. Our first-principles calculations, as well as scanning transmission electron microscopy measurements indicate that the interfacial electronic structure modification induced by the polarization of BaTiO₃ and Pt substitution of Ti at the Pt/BaTiO₃ interface is responsible for the unusual ferromagnetism in Pt. The general concept of interfacial electronic structure modification provides an innovative route to induce interfacial room-temperature ferromagnetism in a nominally non-magnetic material.

In collaboration with Bénédicte Warot-Fonrose, N. L. Yakovlev, C. J. Li, S. W. Zeng, Z. Huang, K. Han, Z. S. Lim, J. M. D. Coey