Multiferroic decorated FeO monolayer predicted from first principles.

Two-dimensional (2D) multiferroics exhibit cross-control capacity between magnetic and electric responses in a reduced spatial domain, making them well suited for next-generation nanoscale devices; however, progress has been slow in developing materials with required characteristic properties. Here we identify by first-principles calculations robust 2D multiferroic behaviors in decorated Fe2O3 monolayers, showcasing Li@Fe2O3 as a prototypical case, where ferroelectricity and ferromagnetism stem from the same origin, namely Fe d-orbital splitting induced by the Jahn-Teller distortion and associated crystal field changes. These findings establish strong material phenomena and elucidate the underlying physics mechanism in a family of truly 2D multiferroics that are highly promising for advanced device applications.