We discuss the properties of the triple-order-parameter (ferromagnet, ferroelectric, ferrotoroid) layered-perovskite metal Bi5Mn5O17, as predicted from first-principles calculations, in the light of a Landau expansion with trilinear coupling, with particular reference to its multiple degenerate ground states with mutually orthogonal vector order parameters, giant cross-coupling magnetoelectricity, and magnetotoroidic effects.

Keywords: Multiferroic; Metal; Ab initio calculations