Coupling between improper ferroelectricity and ferrimagnetism in the hexagonal ferrite LuFeO3

Abstract

Here, we propose an idea to realize noncollinear ferrimagnetic orders with a considerably high magnetization M and their coupling with an improper ferroelectric (FE) order in hexagonal LuFeO3 type systems which exhibit interesting topological orders. These magnetic and magnetoelectric phenomena are driven by the antisymmetric Dzyaloshinskii-Moriya interactions between the magnetic ions and their coupling with the ferroelectricity. The proposed two-sublattice magnetic system, generated by a specific charge-ordered state, forms multiple energetically close, noncollinear ferrimagnetic orders. This offers a platform to manipulate the microscopic magnetic interactions and to trigger spin-reorientation (SR) transitions by various efficient means. The two-sublattice structure was realized in the hexagonal phase of LuFeO3 doped with electrons. The proposed electron-doped systems are expected to exhibit switchable electric polarization (P∼6-15 μC/cm2), considerably high magnetization (M∼1.1-1.3μB/Fe), and magnetic transition near room temperature (∼275-290K). Based on the coupling between the magnetic interactions and the FE primary order parameter observed in this system, microscopic mechanisms to achieve electric field E induced SR transitions and 180∘ switching of the direction of M are discussed.