Route to achieving giant magnetoelectric coupling in BaTiO3/Sr2CoO3F perovskite heterostructures

Polarization-induced spin switching of atoms in magnetic materials opens the possibilities to design and develop advanced spintronic devices, in particular, storage devices where the magnetic state can be controlled by an electric field. We employ density functional theory calculations to study the magnetic properties of a perovskite strontium cobalt oxyfluoride ${\mathrm{Sr}}₂{\mathrm{CoO}}₃\mathrm{F}$ (SCOF) in a hybrid perovskite heterostructure, where SCOF is sandwiched between two ferroelectic ${\mathrm{BaTiO}}₃$ (BTO) layers. Our calculations show that the spin state of the central Co atom in SCOF can be controlled by altering the polarization direction of the BTO, specifically, to switch from a high-spin state to a low-spin state by changing the relative orientation of the ferroelectric polarization of BTO with respect to SCOF, leading to an unexpected, giant magnetoelectric coupling, ${\ensuremath{\alpha}}_s\ensuremath{\approx}21\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\phantom{\rule{0.28em}{0ex}}{\mathrm{G}\phantom{\rule{0.16em}{0ex}}\mathrm{cm}}²/\mathrm{V}$.