Controlling the Electrical and Magnetoelectric Properties of Epitaxially Strained Sr₁₋<i>_x</i>Ba<i>_x</i>MnO₃ Thin Films

Abstract

The perovskite (Sr,Ba)MnO 3 system is an ideal candidate for tailoring electrical and magnetoelectric properties through the accurate control of Ba content and epitaxial strain due to the strong coupling between polar instability, spin order, and lattice. Here, first, the polar order is proved to be induced in Sr 1− x Ba x MnO 3 thin films through lattice expansion either by epitaxial strain or chemical pressure, which correlates with the evolution of the dielectric properties. Second, due to strong spin–phonon coupling, a large magnetoelectric response is found in the (Sr,Ba)MnO 3 system, in which the dielectric constant drops up to 50% when the antiferromagnetic order emerges, larger than most magnetoelectric oxides. More important, this coupling between magnetism and dielectric properties can be tuned from ≈18% to ≈50% by appropriately selecting Ba content and epitaxial strain. Third, a clear trend of increasing the band gap energy on increasing the unit cell volume either by epitaxial strain or chemical pressure is found, which opens the way for engineering the semiconducting properties of (Sr,Ba)MnO 3 system at will. Thus, this work proves the possibility to design the electrical response and the magnetoelectric coupling in (Sr,Ba)MnO 3 system.