Strain is a leading candidate for controlling magnetoelectric coupling in multiferroics. Here, we use x-ray diffraction to study the coupling between magnetic order and structural distortion in epitaxial films of the orthorhombic ($o$-) perovskite ${\mathrm{LuMnO}}_3$. An antiferromagnetic spin canting in the $E$-type magnetic structure is shown to be related to the ferroelectrically induced structural distortion and to a change in the magnetic propagation vector. By comparing films of different orientations and thicknesses, these quantities are found to be controlled by $b$-axis strain. It is shown that compressive strain destabilizes the commensurate $E$-type structure and reduces its accompanying ferroelectric distortion.

• Received 23 January 2014

DOI:https://doi.org/10.1103/PhysRevLett.113.167202