Abstract:We propose two separate experiments to determine the magnetic structures of multiferroic and strained o-ReMnO3 (Re=Lu,Tb) thin films grown on YAlO3 substrates. In the first experiment, we request to use D10 in order to both identify and measure the strongest Bragg peaks due to the long-range symmetry-breaking antiferromagnetic (AFM) order in each film. Using this information, we request to subsequently use D3 with CryoPAD in order to conduct a spherical neutron polarimetry study of the strongest AFM peaks in each film. This second experiment is only made possible by recent pioneering technical developments at ILL where a unique zero-field four-circle device for CryoPAD provides in-situ control of the sample orientation, and hence of the magnetic interaction vector. From these experiments we aim to determine unambiguously both the magnetic structures in the strained thin films, and also the intrinsic magnetic domain populations. The latter result will show how the strain in the films may emerge as an effective tuning parameter for the magnetic and electric properties of the films.