AFM order in BFO was first detected by neutron diffraction and was classified as Type G. However, the spins are not perfectly antiparallel; there is a spatial-modulated spin cycloidal structure with an incommensurate period of 64nm. This proposal aims to answer the following questions:1. How does the cycloid wavelength evolve with temperature field?2. Is there a reorientation of the cycloid direction when the electric field is applied? 3. Is the degeneracy between the different crystallographic orientations of the cycloid vector lifted? 4. Does the tuning of the spin order offer a way to achieve strong magnetoelectric coupling?Answers will be found by performing a GiSANS experiment on a [111] oriented BFO, to measure how the cycloid length scale changes under and applied electric field and temperature.