Neutron Laue diffraction from the magnetic structure of 4% Ga-doped FeGe₂

Laue neutron-diffraction patterns from a single crystal of 4% Ga-doped FeGe₂ at temperatures between 306 and 87 K have been recorded on neutron-sensitive image plates. The diffraction diagrams confirm that there is a paramagnetic to spiral antiferromagnetic structural change with a propagation vector 1 + δ 0 0 with δ ∼ 0.11 at ∼ 290 K, and a further change at ∼ 180 K to a 'locked-in' non-harmonic spiral phase with δ equal to exactly 1/10.