A neutron diffraction investigation of the sinusoidal atomic displacement wave in pure chromium

Abstract

A neutron diffraction investigation on a single crystal of chromium, which is approximately single- Q, confirms the existence of a sinusoidal atomic displacement wave in the antiferromagnetic state. The wave is observed to be polarized parallel to the spin density wave (SDW) wavevector, Q, and to have a wavevector 2 Q in both the transversely and longitudinally polarized SDW phases. The amplitude of the displacement wave is found to be proportional to the square of the amplitude of the SDW. We obtain for the displacement wave amplitude (0.0017 ± 0.0002) a at 130 K, where a is the lattice parameter.