Measurement of the paramagnetic response function in the weak itinerant magnetic compound MnSi using polarised neutron scattering

Abstract

The polarization analysis technique is used to obtain an unambiguous separation of the magnetic contribution to diffuse neutron scattering by MnSi from other contributions. The paramagnetic response function obtained from the results is peaked in q at around 2.5 AA^-1 and has an energy width greater than 15 THz. The absolute magnitude of the response at ambient temperature is consistent with the effective moment of 2.2 mu B per manganese atom obtained from susceptibility measurements but it decreases with temperature, although a significant amount of diffuse magnetic scattering is still in the ordered phase at 9K. These results cannot be explained quantitatively in terms of either localised or itinerant models of metallic magnetism.