Abstract
The aim of this experiment was to investigate the temperature dependence of the spin density of the Invar system Fe65Ni35 via measurements on a single crystal using magnetic Compton scattering. We made measurements of the spin density resolved along the [100] and [110] crystallographic directions. The temperature dependence exhibited a subtle change in the momentum density. Interestingly, the momentum distribution of the spin moment was different for the two crystallographic directions. It would appear that increasing temperature has a complicated effect on the contributions of the electrons from different orbitals, rather than just causing a change in the amount of delocalisation. This change requires further investigation, particularly with further compositions being studied in order to determine whether the change in electronic structure can be correlated with the existence of the Invar effect.
