HIGH-TEMPERATURE SPIN-DENSITY OF FECO - EFFECT OF LATTICE-VIBRATIONS ON THE ELECTRON-DISTRIBUTION

The magnetic structure factor of equi-atomic FeCo in the disordered ph ase has been measured at 1000 K by coherent scattering of polarized ne utrons. The overall shape of the magnetization distribution exhibits m arked variations when compared with the room-temperature distribution. The analysis of the spin density asphericity shows that such an effec t cannot be ascribed to a change in the electron distribution in the d isordered phase, whereas a correct treatment of the thermal motion of nuclei, inducing a deformation of the electron distribution, takes int o account the observed behaviour.