Critical magnetic scattering in invar Fe 65 Ni 35 alloy

A critical small angle polarized neutron scattering experiment on invar Fe65Ni35 alloy was performed in the magnetic field H of value from 10 to 1000 G using a special ‘inclined’ geometry (H is inclined to the wave vector k). Two contributions to the critical scattering were studied in the temperature range TC±0.1TC: first, the two-spin correlation function with its amplitude and the correlation length RC(T,H ) and, second, the three-spin dynamical spin-correlation function, by extracting an asymmetric part of the polarization-dependent scattering. The data are interpreted in terms of static and dynamic scaling theory.