SEGREGATION AND SPEROMAGNETIC ORDER IN AMORPHOUS TB0.18SI0.82 DETECTED BY NEUTRON-SCATTERING AT SMALL AND LARGE ANGLES

Amorphous Tb0.18Si0.82 has been investigated at low temperatures by ne utron diffraction (ND) and small angle neutron scattering (SANS). Belo w the magnetic ordering temperature, magnetic ND rings are observable between the nuclear rings, but no magnetic SANS is detectable at low q (q = 4pi sin theta/lambda) values where nuclear SANS is intense. From these observations and the comparison with the antiferromagnetic orde r in crystalline TbSi1.67 alloy, a phase segregation and a speromagnet ic order in amorphous Tb0.18Si0.82 with magnetic moment values of abou t 4mu(B)/Tb and compensation of the magnetic moments over very small d istances are proposed.