Evidence of spin-wave demagnetization in Fe-Cr giant magnetoresistance multilayers

摘要

The temperature dependence of the saturation magnetization of Xe ion-beam sputtered Fe-Cr multilayers has been measured between 5 and 300 K in the presence of a field greater than the saturation field (H_(sat)). With the application of H_(sat), the zero-field antiferromagnetically coupled ferromagnetic Fe layers are forced to align ferromagnetically. We find that the thermal demagnetization of such magnetically composite structure follows the Bloch formula for spin waves with anharmonic term in the magnon dispersion relation, viz., M(T)=M(0)[1 +AT~(3/2)+BT~(5/2)]. Comparisons are presented between the multilayers and bulk crystalline Fe.