Non equilibrium magnetization in antiferromagnetically coupled [Fe/Cr]10 multilayers on large time scales

Ultra slow nonequilibrium magnetization dynamics in epitaxial antiferromagnetically coupled [Fe/Cr(0 0 1)](10) has been studied at temperatures down to 50 mK by using giant magnetoresistance. Measurements, carried out in magnetic fields up to 90 kG show, depending on the magnetic field, temperature and magnetic history, a coupled domain rotation or slow logarithmic relaxation followed by avalanches or transition to chaotic noise regime. (C) 2003 Elsevier B.V. All rights reserved.