Coexistence of glassy antiferromagnetism and giant magnetoresistance in Fe/Cr multilayer structures

Using temperature-dependent magnetoresistance and magnetization measurements on Fe/Cr multilayers that exhibit pronounced giant magnetoresistance (GMR), we have found evidence for the presence of a glassy antiferromagnetic phase. This phase reflects the influence of interlayer exchange coupling (IEC) at low temperature (To140 K) and is characterized by a field-independent glassy transition temperature, Tg; together with irreversible behavior having logarithmic time dependence below a ‘‘de Almeida and Thouless’’ critical field line. At room temperature, where the GMR effect is still robust, IEC plays only a minor role, and it is the random potential variations acting on the magnetic domains that are responsible for the antiparallel interlayer domain alignment. r 2003 Elsevier Science B.V. All rights reserved.