Coexistence of glassy antiferromagnetism and giant magnetoresistance   (GMR) 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 (GAF) phase. This phase reflects the influence of interlayer exchange coupling (IEC) at low temperature (T < 140K) 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" (AT) 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. 
N. Theodoropoulou, A. F. Hebard, M. Gabay, A. K. Majumdar, C. Pace, J.   Lannon, D. Temple