MAGNETIZATION REVERSAL IN BICRYSTAL MEDIA

Intergranular interactions and time dependence effects have been studi ed in CoCrPt/Cr thin films with two different Cr concentrations and di fferent physical grain sizes. The samples have a bicrystal structure i n which Co alloy grains, grown onto a Cr underlayer have subgrains wit h orthogonal c-axes. It was found via the Delta I method that exchange coupling was predominant in all the films along the circumferential d irection. The samples with higher Cr concentration exhibited lower exc hange coupling as indicated by the value of d(Delta I)max/dH which was found to correlate with the integrated medium noise. The study of the time dependence effects revealed that higher Cr concentration caused a reduction in activation volumes indicating a higher degree of segreg ation in the grain boundaries of the films. A correlation is reported between the activation volumes and the domain images of the samples in the ac demagnetized state. (C) 1997 American Institute of Physics.