Magnetic-domain structure ofNi1−xMnxfilms inferred from resistance fluctuations

In films of partially ordered ${\mathrm{Ni}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{\mathit{x}}$, with x≊0.28, large electrical-resistance noise from magnetic effects was found. Individual fluctuating domains with large volumes but low magnetic moments were observed. These domains are apparently clusters of constituent ferromagnetic domains which have a net systematic antiferromagnetic alignment. The clusters are larger in the ‘‘reentrant spin-glass’’ regime than in the ferromagnetic regime. Ferromagnetic domains arranged in antiferromagnetic stripes were also imaged by scanning electron microscopy.