Dragging of stripe domains by a temperature gradient in Metglas 2826 MB (invited)

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Abstract
A steady, collective, translation of all domains has been observed in field-annealed samples subjected to a temperature gradient dT/dx≡102 K/mm. The square samples, of size 1 mm×1 mm×25 μm, are held at one end by a water-cooled copper clamp, while the opposite end is located 0.1 mm from a thin, electrically heated, nichrome wire. Observations by longitudinal Kerr contrast show that the walls move from the hot to the cold end. We use a 60 Hz magnetic field HE parallel to the induced easy axis, to decrease the effective coercivity and facilitate wall motion. A reversal of the sign of dT/dx is found to cause a reversal of the sense of wall motion. Hydromagnetic forces originating from the Nernst-Ettingshausen effect are probably responsible for this ’’thermal domain-drag’’ motion. We extend the existing theory to the case of isolated plane walls. The shape of the boundary surrounding the region of moving walls in the (dT/dx,HE) plane is explained in terms of the non-zero size xc≡2 μm of the potential wells describing wall pinning. In addition, we review the experimental situation concerning the dragging of domains by an electric current in amorphous Gd-Co-Mo and Gd-Co-Au films, and in Co single crystals.