Excess resistivity caused by ferromagnetic domains in pure cobalt at 4 K

Publisher Website
Google Scholar
Abstract
In uniaxial ferromagnets such as Co, the presence of domains leads to an increase of the electrical resistivity. This ’’excess resistivity’’ δρ is proportional to β2, where β is the tangent of the Hall angle at saturation. We have investigated the dependence of δρ on wall orientation relative to the current, in pure Co crystals at 4 K. The current is always normal to the easy axis. Larger electrical currents and basal fields are used to reorient the stripe domains at will. Wall orientation is checked by Bitter powder patterns at 300 K. Largest δρ is for walls normal to the current. Its value agrees with theory, and is as high as 62% of the total resistivity of the sample. We have also measured the decrease of δρ as the samples are magnetized by a field parallel to the easy axis. It does not quite follow the parabolic law predicted by theory. The discrepancy may be caused by a spatial inhomogeneity of the demagnetizing coefficient in samples having a rectangular cross section. Finally, we have studied the effect of a field normal to the easy axis, which causes a canting of spins inside each domain. The associated decrease of δρ agrees fairly well with a theory based on a one‐band model.

This publication has 2 references indexed in Scilit: