According to some recent studies, the magnetoresistance curves of ferromagnetic strip-shaped
samples can significantly differ depending on whether the in-plane external applied
magnetic field H is oriented in parallel to either the long or the short edge of the
strip. To address this problem, in the present work magnetization curves M ( H ) were
measured for similarly shaped samples with both magnetic field orientations used in
the magnetoresistance measurements. It was found that the M ( H ) curves strongly
depend on the saturation magnetization and shape of the samples as well as on the
magnetic field orientations. For some samples with sufficiently large saturation magnetization,
the effective demagnetizing factors could be deduced from the measured M ( H ) curves.
By considering the investigated samples as a ferromagnetic slab, and approximating
them with a general ellipsoid, the demagnetizing factors were calculated from known
formulae and compared to the experimental values. A fairly good matching was observed,
although the latter data were systematically slightly larger, certainly due to the
not completely homogeneous magnetization within the rectangular slab as opposed to
the case of a general ellipsoid. The differences in the M ( H ) curves for the two
orientations of the magnetic field could be completely attributed to demagnetizing
effects.
