Influence of demagnetizing effect on the shape and broadening of magnetoresistance curves

Abstract

It was observed in recent magnetoresistance studies on elongated strip-shaped thin foil samples that the MR(H) hysteresis curves have different shapes and widths in the longitudinal (L) configuration (field H parallel with the measuring current) and in the transverse (T) configuration (field H transverse to the measuring current). Subsequent magnetic measurements [L.F. Kiss et al., Eur. Phys. J Plus 139, 844 (2024)] of similar strip-shaped samples taken with different field orientations (corresponding either to the LMR or TMR configurations of the magnetoresistance measurements) revealed differences also in the M(H) magnetization curves, which are attributed to demagnetizing effects. After correcting for the demagnetizing field, the transverse M(H) curves could be brought in fairly good overlap with the measured longitudinal M(H) curves. In the present work, results of MR(H) measurements are reported on strips of the same Ni-Co alloys and pure Ni metal which were used in the M(H) study. Based on this recent work on the M(H) curves, one can now explain the differences in the shape and width of the LMR(H) and TMR(H) curves of a given material in a fully quantitative manner by taking into account the demagnetizing effects. Similarly to the transverse M(H) curves, the TMR(H) curves could also be corrected for the demagnetizing field, yielding good agreement with the LMR(H) curves. Furthermore, whereas the LMR(H) curves exhibited a normal hysteresis corresponding to the hysteresis behavior of the M(H) curve, the TMR(H) curves showed an anomalous behavior which can also be ascribed to demagnetizing effects. The same holds true also for the polar magnetoresistance curves PMR(H) measured in a magnetic field perpendicular to the strip plane.