Emergence of anomalous magnetoresistance at low temperatures in Co/Cu nanomultilayers

Abstract

Magnetic nanomultilayers are promising for spintronic applications owing to their strong response to external stimuli, yet the temperature dependence of their magnetoresistance remains insufficiently explored. Here, Co/Cu nanomultilayers with varying widths were fabricated, and the temperature dependence of their magnetoresistance was systematically characterized. Under cyclic magnetic fields, the magnetoresistive response exhibits a pronounced temperature dependence. At high temperatures (≥250 K), the resistance–field (R–H) curves are nearly symmetric, whereas at low temperatures, plateau- and kink-like features emerge in the negative field region, with the kink shifting toward higher fields upon cooling. This symmetry breaking is attributed to the interplay among domain-wall pinning, spin scattering, and thermal activation: Suppressed thermal activation at low temperatures enhances pinning and induces abrupt spin scattering, while at higher temperatures, thermal activation weakens pinning, allowing smooth domain-wall motion. These results demonstrate a strong coupling between domain evolution and spin transport, providing insights into the design of high-sensitivity magnetoresistive devices and asymmetric spin logic applications.