Large Magnetoresistance of Isolated Domain Walls in LSMO Nanowires.

The generation, manipulation and sensing of magnetic domain walls is a cornerstone in the design of more efficient spintronic devices. Half-metals are amenable for this purpose as large low field magnetoresistance signals can be expected from spin accumulation at spin textures. However, half metals are scarce and in many case present chemical stability problems. La 1-x Sr x MnO 3 (LSMO) manganites are considered an alternative for their robust half-metallic ground state, Curie temperature above room temperature (Tc = 360 K, for x = 1/3) and chemical stability. Yet the domain wall magnetoresistance is poorly understood with large discrepancies in the reported values and conflicting interpretation of experimental data due to the entanglement of various source of magnetoresistance, namely, spin accumulation, anisotropic magnetoresistance and colossal magnetoresistance. In this work we have measured the domain wall magnetoresistance in LSMO cross-shape nanowire devices with single domain walls precisely nucleated across the current path, as confirmed by space-resolved magnetic-sensitive microscopy techniques. We find magnetoresistance values above 10% originating at the spin accumulation caused by the mistracking effect of the spin texture of the domain wall by the conduction electrons. Fundamentally, this result shows the importance on non-adiabatic processes at spin textures despite the strong Hund coupling to the localized t 2g electrons of the manganite. Moreover, the large values of the magnetoresistance in excess of 10% are high enough for encoding and reading magnetic bits in future oxide spintronic sensors. This article is protected by copyright. All rights reserved.