Large Magnetoresistance of Isolated Domain Walls in La2/3 Sr1/3 MnO3 Nanowires

Abstract

Generation, manipulation, and sensing of magnetic domain walls are cornerstones in the design of 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. Among half metals, La_{1- x} Sr_x MnO₃ (LSMO) manganites are considered as promising candidates for their robust half-metallic ground state, Curie temperature above room temperature (T_c = 360 K, for x = 1/3), and chemical stability. Yet 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, the domain wall magnetoresistance is measured in LSMO cross-shape nanowires with single-domain walls nucleated across the current path. Magnetoresistance values above 10% are found to be 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. These large magnetoresistance values are high enough for encoding and reading magnetic bits in future oxide spintronic sensors.

Keywords: domain wall resistance; magnetoresistance; manganites; nanomagnetism; spintronics.