Magnetoresistive La$_{0.67}$Sr$_{0.33}$MnO$_3$ Nanowires

We report the synthesis of novel La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ (LSMO) nanowires and the observations of intriguing magnetoresistance phenomena. These nanowires were synthesized by depositing an epitaxial shell of LSMO onto MgO nanowires, thereby rendering single-crystalline MgO/LSMO core-shell structures. Transport studies on these nanowires have revealed a remarkable metal-insulator transition at 325 k, accompanied by room-temperature colossal magnetoresistance $\sim $ 10{\%} under a one-Tesla magnetic field. In addition, anisotropic magnetoresistance was observed at room temperature with a 1.4{\%} resistance variation between magnetic fields parallel and perpendicular to the nanowire. Furthermore, polycrystalline LSMO have been obtained by tuning the synthesis condition, leading to a low-field magnetoresistance up to 16 {\%} at 0.06 T. This is attributed to the spin-dependent scattering of polarized electrons at the grain boundaries, with underlying physics similar to the giant magnetoresistance. Our study demonstrates the advantages of one-dimensional magnetic oxide nanowires and may lead to novel applications in the near future.