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We report the synthesis of rare-earth manganese-oxide-based nanotubes. The pore wetting technique was used to obtain structures of nominal composition La0.325Pr0.300Ca0.375MnO3 with 800 nm external diameter, 4000 nm length, and wall thickness below 100 nm exhibiting magnetic and magnetoresistive behavior below 200 K, including nonvolatile memory. Walls are found to be formed by small crystals of approximately 20 nm. Structures obtained using different diameter of pores, as small as 100 nm, have a similar aspect ratio. Results show the realization of nanotubes of manganites exhibiting intrinsic phase separation.

We present experimental evidence on the physical origin of a magnetic dead layer (MDL) in manganite nanoparticles. The studied nanoparticles constitute the wall of La0.67Sr0.33MnO3 and La0.67Ca0.33MnO3 manganite nanotubes. Magnetic properties analysis and high resolution transmission electron microscopy show a shell of approximately 2 nm thickness with different properties from the core. In this shell the atoms are in a noncrystalline array that perfectly explains the 50% reduction of the magnetization compared to the bulk. Moreover, we present experimental evidence that the internal magnetic structure of the MDL is constituted by small ferromagnetic clusters in a frustrated configuration.

We present magnetic and transmission electron microscopy experiments on the double-exchange compound La2∕3Sr1∕3MnO3, nanostructured to form tubes with 700 nm of external diameter. Microscopy reveals that their walls are formed by a compact agglomerate of grains, whose sizes are around 20 nm. The study of magnetic properties of randomly oriented nanotubes shows that the transition from the ferromagnetic to paramagnetic state is at TC=320K, close to the bulk sample value. They exhibit hysteresis in magnetic field loops. The coercive field at 90 K is around 130 Oe, and estimated single-domain size is around 20 nm.