Magnetic dead layer in ferromagnetic manganite nanoparticles

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.