Tailoring magnetic properties of α-MnO2@NiCo2O4 core/shell nanostructure

Herein, we present a bi-magnetic hierarchical alpha-MnO2@NiCo2O4 core-shell nanostructure synthesized through a simple two-step hydrothermal process. The structural and morphological properties of these core-shell nanostructures were studied systematically using X-ray diffraction and Field emission scanning electron microscope. The XRD patterns are concomitant with the presence of the two phases, and the formation of nanowire@nanosheet is confirmed by the SEM/EDX study. FTIR measurement results give an idea about the vibration and bond formation of the samples, while the optical properties of the samples examined through UV-visible spectroscopy suggest the presence of a spinel group along with the MnO2 phase in the absorption spectra. The results of magnetic measurements reveal the spin-glass type behavior at very low temperature i.e., 8 K, and the saturation magnetization for the core-shell system was found to be 50 emu/g. Experimental evidence for this spin glass behavior was confirmed by the studies of memory cycles and the relaxation dynamics in thermal variation of the magnetization process.