Synthesis, structure and magnetic properties of β-MnO 2 nanorods

Abstract

We present synthesis, structure and magnetic properties of structurally well-ordered single-crystalline β-MnO2 nanorods of 50-100 nm diameter and several μm length. Thorough structural characterization shows that the basic β-MnO2 material is covered by a thin surface layer (2.5 nm) of α-Mn2O3 phase with a reduced Mn valence that adds its own magnetic signal to the total magnetization of the β-MnO2 nanorods. The relatively complicated temperature- dependent magnetism of the nanorods can be explained in terms of a superposition of bulk magnetic properties of spatially segregated β-MnO2 and α-Mn2O3 constituent phases and the soft ferromagnetism of the thin interface layer between these two phases.