Size-controlled synthesis and magnetic properties of copper germanate nanorods. Observation of size-induced quenching of the spin-Peierls transition

Abstract

CuGeO₃, a quasi-one-dimensional S = 1/2 antiferromagnet, is the first inorganic material to display a spin-Peierls transition (SP) in which the lattice of the S = 1/2 antiferromagnetic 1-D chain system undergoes dimerization below the transition temperature to give a singlet ground state. The size-dependent magnetic properties and SP transitions of CuGeO₃ are little understood. In this paper, we report the size-controlled synthesis of CuGeO₃ nanorods by a hydrothermal method via adjustment of the reaction conditions. The size-effect on their magnetic properties has been investigated. In smaller crystalline CuGeO₃ nanorods (ca. <600 nm length), the SP transition is found to be quenched, demonstrating that the magnetoelastic coupling is blocked in these small nanorods. By contrast, longer CuGeO₃ nanorods (~600 nm to >2 μm length) show a weak SP transition. These findings demonstrate that size tuning is an effective tuning parameter for controlling the ground state properties of CuGeO₃ and other magnetic materials where spin–lattice interactions are important.