Growth of an ordered array of oriented manganite nanowires in alumina templates

Abstract

We report the growth of oriented nanowires of manganites within the pores of anodic alumina (AAO) templates. The processing of stoichiometric nanowires of La_0.67Sr_0.33MnO₃ (LSMO) at relatively low temperatures (870 K) is greatly aided by the linear chain polymer cation complex formed by ethylene glycol. The nanowires were found to grow preferentially along the <110> direction of cubic LSMO. The growth of oriented nanowires was achieved by: (a) electrostatically confining the sol particles to the core regions of the cylindrical pores of the template- this avoids heterogeneous nucleation of LSMO on amorphous pore walls and (b) introducing a polymer matrix that serves as a backbone structure to the growing crystallites- this facilitates reorientation of the grains during heat treatment. The nanowires are ferromagnetic at room temperature and exhibit a ferromagnetic transition temperature (T_c) of 370 K.