Synthesis and Magnetic Properties of Mn4Si7 and Si–Mn4Si7 Axial Heterostructure Nanowire Arrays

Manganese silicides nanostructures showed great potential applications in microelectronic and optoelectronic devices. In this study, Mn4Si7 and Si–Mn4Si7 axial heterostructure nanowire arrays were synthesized by the in-situ reaction between Si nanowire arrays and MnCl2. Depending on the reaction durations and processes, structures (Mn4Si7 nanowires or Si–Mn4Si7 axial heterostructure nanowires) and lengths of the Mn4Si7 nanowires could be readily tuned. Phase identification were performed by the XRD, TEM, HRTEM, and SAED means, which results indicated that the as-synthesized nanowire is Nowotny chimney ladder (NCL) structure Mn4Si7 with a tetragonal structure. The Mn4Si7 nanowire arrays exhibited enhanced ferromagnetism comparing with other bulk higher manganese silicides. The Curie temperature of the Mn4Si7 nanowire arrays is over 300 K, which is much higher than that of the previous reports. Because of the good compatibility with Si-based nanowire devices and many favorable properties, these Mn4Si7 nanow...