Growth Mechanism of SmB6 Nanowires Synthesized by Chemical Vapor Deposition: Catalyst-Assisted and Catalyst-Free

SmB6nanowires, as a prototype of nanostructured topological Kondo insulator, have shown rich novel physical phenomena relating to their surface. Catalyst-assisted chemical vapor deposition (CVD) is a common approach to prepare SmB6nanowires and Ni is the most popular catalyst used to initiate the growth of SmB6nanowires. Here, we study the effect of growth mechanism on the surface of SmB6nanowires synthesized by CVD. Two types of SmB6nanowires are obtained when using Ni as the catalyst. In addition to pure SmB6nanowires without Ni impurity, a small amount of Ni is detected on the surface of some SmB6nanowires by element analysis with transmission electron microscopy. In order to eliminate the possible distribution of Ni on nanowire surface, we synthesize single crystalline SmB6nanowires by CVD without using catalyst. The difference between catalyst-assisted and catalyst-free growth mechanism is discussed.Keywords:nanowires;synthesis;CVD;topological insulators;growth mechanism