Single crystalline β-Ag ₂Te nanowire as a new topological insulator

A recent theoretical study suggested that Ag ₂Te is a topological insulator with a highly anisotropic Dirac cone. Novel physics in the topological insulators with an anisotropic Dirac cone is anticipated due to the violation of rotational invariance. From magnetoresistance (MR) measurements of Ag ₂Te nanowires (NWs), we have observed Aharanov-Bohm (AB) oscillation, which is attributed to the quantum interference of electron phase around the perimeter of the NW. Angle and temperature dependences of the AB oscillation indicate the existence of conducting surface states in the NWs, confirming that Ag ₂Te is a topological insulator. For Ag ₂Te nanoplates (NPLs), we have observed high carrier mobility exceeding 22 000 cm ²/(V s) and pronounced Shubnikov-de Haas (SdH) oscillation. From the SdH oscillation, we have obtained Fermi state parameters of the Ag ₂Te NPLs, which can provide valuable information on Ag ₂Te. Understanding the basic physics of the topological insulator with an anisotropic Dirac cone could lead to new applications in nanoelectronics and spintronics.