非表示:
キーワード:
-
要旨:
Topological insulators are known for their metallic surface states, a
result of strong spin-orbit coupling, that exhibit unique surface
transport phenomenon. However, these surface transport phenomena are
buried in the presence of metallic bulk conduction. We synthesized very
high quality Bi2Te2Se single crystals by using a modified Bridgman
method that possess high bulk resistivity of >20 Omega cm below 20 K,
whereas the bulk is mostly inactive and surface transport dominates. The
temperature dependence of resistivity follows an activation law like a
gap semiconductor in temperature range 20-300 K. To extract the surface
transport from that of the bulk, we designed a special measurement
geometry to measure the resistance and found that single-crystal
Bi2Te2Se exhibits a crossover from bulk to surface conduction at 20 K.
Simultaneously, the material also shows strong evidence of weak
antilocalization in magnetotransport owing to the protection against
scattering by conducting surface states. This simple geometry
facilitates finding evidence of surface transport in topological
insulators, which are promising materials for future spintronic
applications.
