Conductive and Non-conductive Dislocations in Bi-Sb Topological Insulators

Electrical resistivity measurements were performed for plastically deformed Bi Sb topological insulators to investigate the formation of one-dimensional gapless states along dislocations, which has been previously discussed theoretically. Micrometer-sized samples were used for the measurements, so as to investigate the correlation between local dislocation density and electrical resistivity. Two types of samples with different deformation orientations were prepared; the dislocations introduced in one type satisfy the theoretical condition for the formation of gapless conductive states while those in the other do not. The former type of samples exhibited much reduced resistivity in a low temperature region below 50 K, compared with the latter or undeformed samples, which can be attributed to one-dimensional conduction along dislocations.