Gigantic negative magnetoresistance in a disordered Topological Insulator
Oliver Breunig (University of Cologne)

Recently the phenomenon of negative magnetoresistance (MR) is attracting renewed interest due to its occurrence in Weyl semimetals because of the chiral anomaly. In other systems a large MR typically relates to magnetism. In this talk a novel mechanism leading to a large negative MR will be presented that is based not on magnetism, but on disorder. In the newly synthesized bulk- insulating topological insulator material T1BixSb1-xTe2 we find a suppression of the resistivity by up to 98 % in 14 T at low temperature. From transport data and numerical simulations, this gigantic negative MR is understood by a percolation of charge puddles formed in the disordered bulk.