Low-energy μSR Study on the Tetradymite Topological Insulator Bi1.5Sb0.5TeSe2

A new method utilizing the low energy muon spin rotation (μSR) technique to investigate the spin structure within the surface layer of topological insulator has been proposed. In order to detect the spin polarization parallel with the surface, one applies a weak field Bpar, which, by breaking the time reversal symmetry, is expected to induce a net magnetization perpendicular the surface. This will affect the profile of muon spin depolarization spectra. Preliminary measurements on the topological insulator Bi1.5Sb0.5TeSe2 with tetradymite structure are also shown.