title: Memory effect in a topological surface state of Bi2Te2Se.
abstract: We demonstrate the controllable local manipulation of the Dirac surface state in a topological insulator, Bi2Te2Se, which has suppressed bulk carrier density. Using scanning tunneling microscopy/spectroscopy under magnetic fields, we observe Landau levels of the Dirac surface state in the conductance spectra. The Landau levels start to shift in their energy once the bias voltage between the tip and the sample exceeds a threshold value. The amount of shift depends on the history of bias ramping. As a result, conductance spectra show noticeable hysteresis, giving rise to a memory effect. The conductance images exhibit spatially inhomogeneous patterns which can also be controlled by the bias voltage in a reproducible way. On the basis of these observations, we argue that the memory effect is associated with the tip-induced local charging effect which is pinned by the defect-generated random potential. Our study opens up a new avenue to controlling the topological surface state.
authors.affiliation: RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan. yfu@riken.jp
authors.forename: Ying-Shuang
authors.initials: YS
authors.lastname: Fu
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Hanaguri
authors.forename: Shuhei
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Kyushiro
authors.initials: K
authors.lastname: Igarashi
authors.forename: Hidenori
authors.initials: H
authors.lastname: Takagi
authors.forename: Takao
authors.initials: T
authors.lastname: Sasagawa