title: Persistent optical gating of a topological insulator.
abstract: The spin-polarized surface states of topological insulators (TIs) are attractive for applications in spintronics and quantum computing. A central challenge with these materials is to reliably tune the chemical potential of their electrons with respect to the Dirac point and the bulk bands. We demonstrate persistent, bidirectional optical control of the chemical potential of (Bi,Sb)2Te3 thin films grown on SrTiO3. By optically modulating a space-charge layer in the SrTiO3 substrates, we induce a persistent field effect in the TI films comparable to electrostatic gating techniques but without additional materials or processing. This enables us to optically pattern arbitrarily shaped p- and n-type regions in a TI, which we subsequently image with scanning photocurrent microscopy. The ability to optically write and erase mesoscopic electronic structures in a TI may aid in the investigation of the unique properties of the topological insulating phase. The gating effect also generalizes to other thin-film materials, suggesting that these phenomena could provide optical control of chemical potential in a wide range of ultrathin electronic systems.
authors.affiliation: Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA. ; Department of Physics, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Yeats
authors.affiliation: Department of Physics, Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Pan
authors.affiliation: Department of Physics, Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Richardella
authors.affiliation: Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Mintun
authors.affiliation: Department of Physics, Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Nitin
authors.initials: N
authors.lastname: Samarth
authors.affiliation: Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA. ; Department of Physics, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
authors.forename: David D
authors.initials: DD
authors.lastname: Awschalom
keywords: (Bi,Sb)2Te3; Chemical potential tuning; Hall effect; Photocurrent microscopy; SrTiO3; complex oxides; magnetoresistance; optical patterning; topological insulators; weak antilocalization