title: Enhanced spin Seebeck effect signal due to spin-momentum locked topological surface states.
abstract: Spin-momentum locking in protected surface states enables efficient electrical detection of magnon decay at a magnetic-insulator/topological-insulator heterojunction. Here we demonstrate this property using the spin Seebeck effect (SSE), that is, measuring the transverse thermoelectric response to a temperature gradient across a thin film of yttrium iron garnet, an insulating ferrimagnet, and forming a heterojunction with (BixSb1-x)2Te3, a topological insulator. The non-equilibrium magnon population established at the interface can decay in part by interactions of magnons with electrons near the Fermi energy of the topological insulator. When this decay channel is made active by tuning (BixSb1-x)2Te3 into a bulk insulator, a large electromotive force emerges in the direction perpendicular to the in-plane magnetization of yttrium iron garnet. The enhanced, tunable SSE which occurs when the Fermi level lies in the bulk gap offers unique advantages over the usual SSE in metals and therefore opens up exciting possibilities in spintronics.
authors.affiliation: Department of Physics and Astronomy, University of California, 3401 Watkins Drive, Riverside, California 92521, USA.
authors.forename: Zilong
authors.initials: Z
authors.lastname: Jiang
authors.affiliation: Francis Bitter Magnet Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Cui-Zu
authors.initials: CZ
authors.lastname: Chang
authors.affiliation: Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Massoud Ramezani
authors.initials: MR
authors.lastname: Masir
authors.affiliation: Department of Physics and Astronomy, University of California, 3401 Watkins Drive, Riverside, California 92521, USA.
authors.forename: Chi
authors.initials: C
authors.lastname: Tang
authors.affiliation: Department of Physics and Astronomy, University of California, 3401 Watkins Drive, Riverside, California 92521, USA.
authors.forename: Yadong
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Francis Bitter Magnet Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.|Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Jagadeesh S
authors.initials: JS
authors.lastname: Moodera
authors.affiliation: Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Allan H
authors.initials: AH
authors.lastname: MacDonald
authors.affiliation: Department of Physics and Astronomy, University of California, 3401 Watkins Drive, Riverside, California 92521, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Shi