A high-temperature ferromagnetic topological insulating phase by proximity coupling.

Autor: Katmis F; Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.; Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.; Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA., Lauter V; Quantum Condensed Matter Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA., Nogueira FS; Institut fuer Theoretische Physik III, Ruhr-Universitaet Bochum, D-44801 Bochum, Germany.; Institute for Theoretical Solid State Physics, Institut fuer Festkoerper- und Werkstoffforschung, Dresden, D-01069 Dresden, Germany., Assaf BA; Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA.; Département de Physique, Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Paris Sciences et Lettres Research University, Paris 75005, France., Jamer ME; Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA., Wei P; Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.; Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.; Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA., Satpati B; Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 64, India., Freeland JW; Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA., Eremin I; Institut fuer Theoretische Physik III, Ruhr-Universitaet Bochum, D-44801 Bochum, Germany., Heiman D; Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA., Jarillo-Herrero P; Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA., Moodera JS; Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.; Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.; Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Jazyk: angličtina
Zdroj: Nature [Nature] 2016 May 26; Vol. 533 (7604), pp. 513-6. Date of Electronic Publication: 2016 May 09.
DOI: 10.1038/nature17635
Abstrakt: Topological insulators are insulating materials that display conducting surface states protected by time-reversal symmetry, wherein electron spins are locked to their momentum. This unique property opens up new opportunities for creating next-generation electronic, spintronic and quantum computation devices. Introducing ferromagnetic order into a topological insulator system without compromising its distinctive quantum coherent features could lead to the realization of several predicted physical phenomena. In particular, achieving robust long-range magnetic order at the surface of the topological insulator at specific locations without introducing spin-scattering centres could open up new possibilities for devices. Here we use spin-polarized neutron reflectivity experiments to demonstrate topologically enhanced interface magnetism by coupling a ferromagnetic insulator (EuS) to a topological insulator (Bi2Se3) in a bilayer system. This interfacial ferromagnetism persists up to room temperature, even though the ferromagnetic insulator is known to order ferromagnetically only at low temperatures (<17 K). The magnetism induced at the interface resulting from the large spin-orbit interaction and the spin-momentum locking of the topological insulator surface greatly enhances the magnetic ordering (Curie) temperature of this bilayer system. The ferromagnetism extends ~2 nm into the Bi2Se3 from the interface. Owing to the short-range nature of the ferromagnetic exchange interaction, the time-reversal symmetry is broken only near the surface of a topological insulator, while leaving its bulk states unaffected. The topological magneto-electric response originating in such an engineered topological insulator could allow efficient manipulation of the magnetization dynamics by an electric field, providing an energy-efficient topological control mechanism for future spin-based technologies.
Databáze: MEDLINE
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