Coherent ultrafast spin-dynamics probed in three dimensional topological insulators.
Topological insulators are candidates to open up a novel route in spin based electronics. Different to traditional ferromagnetic materials, where the carrier spin-polarization and magnetization are based on the exchange interaction, the spin properties in topological insulators are based on the coupling of spin- and orbit interaction connected to its momentum. Specific ways to control the spin-polarization with light have been demonstrated: the energy momentum landscape of the Dirac cone provides spin-momentum locking of the charge current and its spin. We investigate a spin-related signal present only during the laser excitation studying real and imaginary part of the complex Kerr angle by disentangling spin and lattice contributions. This coherent signal is only present at the time of the pump-pulses' light field and can be described in terms of a Raman coherence time. The Raman transition involves states at the bottom edge of the conduction band. We demonstrate a coherent femtosecond control of spin-polarization for electronic states at around the Dirac cone.
Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.|Dipartimento di Fisica, Politecnico di Milano, 20133 Milan, Italy.
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F
Boschini
Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
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M
Mansurova
Peter Grünberg Institut (PGI-9) and Jülich-Aachen Research Alliance (JARA-FIT), Forschungszentrum Jülich, 52425 Jülich, Germany.
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Mussler
Peter Grünberg Institut (PGI-9) and Jülich-Aachen Research Alliance (JARA-FIT), Forschungszentrum Jülich, 52425 Jülich, Germany.
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J
Kampmeier
Peter Grünberg Institut (PGI-9) and Jülich-Aachen Research Alliance (JARA-FIT), Forschungszentrum Jülich, 52425 Jülich, Germany.
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Grützmacher
Department of Physical Chemistry, Fritz Haber Institute, Faradayweg 4-6, 14195 Berlin, Germany.
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Braun
Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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Katmis
Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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JS
Moodera
IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, 20133 Milan, Italy.
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Dallera
Dipartimento di Fisica, Politecnico di Milano, 20133 Milan, Italy.
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Carpene
Physikalisches Institut, Justus-Liebig-Universität Gießen, 35392 Gießen, Germany.
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Franz
Physikalisches Institut, Justus-Liebig-Universität Gießen, 35392 Gießen, Germany.
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Czerner
Physikalisches Institut, Justus-Liebig-Universität Gießen, 35392 Gießen, Germany.
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C
Heiliger
Department of Physical Chemistry, Fritz Haber Institute, Faradayweg 4-6, 14195 Berlin, Germany.
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T
Kampfrath
Institut für Physik, Ernst-Moritz-Arndt Universität Greifswald, Felix-Hausdorff-Straße 6, 17489 Greifswald, Germany.
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Münzenberg