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Femtosecond Time- and Angle-Resolved Photoelectron Spectroscopy on Novel Quantum Materials

English title Femtosecond Time- and Angle-Resolved Photoelectron Spectroscopy on Novel Quantum Materials
Applicant Leuenberger Dominik
Number 147271
Funding scheme Fellowships for prospective researchers
Research institution Geballe Laboratory for Advanced Materials Stanford University
Institution of higher education Institution abroad - IACH
Main discipline Condensed Matter Physics
Start/End 01.04.2013 - 31.03.2014
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All Disciplines (2)

Discipline
Condensed Matter Physics
Other disciplines of Physics

Keywords (8)

Topological Insulators; Time-and Angle-Resolved Photoelectron Spectroscopy; Charge Density Wave Systems; Novel Quantum Materials; Collective Excitations in Correlated Materials; Solid State Physics; Angle-Resolved Photoelectron Spectroscopy (ARPES); Femtosecond Laser Pulses

Lay Summary (German)

Lead
Topologische Isolatoren (TI) sind eine neue Klasse von Materialien mit speziellen elektronischen Eigenschaften. Es sind elektrische Isolatoren mit leitenden metallischen Zuständen an der Oberfläche. Diese Zustände werden durch Symmetrien der elektronischen bezüglich der räumlichen Struktur erzeugt und sind sehr stabil (topologisch geschützt, z.B. gegen Verunreinigungen). Relativistische Effekte sorgen dafür, dass Spin und Ausbreitungsrichtung dieser Elektronen fest aneinander gekoppelt sind.
Lay summary

Inhalt und Ziel des Forschungsprojekts

Uebergeordnetes Ziel dieses Projekts ist es, die Relaxationsprozesse von angeregten elektronischen Zuständen auf topologischen Oberflächen auf der sehr kurzen Femtosekunden Zeitskala mit Hilfe von zeit- und winkelaufgelöster Elektronenspektroskopie direkt zu messen. Ein geplanter Ansatz ist mit sehr dünnen Filmen zu arbeiten, um die Dissipation der Elektronen von der Oberfläche weg ins Material zu unterdrücken. Dies sollte sehr lange Lebensdauern der angeregten topologischen Elektronenzustände erlauben. Ein weiterer Ansatz besteht darin, mit gezieltem Ladungs-Doping diese Relaxationsprozesse zu manipulieren.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

(i) Diese Arbeit ist fürs fundamentale physikalische Verständnis von elektronischen Streuprozessen untereinander und mit anderen Quasiteilchen in TI von Bedeutung. (ii) Die Experimente sollen das Design von neuen Bauelementen für Anwendungen im Bereich von Quantencomputern ermöglichen. (iii) Die untersuchten TI sind sehr geeignete thermoelektrische Materialien, die in nanostrukturierter Form höchst effizient thermische in elektrische Energie umformen können und somit für diverse energietechnische Anwendungen von grossem Interesse sind.


Direct link to Lay Summary Last update: 07.02.2013

Responsible applicant and co-applicants

Publications

Publication
Discovery of a Single Topological Dirac Fermion in a Strong Inversion Asymmetric Compound BiTeCl
Y. L. Chen M. Kanou Z. K. Liu H. J. Zhang J. A. Sobota D. Leuenberger S. K. Mo B. Zhou, S-L. Yang P. S. Kirchmann D. H. Lu R. G. Moore Z. Hussain Z. X. Shen X. L. Qi T. Sasagawa (2013), Discovery of a Single Topological Dirac Fermion in a Strong Inversion Asymmetric Compound BiTeCl, in Nature Physics, 9, 704-708.
Ultrafast electron dynamics in the topological insulator Bi2Se3 studied by time-resolved photoemission spectroscopy
J. A. Sobota S.-L. Yang D. Leuenberger A. F. Kemper J. G. Analytis I. R. Fisher, P. S. Kirchmann T. P. Devereaux and Z.-X. Shen, Ultrafast electron dynamics in the topological insulator Bi2Se3 studied by time-resolved photoemission spectroscopy, in Journal of Electron Spectroscopy and Related Phenomena.

Collaboration

Group / person Country
Types of collaboration
Department of Complex Matter Institut "Jozef Stefan", Ljubljana Slovenia (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Geballe Laboratory for Advanced Materials, Institute for Applied Physics, Stanford University United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Berkeley Lab Computing Sciences, Lawrence Berkeley National Laboratory United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Jahres Retreat der Stanford Optical Society (SOS) Poster Surgical Variation of Ultrafast Pump Photon Energy for Applications in Time-Resolved Photoelectron Spectroscopy and Time-resolved X-ray Diffraction 04.04.2014 Marconi Conference Center, Marshall, Kalifornien, United States of America Leuenberger Dominik;
Gordon Research Conference on Ultrafast Phenomena in Cooperative Systems Poster Near gap excitation of the Amplitude Mode in CeTe3 02.02.2014 Ventura, Kalifornien, United States of America Leuenberger Dominik;


Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
Bay Area Science Festival 24.10.2013 San Francisco, Kalifornien, United States of America Leuenberger Dominik;


Associated projects

Number Title Start Funding scheme
151328 Femtosecond Time- and Angle-Resolved Photoelectron Spectroscopy on Novel Quantum Materials 01.04.2014 Advanced Postdoc.Mobility

Abstract

The search for materials with novel electronic properties is an important topic within Condensed Matter Physics. The novel quantum material class of topological insulators reveal the existence of metallic surface states at the boundary of the insulating crystal. Due to strong spin-orbit interaction, the spin and momentum of the electrons in these states are intimately coupled, what provides channels to drive spin-polarized currents at the solid surface. Understanding how excited electrons in these spin-textured surface states scatter with electrons and other quasi-particles is crucial for the design of future spintronic devices. Femtosecond time- and angle-resolved photoelectron spectroscopy (trARPES) is currently developing rapidly and offers the opportunity to investigate these electron-electron scattering processes in topological insulators directly in the time-domain. In another class of materials, the strongly correlated Charge Density Wave (CDW) systems, strong electron-phonon coupling connects periodic lattice distortions with an electronic metal-to-insulator phase transition. Despite the fact, that trARPES allows for the ultrafast excitation and subsequent monitoring of collective modes close to that phase transition, still little is known about the mutual coupling strength of the distinct modes in these CDW materials.The project proposed here aims to investigate the non-equilibrium electronic structure and corresponding scattering processes on thin and (magnetically) doped films of the topological insulator Bi2Se3 and on RTe3 CDW systems by means of trARPES experiments. This is expected to bring new insight into the scattering rates of persistent non-equilibrium electronic populations in topological insulators as well as into the mutual coupling strength between distinct collective excitations in CDW systems, respectively. The experiments will be performed in Prof. Z.-X. Shen’s group at the Geballe Laboratory for Advanced Materials at Stanford University, offering a combination between photoemission experiment, material growth and theory.
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