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Soft X-Ray ARPES: From Bulk Materials to Buried Heterostructures and Impurities

Date
Feb 27, 2020
Time
2:00 PM - 3:30 PM
Speaker
Dr. Vladimir N. Strocov
Affiliation
Paul Scherrer Institute, PSI Villigen, Switzerland
Language
en
Main Topic
Materialien
Other Topics
Materialien
Host
Prof. Dr. Claudia Felser
Description
Soft X-Ray ARPES: From Bulk Materials to Buried Heterostructures and Impurities
Vladimir N. Strocov
Swiss Light Source, Paul Scherrer Institute, Villigen-PSI, Switzerland (vladimir.strocov@psi.ch)
ABSTRACT
Soft-X-ray ARPES (SX-ARPES) in the energy range around 1 keV benefits from enhanced photoelectron escape depth, sharp definition of 3D electron momentum k, and resonant photoexcitation delivering chemical specificity. These spectroscopic advantages allow SX-ARPES to push k-resolved electronic-structure investigations from bulk materials to buried heterostructures and impurity systems [1].
Bulk materials. – Applications of SX-ARPES to bulk materials are based on sharp definition of the out-of-plane momentum resulting from the enhanced photoelectron delocalization. Examples include 3D-nested Fermi surface of VSe2 forming exotic charge-density waves [2], 3D effects in complex oxides connected with their polaronic activity, 3D band dispersions in topological materials, etc.
Buried heterostructures. – Semiconductor systems are illustrated by AlGaN/GaN high-electron-mobility heterostructures, where SX-ARPES resolves anisotropic Fermi surface (Figure) and band dispersions of the interfacial quantum-well states [3]. A "drosophila" oxide interface is LaAlO3/SrTiO3. Resonant photoexcitation at the Ti L-edge resolves here interfacial subbands, whose peak-dip-hump spectral function identifies a multiphonon polaronic nature of the charge carriers [4]. Further cases include EuO/Si spin injectors, EuS/ Bi3Se2 topological interfaces, etc.
Impurity systems. – Ga(Mn)As is a paradigm diluted magnetic semiconductor. Resonant photo-excitation at the Mn L-edge identifies energy alignment and hybridization of the Mn impurities with host GaAs, disclosing the mechanism of ferromagnetic electron transport [5]. Other cases include magnetic V impurities in topological Bi3Se2 competing with the quantum anomalous Hall effect [6], etc.
This review on the spectroscopic potential of SX-ARPES is concluded by introducing a multichannel spin detector iMott whose four-order efficiency increase will propel spin-texture analysis from bulk materials to buried heterostructures and impurities.
REFERENCES
1. V.N. Strocov et al., J. Synchr. Rad. 236 (2019) 1
2. V.N. Strocov et al., Phys. Rev. Lett. 109 (2012) 086401
3. L.L. Lev et al., Nature Comm. 9 (2018) 2653
4. C. Cancellieri et al., Nature Comm. 7 (2016) 10386
5. M. Kobayashi et al., Phys. Rev. B 89 (2014) 205204
6. J. Krieger et al., Phys. Rev. B 96 (2017) 184402
Links

Last modified: Feb 28, 2020, 12:08:45 AM

Location

Max-Planck-Institut für Chemische Physik fester Stoffe (Seminarraum 1+2, Nöthnitzer Straße 40, 01187 Dresden)Nöthnitzer Straße4001187Dresden
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MPI-CPfS
Homepage
http://www.cpfs.mpg.de/

Organizer

Max-Planck-Institut für Chemische Physik fester StoffeNöthnitzer Straße4001187Dresden
E-Mail
MPI-CPfS
Homepage
http://www.cpfs.mpg.de/
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